or How to avoid going insane trying to get the same route on your phone and your GPS.

1. Preface
There is a method that can keep the routing madness under control when trying to cause common GPS routing solution generation with REVER, Garmin GPS and Goldwing (2019+), or for that matter, any other GPS routing platform. Without observing some very specific procedures and settings in each platform, a common GPX waypoint listing can produce wildly different routes, leading to enormous confusion in a group ride where different riders are using different GPS systems.

The language chosen in the preceding paragraph speaks to the central principle that must be recognized in any effort to produce common routing results across multiple platforms, to wit, each GPS platform makes its own decisions about how to convert a list of waypoints (imported from another platform via a GPX file). Moreover, most platforms offer a set of routing decision biases (or Routing Options) that the user can select to influence how that platform produces a route (e.g., users may choose “Fastest Route” or “Curvy Roads” or “Avoid Highways”) And, of course, each platform makes its own decisions about how to implement a routing bias, even if one or more other platforms use exactly the same terminology to name the route bias (i.e. “Avoid Highways” on one platform is not guaranteed to have the same effect on a different platform). So…

The objective being addressed here is being able to generate a route in one platform and then export it to other platforms and get the same route on each of them.

The fundamental methodology is to create a route in one platform, export it to a different platform, compare the results, and IF THEY DO NOT AGREE, add waypoints to the route IN THE ORIGINAL PLATFORM and re-export the route to the target platform, to see if route agreement has been achieved. Eventually the original platform route will have enough waypoints in it to force the target platforms to produce a matching route. (Yes, this means the original platform has a bunch of waypoints in it that are superfluous on the original platform…but that is ok. They do not hurt the originating platform routing performance.

As a practical matter, it is important to set each platform to a routing mode that approximates that used on the originating platform. A lot of frustration will erupt if the originating platform prefers “fastest route” and disallows unpaved roads…but the target platform is set to generate the shortest route and allows dirt roads.
It must also be noted that the map databases that each platform use for route generation may disagree about map facts. (e.g., one may identify a road as unpaved, when satellite or “street view” in another platform makes it clear the road in question is, in-fact, paved). These sorts of disconnects are very difficult to overcome and may force you to simply abandon plans for that road and take another one (if you want the various platforms to agree on the route).  
 
The “Why So Many GPS Platforms?” Sidebar
I can tell you why I use more that one platform. The #1 reason I always travel with a “REAL” GPS unit, despite how much I LOVE cloud-based navigation solutions like Google Maps or REVER, is that even though those platforms support downloading map data so that your cell phone continues to provide routing instructions even when you ride into a massive dead zone, if you are in a dead zone and need to generate a new route (e.g., your riding buddy has had a wreck and you need to get to a hospital), the cloud-based smartphone navigation tools simply cannot do any route generations tasks without a network connection. Route generation is always handled by the server at the other end of the network connection. Yes, it is true, there are some smartphone/tablet navigation apps, such as Sygic (which works well in the USA, despite its decidedly European bias), that actually do local (using the phone’s processor and memory) route generation…and therefore are a suitable substitute for a “Real” GPS unit. But being a belt & suspenders kind of guy, I prefer my back-up navigation solution to be in a physically separate device so it will still work if the cell phone stops working, whether the cause is a bad cell connection or a dead battery (or I dropped it).
 
So, having said all that, what follows is methodology I have developed and, for the most part, like using.
 
2. The Tools
I depend on Google Maps, Garmin Zumo and lately REVER (https://a.rever.co/). I have been a heavy user of GPS navigation since the first handheld moving map GPS was released for sale by Garmin (I still have mine.). And I can say with complete enthusiasm, REVER is, by far, the easiest motorcycle route planning tool I have ever seen, despite a little wonky weirdness in the user interface. I love it and use it to plan new ride routes at home on my computer, despite the fact the cell phone version goes stupid without a live network connection. And it must be said, the cell phone version, intended to be used while you ride, does have some pretty cool features...more if you get the paid version, notably, live weather overlays on your live route map. Despite that, the Garmin Zumo is by far the best on-bike active navigation system to use while on a ride, especially to places with spotty cell phone coverage (indeed, usually my favorite places). But route planning on the Zumo is practically impossible...and doing it on the Garmin PC program, BaseCamp, is just plain painful…doable, but painful. Route planning on the Goldwing Navigation System is both difficult and dumb. (Who wants to sit in the garage for hours thumbing the control buttons like it was a flip phone?!) And using the Goldwing Navigation System on the road is the worst. Nanny Attitude has rendered it unusable for anything but long hauls down hundreds of miles of straight interstate highways. A rider cannot even change the zoom view of the display while in motion! Pass.

Therefore, my methodology is to generate routes in REVER and then export them (via GPX files) to other platforms, notably the Garmin Zumo, and the Honda Goldwing Navigation System (for my friends who only have the Goldwing system to back up Rever on their phones when they are on a ride).  

My previous first love was Google Maps, and I still use Google Maps more than any other platform on a daily basis. But Google Maps has a fatal flaw (besides going dumb without a network connection). It will not export or import a GPX waypoint listing. In the past I would develop a route in Google Maps (using the Topo map, Street View, Satellite View, and various routing options) to generate routes I could believe in, and then re-create those routes by hand in Garmin BaseCamp so I could load them into my Garmin Zumo or export them to other platforms via the BaseCamp GPX export feature (which often proved unsuccessful).

So, here’s the inside scoop (not fact checked, but I believe this is true based on my own observations) … REVER is pretty obviously based on Google Maps. Both platforms seem to be working from the same data base and implementing virtually identical routing algorithms (which is just me being tentative…they really look identical to me).

The downbeat on this is that the OEM Goldwing (+2019) Navigation system ALSO seems to have Google Maps DNA. It is useful to note that the Honda Route Planning tool (now discontinued) was absolutely shamelessly built on Google Maps…suggesting, at least to me, that the INDEPENDENT routing algorithms that have been implemented in the Goldwing navigation system have been intentionally designed to mimic the decisions being made by the Google Maps servers when they build a route.

So…given that my personal objective has been to generate routes in one platform and then have them successfully reproduced, turn-for-turn, by my cell phone (formerly running Google Maps but now running the REVER app), my Garmin Zumo, and a Goldwing Nav System, REVER has emerged as the right choice for initial route planning and the obvious source for GPX data to be used by both BaseCamp (on the way to the Zumo) and the Goldwing Nav System. It works pretty darn well, IF you have your settings right on each platform AND you follow the baseline procedure (which is: If you see an error / route discrepancy, FIX IT IN THE SOURCE ROUTE. Yes, it seems like a time-consuming PIA…but it eliminates a ton of chasing your own tail later. Do yourself a favor. Make the commitment to use the methodology

A Word to the Wise: I have seen, on multiple occasions, GPX routes, exported from Garmin BaseCamp, are scrambled. Waypoints are re-ordered such that when they are put into a different platform, the resulting route makes no sense at all. I do not pretend to know why this happens, but it does. Bottom line: Do not expect an exported Garmin route to work.
 
3. Platform Settings
First, a word on the backbone of the methodology recommended here. The key to making matching routes across multiple platforms is to put enough waypoints into the initial route planning tool for the exported GPX file to have so many waypoints that the receiving device effectively has no choice but to generate a matching route (almost regardless of the receiving platform’s route planning option settings). As a practical matter, that is not actually achievable, because radically wrong settings on the receiving platform will screw things up. Still, at the highest-level view of all this, route planning option choices are secondary…very important, but secondary, to setting enough waypoints.

Note: This is the significant way in which using Google Maps for route planning can be counter-productive, and would be, even if it would allow export of a GPX file. Google Maps allows TOO FEW waypoints to be added to a single route. So few waypoints are allowed, a user must string multiple Google Maps routes together to get an adequate waypoint list. (I am talking to you Google…this is a dumb restriction.)

Therefore, while I may use some of the gross routing option choices, like Avoid Highways, in the early stages of looking at a potential route, when it comes to building the route file I actually plan to use, I generally ONLY select Avoid Unpaved Roads. In REVER, this is a first-level configuration choice when you start your route planning. Find it and use it if you are a road rider. Adventure riders may want to make a different choice.

Pro Tip: Different map databases disagree on which roads are paved and which ones are dirt. If your routes in the boonies will not converge over multiple platforms, check that first as it is likely to be the problem.

To be absolutely clear, the way I get the initial route on Rever that I want is to put in enough waypoints to get me where I want to go (usually avoiding Interstates, freeways, tollways, steel-mesh roadway bridges, ferry crossings, and rattlesnake dens).

REVER
The Rever planning tool first lets you pick what type of riding you want to do (on-road or off-road) and then offers three routing bias rules: Avoid Tolls, Avoid Hwy, Avoid Ferry. I choose Avoid Tolls. Whether you elect to Avoid Tolls or anything else, it is likely to be best if you use a similar setting on other platforms.

GARMIN ZUMO
Garmin is a little more complicated. Before the Rever GPX output file can be put into Zumo, it needs to pass through BaseCamp. BaseCamp will turn the GPX file into a native Garmin Zumo file that can be loaded into the Zumo. BaseCamp allows you to (actually, requires you to) set a suite of baseline routing preferences for each class of activity you may choose to associate with the route in question. Obviously, the route you would get If you set the route class to Hike (on foot) vs. Automobile, the route produced will be wildly different. And there are subgroups of activities such as Fastest Motorcycling or Shortest Automobile trip. The point is, the route comes into BaseCamp undifferentiated (from Garmin’s point of view), so once in BaseCamp, the route must be opened and assigned an activity class by the user. BaseCamp does not generate a road route until the class is set. Normally, one would set the route to Motorcycling. Automotive is also a workable setting. And, my nominal routing preference for the Motorcycling activity when touring with Garmin is Fastest Route.

GOLDWING (+2019)
Note: The “+2019” denotes the latest generation Goldwing (the Goldwing Tour and derivatives) which has different GPS than earlier Goldwing models. It is better, but it still sucks. 

The Goldwing GPS also offers just a few route bias options. Believe me, you don’t want to be in the dirt with a Goldwing. Other than that, choose lightly.
 
4. The Procedure
Now that you have these pages of background information in mind, the actual procedure is very simple.

1. Build a route in Rever.
2. Export the Rever route*.
3. Import the exported GPX file.
4. Compare the route produced by the target platform to the Rever route.

• If it matches – Stop. Have a beer.
• If it does not match

            A. Note the discontinuity.
         B. Go back to Rever and add a waypoint in a strategic spot on the Rever route and then go back to Step 2.

In Rever, put the new waypoint directly on the existing Rever route in the spot some distance past where the target platform diverged from the Rever route. This is to force the target platform to pull the route to the desired route. The key is to pick a spot that is far enough down the Rever route for the target platform to plot the route to THAT spot AND continue along the Rever route, rather than double back and try to return to the divergent route plotted by the target system. Sometimes multiple additional waypoints are required to prevent the target system from misbehaving.

*Note: I always choose the “Export to Goldwing +2019” option…ESPECIALLY if I am going to export the route to my Garmin Zumo! Yes, I know there are some Export to Garmin options. I was not happy with the outcome.

5. But What About Google Maps?!
I love Google Maps and use it on a daily basis; more than any other phone app. I use it for ordinary local route driving, whether running errands, or for current traffic conditions while commuting, or to just find phone numbers and/or reviews of local businesses. But the fact remains, it just stinks for cooperating with other platforms. If you have a multi-platform task at hand, I say avoid Google Maps at all cost. If you insist on trying to replicate a route on Google Maps, the fastest, least painful way to do it is by hand, typing in waypoint by waypoint the duplicate route you want to create. Yuck. The better choice is to get a free copy of REVER. (BTW, I get no compensation from REVER or anyone connected with them for these comments.)

Customers often ask, "What tools should I buy?"  Naturally, the only credible answer is "It depends...". Despite that, I want to take a stab at an answer. Here's the broad list for someone wanting to work on their own motorcycle, but it is not a bad start for other mechanical work. I have built this list on my sense of what I use most often. The less often I pick it up, the lower on the list it goes.

Note: Some readers may look at this list and have no idea what the difference is between a combination wrench and a set of slip-joint pliers. For that, I apologize. It is a little beyond the scope of this article. Here's my suggestion: Read tool catalogs. Go to stores that sell tools. Pick them up and read the labels. Dig into a friend's tool box and ask "What's this thing?" Hey, it's what I did. I still do. Nothing is more fun than hitting the tool isle, picking up something unfamiliar, and saying "What the heck is that?!" And education almost always follows. 

Believe it or not, #1 on my list is always an air compressor, inflator gauge/air chuck and blow gun. If you cannot do anything else to maintain your machines, at least be able to keep the tires set to spec pressure. The blow gun costs almost nothing and allows you to clean and dry nasty mechanical doodads to your heart's content. A small unit (120 volt, 1 horsepower motor, 2 gallon tank, able to supply at least 2 cfm @ 90 psi) is large enough for most daily needs. That last figure, cfm or cubic feet per minute, refers to the flow rate the unit can manage...i.e. how much air it can pump. A max PSI rating is almost meaningless...and the one that is always shown first on the box. Don't be fooled by a compressor that tries to sell you on a high max psi spec. You never need more than 100 psi in the shop. Flow rate is the true measure of compressor capacity...and flow rate at a specific pressure is the way to compare. 3 cfm @ 40 psi is not better than 2 cfm @ 90 psi. If you plan to buy a air-driven impact gun like they use in tire shops, a compressor twice to three times that size is needed, but battery powered impact guns are making that sort of tool much less popular, so don't sweat it. 

But...lots of folks start with hand tools before they ever get a compressor. Walk your own path.

As for hand tools, after many years of experience, it is my opinion it is better in the long run to buy multiple large sets of single types of tools, than you are buying "starter tool sets" that have a few examples of many types of tools (that you must add to later piecemeal). For example, a set of metric combination wrenches (wrenches that have an open jaw on one end and a box-end of the same size on the other) that covers from 6mm to 32mm may have 22 or more wrenches in the set. A starter mechanic's tool kit may have six or eight. A starter set will have a mix of SAE (inch-based) and metric wrenches. If you have a bike from Asia or Europe, it will not have any SAE fasteners on it, so half the set you bought is useless (assuming you don't have other American-made stuff to fix, like I do). BUT, if you are going to buy a "mechanic's tool set", get the biggest one you can afford. It will cost you less in the long run.

And perhaps this goes without saying, but I will say it anyway, buy name brands with lifetime warranties. A no-name brand with a lifetime warranty is no warranty at all. If you cannot find them in 20 years, you are on your own. I recommend JIS Screwdrivers by Vessel. For wrenches, pliers, hex keys, etc. go with Craftsman, GearWrench, Crescent, Kobalt, Husky, and others.  For magnetic bowls, picks & probes, punches & chisels, hammers, flashlights, oil pans & funnels, brake bleeders, oil evacuators and and all that sort of miscellaneous stuff, Harbor Freight is a great resource. (I have some Harbor Freight wrenches. Not thrilled.)

So, here's my basic hand tool list, in priority order (yellow items are really high priority).

You can't solve a problem you can't see... 

• High intensity flashlight
• Broad beam work light

These tools let you tighten and loosen screws of various sorts.

• JIS Screwdriver Set (JIS = Japanese Industrial Standard... Never use an American "Philips" screwdriver on your metric bike. It will strip the screw heads. Every. Damn. Time.)  If you don't already have some, get a set that includes flat blade screwdrivers too, just for good measure.
• Long Hex Key Set (a.k.a. Allen Wrenches) and/or Hex Key Set for a socket wrench
• Long Torx Set (sometimes called star-drive) and/or Torx Driver Set for a socket wrench

There are a billion different types of pliers that let you grab things that your fingers cannot reach or hold. A single set will generally (and should) include:

• Basic slip-joint pliers
• Needle nose pliers
• Curved Jaw Locking pliers (the original invention name: Vice-Grips)
• Large Curved Jaw slip-joint pliers (the original invention name: Channel Locks)
• Diagonal wire cutters

But buying a set of common pliers, a set of Vice-Grips (small to large), a set of slip-joint pliers (large to small...and I like some by Vice-Grip), and a set of wire management tools is a very credible way to go.

Handling nuts and bolts comes next.

• Metric Combination Wrench Set (6mm to 32mm prefered, 8mm to 19mm minimum)
• Socket Wrench Sets (in order of priority) and associated Torque wrench handle for each. Get both standard and deep sockets, You won't regret it.

1. 3/8" drive Socket Set (covering 10mm, 12mm, 14mm, 17mm, 19mm at least) & 3/8" drive torque wrench
2. 1/4" drive Socket Set (covering 8mm, 10mm, 12mm at least) & 1/4" drive  torque wrench
3. 1/2" drive Socket Set (covering 14mm, 17mm, 19mm and selected larger sizes for axle nuts) & 1/2" drive  torque wrench

A set of plain old combination wrenches and a middle sized socket set (highlighted in yellow above) cover lots of mechanical ground. Note that the 3/8" drive set covers most of the bases. The 1/4" set is better for fine work, and the 1/2" set is good for big stuff like wheel nuts and suspension work. You can go a while without the 1/2" set. Get a torque wrench for each set so you get things right on reassembly.

Tools to reduce cursing and general frustration...

• ​Magnetic parts bowls (Get a half dozen! So handy for keeping track of screws, nuts and bolts.)
• Magnetic & Claw Grabbers (You will drop a nut or bolt into the most impossible place to reach at least once during each job.)
• A Pick & Probe Set. (Kind of like the dentist uses. Very handy. Too cheap to not have them.)
• WD40 Spray (Let it soak into stuck threads for a few minutes and then try again. Also a great cleaner.)
• Brake Cleaner Spray (Clean off oil & grease so you can see what you are doing.)
• Starting Fluid Spray (The best diagnostic tool when an engine spins but won't start.)

And some specialized tools made for specific jobs...
For an oil change (even a transmission or final drive gear oil change)...

• Oil Filter Pliers / Wrench / Socket (depending on your bike)
• Oil Drain pan
• Oil funnel

For a brake fluid change...

• Pneumatic Brake Fluid Bleeding Kit PLUS In-line check valve

For electrical troubleshooting & repair...

• Multimeter (a Volt & Ohm meter)
• Wire strippers
• Wire crimpers
• Battery tender / Battery charger
• Jump battery

Some sort of jack, stands or a lift... The right type for you depends on your bike and the sort of work you need to do...and frankly, on how old you are. Speaking for myself, crawling around on the shop floor to work on a bike sucks. I am never going back to working without a lift. But it is clear that a $1500 motorcycle lift is not exactly a starter item. On the other hand, lots of service procedures require the bike to be vertical. If your bike has a built-in center stand and you don't plan to remove the front wheel, you are already all set... but not every bike has one. For many bikes a scissor jack for motorcycles is just the ticket. For others, like Sport bikes (that generally should not be jacked up from below the engine because the pipes are in the way) paddock stands may be the answer. And the rear paddock stand, the swing-arm stand, is always useful for any bike needing chain service. Do a little research into what you really need before you jump to a solution. 

And finally, in the category of "Damn, I should have bought one of these years ago!"...all of these can be very useful if not absolutely necessary...although using them tends to require more finesse and judgement than a newbie mechanic may have on hand. Fair warning, be careful with them.

• 5 Quart Pneumatic Oil Extractor (suck any fluid from anywhere)
• Snap Ring Plier Set
• A hammer-driven JIS impact screwdriver set
• A set of Punches & Cold Chisels
• A 24"-30" long "Breaker Bar" (a long handled 1/2" drive socket wrench)
• A set of plastic-faced dead-blow hammers
• A set of pry bars
• A set of files
• A bench vice
• A metric tap and die set (for cleaning out / cleaning up damaged threads)

I am sure this list seems daunting and it is by no means complete. I have lots more than this in my shop, but I have had decades to build my collection. Many purchases have been driven by a necessity that arises from a particular project, or the realization buying a new tool solves and old and often repeated problem. I am still buying tools. If I ever stop you can be pretty sure it was because I died. So...this list is designed to get you a good start, not be the definitive list of everything you will ever need. Just remember the home mechanic's motto: "No job is worth doing if it doesn't require buying a new tool!"

How do you know if your battery charging system is working? Check your battery voltage with the bike turned off. Start the bike. Check the battery voltage with the bike running at 1500 RPM or more. The battery voltage should now be higher that it was...and ought to be somewhere between 13V and 15V. If it is not, and particularly if your battery voltage is LOWER than it was with the bike turned off, your charging system has taken a powder. Now you need to figure out what is wrong with it.

One fun thing about motorcycles is that the charging system (which you would just call "the alternator" on your car) is broken into its two major components, so you can look at them (and repair them) independently.  The first part, the Stator (so named, I think, because it STAYS still while magnets spin around it) is simply (usually) three coils of wire that are located very near one or more magnets attached to the engine, so that when it is running, the magnets spin by the coils, inducing an electric current within them. (Yes, Virginia, that is how almost all the electricity you have ever used is made. Coils of wire are passed through a field of magnetic flux, causing the electrons within the wire to get excited and go flying off to some atoms further down the wire that are not quite so excited.) As you can see in this photo, the three coils are artfully arranged so that you would be unlikely to guess that there are three of them, but we know there are three and only three because there are three yellow (typically yellow) wires connected to the lot of them. How that works out will become clearer as we move on... 

The second part (Have you already forgotten there is a second part? I would have.) is the Regulator. The Regulator, as you might well imagine, regulates the voltage produced by the Stator. Because they are attached to the engine and the engine runs at wildly variable speeds, the magnets induce wildly variable current in the Stator, which is seen as wildly variable voltages on the output connector of the Stator (the three yellow wires).  What is worse is that the Stator is producing AC current (alternating current) while your motorcycle, and notably your motorcycle battery, operates on DC current (direct [unidirectional] current).  So when we call that second part of the charging system "the Regulator" it is shorthand for what it really is, which is a Rectifier-Regulator. 

What is a Rectifier? It is something that fixes (rectifies) something else. In this case, the "fix" is that it prevents electricity from flowing backwards. It converts AC current into DC current. In most cases, it is desirable to make use of both the forward and backward energy a Stator provides. When this is done, the circuit that routes Positive and Negative (forward and backward) current flow, so both get sent out in the forward direction, is called a "full-wave" Rectifier. And that is what is being done inside most motorcycle Regulators (a.k.a. Rectifier-Regulators).

Just to make matters a little more confusing, when someone says "Rectifier" they may be referring to the entire gizmo that plugs into the bike, or they may be talking about a single-junction semiconductor device with two wires on it.  Although the antiquated term for such a device may be "rectifier", for clarity, such a device is usually called a diode. And a module that accomplishes rectification, which is built using a number of diodes, may be called a Rectifier. The schematic symbol for a diode is shown below.  The message in the image is very literal. A diode allows current to flow in the direction the arrow (the triangle) is pointing, and the wall (the vertical line) blocks current that might try to come in from the right. If you went out and bought one diode off the shelf, it might look a lot like the cylinder with the white stripe shown below. The white stripe corresponds to the vertical bar in the symbol drawing. It shows where current cannot enter the diode. 

The several diodes in a Rectifier-Regulator convert the AC current produced by the Stator into DC current...but by themselves do nothing to make sure that the very high voltages produced by the Stator when the engine is at high RPM, voltages that can exceed 75 volts AC, do not fry the electronics on your bike or fry your "12 volt" battery. That job is handled by the other half of the Rectifier-Regulator (often simply described as "the Regulator").  Exactly how voltage regulation is done is beyond the scope of this post, and it may be done is several different ways, depending on the preferences of the folks who designed the charging system, but in the end, the Regulator will prevent the net DC voltage seen by your battery to be no more than about 15 volts. Typically "charging voltage", the voltage seen across the battery terminals while the engine is at 1500 RPM or more, is going to be around 13.5V to 14.5V DC. That is enough to make sure that current flows INTO the battery, rather than out of the battery (charging, rather than discharging). A good, ordinary lead-acid battery will show about 12.4V to 12.6V DC when it is charged and resting, so hooking a battery to a voltage source that is higher than that will charge the battery.

A Typical Charging System Schematic

This is a circuit diagram of a typical motorcycle charging system. The lines in the drawing are wires and when you see a round dot printed on top of the intersection of two lines, two wires, you know that those two wires are connected to each other. (Line crossings without a dot do not represent an electrical connection.) You can also see six diodes inside the Regulator-Rectifier module. The Stator is show as three coils of wire on the left side of the drawing. One end of each coil is connected to another coil and the loose ends are connected to the diodes in the Regulator. FYI - On many bikes, the three wires that run from the Stator to the Rectifier-Regulator (a.k.a the Regulator) are bright yellow.

Notice that each coil of wire in the Stator is connected to a dot between two diodes. Notice that the diodes are all pointed UP, showing that all the current flows toward the positive (+) connection of the battery...and on to other components of the bike via the main fuse and the main power contacts in the ignition switch. Notice that each wire from the Stator is connected between two stacked diodes, so that each pair of diodes does "full-wave rectification" of the current coming from each coil (each "phase") of the Stator.

The three coils of the Stator and the three pairs of diodes shown, along with the voltage regulating mechanism depicted by a regulator box and three switches (which are actually some transistors and other stuff) are the essential elements of what is known collectively as a "Three-Phase Charging System". 

WHEN THINGS GO WRONG

There are three main functions in the charging system;  production of electrical current by the Stator, rectification of the current by the diodes, and regulation of the voltage by the regulator circuits. Any of these three sections can fail or all of them can fail...and they can fail open (fail by disconnecting) or they can fail short (they can pass current to an unregulated degree or along an unsuitable path).

• Stator coils can break (open) or the insulation within the windings can deteriorate so current flows past a coil, through a shorter path (a short), rather than through the coil.
• Any one of more of the diodes in the Rectifier could fail open, so it fails to pass current in either direction, or fail short, so it passes current in both directions, so the diode acts like a wire rather than like a diode, as it should.
• And naturally, the regulator circuits, however they are implemented, can fail in ways that cause the charging system to produce too much voltage or not enough voltage.
  

​Fortunately, the Stator function and the Stator coils can be measured directly with a simple multi-meter, and the current flow through the Regulator (a.k.a. the Rectifier-Regulator) diodes can be measured as well...and more easily with a modern multi-meter that has a diode test function built-in (like mine does, more on that soon).

Testing the Stator coils is very easy. Unplug the Stator from the bike and measure the resistances between the three yellow wires...and between each yellow wire and the frame of the bike.  There should be NO current flow from any Stator connection and the bike frame (a.k.a. Ground), and the resistance seen between any two of the three Stator wires should be roughly equivalent...and pretty darn low...probably near 1 ohm. (But whatever DC coil resistance may be, the main concern is that they be about equal, say within 10% - 20% of each other.) If any Stator lead is shorted to ground (to the bike frame) the Stator is bad. If any two Stator leads show a dead short (~zero ohms) or leaks to the bike frame, the Stator is bad.

Testing the diodes in the Regulator-Rectifier is more complex conceptually, but not in practice. The Regulator needs to be unplugged from the bike completely. The DC wires (often red and black) and the AC wires (usually three yellow wires) need to be disconnected from the bike's wiring harness. Then each phase can be tested.

Sidebar: A Multimeter with a Diode Test Function

I use a very nifty multi-meter (that was not at all expensive) with some very useful functions, including Diode Test Mode. Note in these photos that the control knob is set to measure resistance but the meter is reading volts (!). That is because the way a multi-meter always test resistance is to send out a know voltage from inside the meter and then look at what comes back. Diodes have a very particular characteristic compared to other devices like resistors and light bulbs. While resistive devices will show a larger and larger voltage drop across their terminals as voltage is increased, the voltage drop across a diode will stay nearly constant, despite the fact the diode is conducting more and more current flow as the applied voltage increases. In Diode Test mode, the meter reports the voltage drop it is seeing across the device being tested.

• Silicon diodes always show about 0.5 volts of drop when they are forward biased (when current is flowing through them normally), as shown in one of the photos below.
• When the test leads are reversed, the meter shows "OL" or Over Load, which is not as bad as it sounds in this case. In this case OL means the reading is too high or too low for the meter to measure, or in this particular case, it means "this diode is reverse biased and no appreciable current is flowing", (i.e. this diode IS working like a diode and blocking current flow).
• To demonstrate a shorted diode reading I simply connected both leads together at one end of the diode. In this case, the meter reads 0.002 volts, showing that the test voltage supply coming from the meter has been shorted out and voltage has collapsed to nearly zero.

This is why it is so easy to test Regulator diodes with a meter that has a Diode Test mode (but you can use the resistance setting on a regular multi-meter too, it is just that the readings are harder to interpret).

Regulator Diode Testing

Connect your diode tester to a Stator wire and check for diode current flow through the positive and then the negative terminals of the DC output voltage connector. One of the DC terminals should show current flow...only one. Then reverse your diode tester connections and check the same points. Now the OTHER DC  terminal should show diode current flow while the one that flowed before should indicate blocked flow.

• If you show current flow in both directions from one Stator connection terminal to a given DC Regulator connection wire, the Regulator has at least one shorted diode.
• If current fails to flow in at least one direction through any given Stator terminal either DC terminal on the Regulator, the Regulator has an open diode inside. 

Repeat these measurements on each of the three Stator terminals, looking for results on the DC regulator terminals each time. ​

In the example shown here, current was found to be flowing from terminal A on the Stator to the positive (+) DC terminal of the Regulator (which it should) AND to the negative (-) DC terminal of the Regulator (which it should not). That measurement proved that this was a bad regulator. It must be noted that testing the diodes in this manner CANNOT conclusively prove a Regulator is good. Such a test can only prove that a Rectifier part of the Regulator is bad. The diodes could all be just fine and the regulating circuits themselves could be bad, resulting in bad system voltage on the bike. However, in this case, testing revealed at least one bad diode inside the Regulator assembly, so it is a gonner. 

Additional Tests

Once you have determined the major components of the charging system are functioning with the bike turned off, there are other tests you can do with the bike is running.

With the engine running AND the Stator unplugged from the regulator, check AC voltage between each of the three Stator output terminals (Three measurements...on the drawing above would be point A to B, A to C, and B to C). The voltage seen at any given engine RPM should be about the same for each measurement (because the coils and magnets are the same for each phase). You may see nearly 100V AC on these terminals, so be careful. Anything much past 24 volts can be noticeable and 48V and up can hurt...and can certainly be deadly​. Watch yourself. This test is particularly useful if the Stator is wounded and only shows a short at higher voltages or only shows an open when it is being vibrated by the motor. The key for each of these measurements is that under the same conditions, they should match each other pretty closely (say +/- 10%). Needless to say, if you see bad results in these tests, you have a bad Stator and need a new one.

Repeat the measurement of the AC terminals with the Regulator plugged in.  Again, each phase should be the same as another...although probably not the same voltages seen when the Stator was unplugged. Seeing generally lower voltages would be normal because the Stator is doing real work if it is plugged into the Regulator.  But be on the lookout for seriously low output voltage on any phase of the Stator. A bad Regulator may collapse the Stator AC output on any or all phases. One low or high phase measurement when the Regulator is plugged in, despite seeing uniform AC voltages on each phase of the Stator when the Regulator us disconnected, suggests a bad Regulator.

With the Stator and the Regulator connected normally, check the DC output voltage of the Regulator with the Regulator connected bike. For reference, check battery voltage first and keep that number in mind. Then start the bike and check battery voltage while it is running. Whatever voltage you see at idle should increase somewhat as you increase engine RPM but should stop climbing once it gets into the 14.5V to 15V range. If, when you are at 1500 RPM (high idle), it is not at least equal to the battery voltage you measured when the engine was not running at all, something is wrong (perhaps a bad Regulator, but possibly a bad Battery).  If DC voltage keeps climbing past 15V when you increase RPM, STOP THE TEST before you blow bulbs or worse on your bike. And get a new Regulator.

Disconnect the DC output of the Regulator from the bike and check Regulator output voltage while the bike is running, again slowly increasing RPM, checking to see how much output voltage increases as engine speed increases. If it is too low to charge your battery (say, less than 12.6V DC) or too high (say over 15V DC), you have a Regulator problem.

DANG…there is a leak…one stinking, little, slow drip…on the smallest hose in the system.  WTF.

Backwards? Well, yes. Normally it is the front wheel that goes into the wheel vice at the front of the lift. Why not this one? Because this bike needs a new front tire. The front end needs to come up off the ground, not the back tire, to service this bike...but that is not the whole answer.

A bike lift (a.k.a. a lift table) allows a mechanic to work on a bike without crawling around on the floor. If you work on a lot of bikes or are not 20-something anymore, a bike lift is a godsend. But sometimes, the bike needs to be lifted up from the lift table...the wheels need to be in the air, perhaps, as in this case, to remove a wheel and change a tire. What is a mechanic to do? The easy traditional answer is a small scissor jack, like the one shown in these photos:

The scissor jack is the little blue gizmo sitting between these two bikes and the lift table surface.  Capable of lifting 1000 lbs., it is very handy item to have. But there is a catch. The bike you want to lift has got to have some solid structure on the bottom for the jack to contact that can bear the weight of the bike as the jack lifts it off one or both of the wheels.  In the first photo, the rear wheel of an old Goldwing is being lifted while the front wheel is clamped in the wheel vice. It should be noted that this allows the bike to rotate (however slightly) about the front axle, without stressing any of the frame elements. In the second photo, the front wheel of a VTX is being lifted, while the rear wheel is strapped down to the table with the two orange "Y" straps shown and a matching pair out of view on the other side of the wheel. This allows the bike to rotate around the rear axle, without stressing any frame elements, yet, as in the first photo, the bike is being securely held upright, even as a wheel lifts off the table surface. But I digress. The central story here is the handy little blue scissor jack...and why it couldn't be used this time.

Here's the bottom side of the FZ6. No solid structure down there; nothing but exhaust pipes. Lots of bikes are like this...particularly sport bikes. Do not be the poor fool who lifts his bike by putting a jack under the pipes. You will not like the results. 

Sure, if we wanted to lift the rear wheel, we might get a jack to contact something near the back, like the pivots for the center stand...but to lift the front, the lift point needs to be in front of the bike's center of gravity...and that looks like a problem. Fortunately, somebody has solved that problem. We can use a "Head Stand".

Even if you hated High School Geometry, you are going to love a Head Stand.  A Head Stand us a wonder of geometry and the power of leverage. The stand has hinged uprights, a lifting pin at one end, the lever end (the hoop handle shown), and wheels that allow the whole affair to pivot as the hoop handle is pressed downwards.  As the handle goes down, the wheels roll forward and the pin is lifted upwards as the uprights go from folded, to straight and locked (as shown here). It takes a little effort, but not so much that even a skinny mechanic would find difficult.

The pin, as shown here, goes into the hole found at the bottom of the steering head on almost every bike. Those holes come in a variety of sizes, so if you plan to work on lots of different bikes, you get a bunch of different pins, not a bunch of different stands. The steering head is always located above the bike's center of gravity, so a bike will always hang securely from the lift pin, without any danger of the bike flipping over after it is lifted. 

The downsides of using a Head Stand are:

• the vertical legs can get in your way,
• the amount of lift you get may not be ideal for what you are trying to do.

However, since the front wheel will still pivot left to right, obstruction caused by the stand legs can mostly be avoided. Not having the ideal lift height is more problematic, which is to say, can usually be addressed with a little more effort and innovation (e.g.  you may need to do a little more disassembly than would have otherwise been required to get additional clearance, or you may need to slip something under the lifted wheel to reduce excessive clearance).

One word of caution: Head Stands should not be used alone...that is without some sort of REAR stand or clamp.  You might get away with using only the front stand, but you might not, and having a bike topple over just isn't fun. Use a rear stand or a wheel vice or some other sort of rear wheel tie-down to make sure the bike stays upright while it is being lifted. Yes, I know I said earlier that the bike's center of gravity is below the steering head...but it may not be far below, and if that is the case, removing the front wheel or the bike being jostled side to side might result in a tumble. So...play it safe. Secure the rear wheel before you lift the front.

Bottom line, Head Stands are a very useful and inexpensive tool...and one of very few reasonable ways to lift the front end of some bikes. If you need one, get one. You won't regret it.

A very pretty 2009 Suzuki V Strom 650 came into the shop last week. She looked showroom fresh, with less than 2k miles on her. Needless to say, she had been parked for years...and sadly, with a half full tank of gas...which, predictably, turned into a tank full of rust. 

The owner had already cleaned the tank and replaced some or all of the fuel pump assembly, which lives inside the tank itself, but despite these ministrations, she would bog down under load. She idled like a champ, but just wouldn't pull when the rider cranked on the throttle. Very frustrating for the owner. 

There are a number of esoteric possible causes for that behavior, but the most obvious thing to check is fuel pressure, which is a proxy for looking at fuel flow. This is a fuel injected bike, so fuel pressure is supposed to be pretty high, around 60 PSI. Fuel injectors just won't work right if the pressure gets too low. And if the fuel pump assembly cannot keep up with the fuel demand from the engine (as the engine control computer tries to get it to make more power), then the fuel pressure in the fuel supply line is going to drop.

Because spraying 60 PSI gas around your shop is a bad idea, selecting the right fuel pressure test rig is important. Fortunately, bike manufacturers have largely selected standardized fuel line fittings when they design their bikes. In this case one of the mid-size quick disconnect fittings was just the ticket and that allowed disconnecting the fuel line from the tank, plugging in the tester T-connector, reconnecting the fuel line to the Tee and then hooking up the pressure gauge to the open end of the Tee. The results can be seen at the links below... 

Start and Blip Throttle  and Advance to Higher RPM
​
What you see here is a significant drop in fuel pressure as engine RPM is increased...despite the fact that the bike is just sitting in the shop in neutral, not even spinning the back tire. So even with zero load on the engine, the fuel pressure drops...a lot. You might even notice in the second video that you can hear the RPM begin to drop (despite increasing throttle) when fuel pressure gets near 20 PSI. It is significant that the pressure drop is smooth. Pressure rolls off steadily as RPM increases. It does not, for example, spike low intermittently and then pop back, which might suggest an intermittent electrical connection to the (electric) fuel pump. Nope, this sure looks like plain old low flow. The fuel pump assembly just cannot keep up.

Now why say "fuel pump assembly" and not "fuel pump"? Because inside the tank there is not only a fuel screen / filter, there is also a pressure regulator, as well as the pump itself. Poor flow could be caused by problems with any one of them, not to mention the possibility that the fuel pump assembly components themselves may have been misassembled and are leaking fuel from the pressurized lines inside the tank into the low pressure area inside the tank itself. That would not produce a fuel leak that is visible outside the tank, but it could cause a pressure drop in the fuel line when fuel demand increases.

So, how did this all turn out? We don't know yet. Now that he has a solid answer on the fuel pressure question, he and his bike are back home awaiting the arrival of a new Suzuki OEM Fuel Pump assembly, which he will install after taking another good look inside that tank...to see if another cleanup is in order before installing the new pump. Stay tuned!

What does every mechanic want most? New wrench set? A better set of screwdrivers? Nope. In the middle of just about every job, at some point we say "Damn, I need one more hand!" 

Well, when it comes to changing tires, it couldn't happen more often.  Fortunately,  some bright guy came up with a way to add and extra "hand" and a very strong arm, to a tire changer. 

The need is pretty simple.  To demount or mount a tire, the sidewall needs to be pushed towards the center of the wheel. Some tires make that VERY difficult, particularly, low profile, high performance tires...the sort you might find on large, powerful bikes. With the advent of "helper arms" on tire changers, jobs that are very difficult with conventional tools become far easier...if not downright easy.

The helper arm, the black mechanism shown above, swings an air ram that is attached to a plastic foot, over a wheel and tire that has been clamped to the turntable. With the press of an air valve, the ram presses the foot down onto the sidewall as far as necessary to put the bead into the "drop zone" (the smaller diameter inner section of the wheel) which now gives enough clearance for the tire to be shifted sideways on the wheel, allowing the bead to be lifted over (demount) or pressed past (mount) the opposite side of the wheel. The arm is double jointed and the foot pivots, allowing the air ram to maintain pressure on the tire, even as the wheel is rotated on the turntable. Pretty nifty.

CLICK HERE to see it in action!

Much better... This is the result of about one gallon of gas left in a three gallon tank for five years. The nasty object above is the in-tank fuel pump and integrated fuel filters. That is pretty easy to fix. All you need is $500 and the time to remove it, rebuild or replace it, and reinstall a few bolts. Not cheap, but pretty easy. (Sure, you need to drain and remove the gas tank, which may require a pump and lots of disassembly time...and then you need to put it all back together correctly, but that isn't rocket science either.) The inside of the tank itself is a bigger problem.

The rehabilitation of rusty fuel tanks seems to be a religious matter. Doctrine ranges from "Don't...just replace it", to "Clean it and coat the inside with   (insert the name of some sort of paint-like product here)  ." And recommended methods for cleaning are all over the map too, ranging from "Rinse out the chunks and call it done." to "Fill it with  (wood screws, abrasive, BB's, etc.)  and  (shake it, tumble it, vibrate it, etc.) . I have tried some alternatives and today I generally take a middle of the road approach. I will say, if I had a big tumbler system or high powered ultrasonic wand that I could insert, I might do differently, but I don't. So I keep it simple.

1. Rinse out as much of the junk as you can with plain tap water.
2. Fill the tank with a gallon or more of Industrial vinegar. (This stuff is available from the big box hardware stores like Lowes. It is different from household white vinegar because it has a much higher Acetic Acid content than food grade vinegar.)
3. Agitate the tank (shake it vigorously) to coat all the inner surfaces with the vinegar.
4. Let it sit for a while, and agitate again, perhaps tilting the tank to a different angle so a different part of the tank interior can be covered with the pool of vinegar, and
5. Repeat...until you are satisfied with what you see inside (either because it is not getting any better or because it is perfectly clean...or because you are just bored with this step).
6. Drain the tank and rinse with clean tap water MANY times, even a few times after the water runs clean. Get all the chunks and all the vinegar out.
7. Dry the tank interior with forced air (air compressor, blower, hair dryer, etc.) and let it sit, preferably out in the sun, until absolutely dry inside.
8. Call it quits.

What you see in the photos above is the same spot inside the tank. The BEFORE photo was taken AFTER lots of plain water rinsing. The AFTER photo was taken after the tank sat overnight with industrial vinegar inside. There has been no brushing, no wood screws shaken inside, nothing but vinegar. It did not come out looking like new, but as you can see, it was tremendously improved.

I do not paint / epoxy tank interiors. I believe it is risky (the paints can degrade / flake off) and that fuel filters are really pretty good. Sure, keep a weather eye on your fuel filter(s) after you start riding again. If they start filling with rust then further intervention may be needed. But if you care for your tank with two final steps, that is not likely to become necessary. 

Step 9 - Fill your tank all the way on your way home from each ride.

The water in the tank does not (mainly) precipitate out of the gas. It mostly enters your tank in the form of humid air. Once inside, the water condenses out of the trapped air in the tank and falls to the bottom of the pool, where it does its dirty work. If there is no air space at the top of your tank, there is no water vapor to condense inside, and your rust problems are considerably reduced. Naturally there are other alternatives. You can drain the tank absolutely dry. That works too. 

Step 10 - Ride often. (Or at least run the engine for a half hour each week...and then top up the tank with new, not stored, gas.)

But here's a word of caution regarding that full gas tank. Modern Ethanol-mix fuel harbors bacteria that eat ethanol and piss Acetic Acid...which will eat everything metalic in your fuel system, especially aluminum parts.  Yes, I know I just recommended filling a rusted tank up with 30% Acetic Acid, but I also said get it all out when you are done. The bacteria in your tank are kinda slow growers, but if a tank has been sitting for a month or so, even a completely full tank, the bacteria bloom is underway and will accelerate exponentially over time until the bugs die in their own piss. If you have ever seen and/or smelled green fuel in a tank, you have seen the aftermath of a bloom for yourself.

If you are not going to keep fuel rotating through your tank (burning up the blooming bacteria and re-filling with fresh gas) then at least use a fuel preservative product like Stabil, to keep the buggers at bay for a few months. If it is going to be longer than that, drain that tank...completely dry.

(Full disclosure: water does come into the tank mixed in solution with the ethanol in the fuel. Water does not mix with gasoline, but it does mix beautifully with alcohol, as your bartender can readily confirm. And any batch of ethanol-gas you get may have water trapped in the ethanol. If you get a tank with high water content, the next tankfull is likely to dilute the concentration of water in the tank. Just another reason to keep using the gas in the tank regularly.)

So...either drain that tank dry or fill it full and burn some off every week. Don't give rust a chance. Like Neil says, better to burn up than it is to rust.

Internal combustion engines need three things to run. Fuel, Fire and Compression. If the correct amount of fuel (and air)  is in the cylinder, and the mix is properly compressed (to somewhere near 1/9th of it's uncompressed volume), and it gets a spark, the mix will explode. Physics. It cannot do otherwise.

Granted, lots of things need to happen properly in an engine for all that to come together and happen at the right time in the piston cycle, but that remains the core principle of internal combustion engines.  To troubleshoot an engine that is not running, or not running properly, those are the three main issues to consider. 

COMPRESSION
Lots of things can cause a loss of compression, but they all come down to the cylinder having a leak. Mechanical wear, blown gaskets, defective seals, dirty / leaky valves or bad valve timing can all cause a loss of compression. Fortunately, serious compression loss is fairly rare...and that is good, because it is always the most expensive problem to solve. Engines are built, first and foremost, to continue to hold compression through their service life.  The good news is that if you have verified fuel and fire, checking compression is among the easiest test to do on an engine. Still, it is rarely a sensible place to start your troubleshooting. Failures in the fuel supply and ignition systems are far more common.

FIRE
Outside of flat running out of gas, ignition failure is by far the most common cause of an engine failing to run.  And that is great, because it is the easiest problem to check directly and is often the cheapest problem to fix. The easiest ignition check is to unplug a spark plug wire, remove the spare plug, reconnect the plug wire, ground threads of that plug to the block, and crank the engine. If you can see a nice blue-white (or even reddish) spark you can PROBABLY  say ignition is ok and move on. I say "probably" because if you do see a spark, you still do not know if the spark happening at the right time. If you don't see one, you do not yet know why. Maybe the plug is bad,  or maybe other ignition components are bad and you still need to track that down (or maybe the kill switch is turned on!). But at least you know the next path to follow. But, there is actually something that is even easier to check, if only indirectly. And since we are trying to zero in on the main problem area quickly, easy counts for a lot. And the easy test involves the third leg of the stool...and is often a great place to start your troubleshooting.

FUEL
So, we have already assumed you are not out of gas...but on a small engine, you better make sure the fuel valve (often called a "petcock") is open and fuel is actually flowing. Next up on smaller machines, including most motorcycles, is the carburetor, which regulates the amount of fuel that is supplied to the engine under various throttle and load conditions. Larger, more sophisticated, less polluting, engines get their fuel via a fuel injection system.  Let's start with carbs. 

Carbs have tiny passages in them, through which tiny streams of fuel flow, that ultimately get mixed with the air coming into the engine. Just a little schmutz in any of those passages can put a carb out of commission.  A failed fuel pump or clogged fuel filter can also stop the music (in fuel injected motors too).  If your machine has been sitting for a few months with fuel in it, there is a very good chance your carb is plugged up and needs to be cleaned. But let's not jump to conclusions.

While you can look at spark plug and get a pretty good idea of whether or not it is sparking, you cannot just look into a carb and see whether or not it is working properly. Fuel injection systems in gasoline engines are almost always computer controlled, and with proper diagnostic tools, can often tell you if and why they are sick. But for a carbureted engine that has no blinky lights, it is not so easy. What to do?

​Well, obviously, you cheat. (And the cheat actually works on fuel injected engines too.)

One of the products you will find on the shelf at every auto parts store is a can of "starting fluid" or "starting spray".  The can will contain a cocktail of  flammable chemicals, usually including ether, which vaporizes easily and happens to burn like crazy.  A spray can of starting fluid is a great diagnostic tool. Remove the air cleaner so you have a clear shot at the intake, give it a one second blast of ether, and immediately crank the engine. If it fires and runs for a few beats (perhaps for a few seconds), you now know that you have reasonably good ignition, firing at (at least approximately) the right time. You know you have at least marginal compression. And you know that you just supplied the missing element...fuel, more specifically, vaporized fuel. (Engines do not run on liquid fuel. They run on vaporized fuel.) Now you have a pretty good idea where to look...the fuel delivery system. Ignition may not be perfect, but it was good enough to fire the ether. Compression may not be perfect, but it was good enough to explode the ether. So right now the fuel delivery system is the prime suspect. Conversely, if the engine did not fire with ether, you PROBABLY have an ignition problem and should at least do the easy ignition test (pull a spark plug and check for good spark). 

If you see good spark AND the motor will not fire on ether...well, now you are in for an education. It is time to dig deeper.

So...you aren't supposed to talk about religion and politics in gentele company, right? Well, I am going to put on my big steel-toed boots and stomp right into the middle of a hot religion topic in motorcycling...using car tires on motorcycles.

"What kind of lunatic puts a car tire on a motorcycle?", you might ask.  I cannot say with absolute certainty, but the evidence suggests to me that they are, at their core, shortsighted cheapskates; the sort who try to seal up a cavity in their tooth with superglue to avoid paying a dentist, only to reap an abscess and need dental surgery later.  

Why would someone even consider this insane idea? Well, motorcycle tires are not cheap, particularly not good motorcycle tires. And the labor charges to install them are often almost as much as the tires themselves. So it can cost almost as much to put two tires on a bike as it costs to put four tires on a car. That, understandably, rubs some folks the wrong way. Worse still, motorcycle tires may last 10k miles or even less, so they get changed much more often than car tires.  In short, tires represent a significant cost of ownership to a motorcycle rider.  

Nobody who has followed my work will be surprised I say that those who are not willing to pay what it costs to operate a bike safely, shouldn't own or ride motorcycles. But what are the safety issues? They all come down to the key mission of the tires...keeping the bike stuck on the roadway rather than sliding over/off it. Car tires present two obvious significant challenges to that mission.

TIRE PROFILE

So this is kind of a no-brainer. Bikes lean when they turn. They must lean to turn. The rounded cross section of a motorcycle tire produces a near-uniform contact patch (that part of the tire surface that is in contact with the roadway), no mater what the lean-angle  of the bike. The car tire, in contrast, has a rectangular profile and typically, very stiff sidewalls, so as the bike leans, the contact patch of the of the tire shrinks as the main body of the tire lifts off the roadway. Not good.

TIRE COMPOUND

The other big issue is the tire's grip on the road...traction. Traction and tread life are the core tradeoffs in tire design. Hard rubber wears off slower than soft rubber, but soft rubber grips better than hard rubber.  You may be able to visualize soft rubber oozing into the tiny pits in a paved roadway, while a harder rubber only makes contact with the tops of the roadway texture.  Some motorcycle tires, particularly those for touring bikes that do lots of highway miles, finesse this issue with a multi-compound design. The center of the tread area is made with a harder rubber for good wear when the bike is rolling straight ahead, but the outer portions of the tread surface,  between the center area and the sidewalls, are built with a softer compound that provides better grip when the tire is leaned into a turn. Car tires, which are not only designed for a heavier vehicle (and so have a harder tread compound for suitable wear in their intended application) but are also designed for a vehicle suspension system that is designed to keep the tire upright in a turn, making a multi-compound approach less useful.

BUT WAIT, THERE'S MORE

Or perhaps, there is less. In this case, less contact with the bead seating surface. "Bead" may be an unfamiliar term in the context of tires but here it is in a nutshell. It is the part of the tire that seats against the wheel and provides both the air seal that keeps the tire inflated but also provides the structural connection between the tire and the bike. The bead on car tires are designed to seat / seal / hold to the rims of car wheels (duh). The bead of motorcycle tires and seating profile of motorcycle wheels are different.  Perhaps they did not need to be, but bikes weigh much less than cars and the cornering forces placed on car tires are different from those put on motorcycle tires, so the tire seating region is smaller than is found on car wheels. Or to consider it from the other perspective, a car tire expects a different, larger bead seating region on the wheel, and therein lies the rub...or perhaps the lack of a rub. The seating surface on a motorcycle wheel is not right for a car tire. 

GOOD ENOUGH?

You may hear someone say, "But it works fine!". Well, that depends on your definition of "fine". Yes, as a rule, a car tire can be induced to hold air when mounted on a motorcycle wheel. And depending on the bike and the car tire selected, the tire will clear the surrounding suspension structure of the bike so the bike can roll. Let's even say that we are willing to accept the traction and handling compromises introduced by a car tire (I cannot imagine why you would, but let's say so, for the sake of argument.) What else is there to consider? What about emergencies?

DEFLATION EMERGENCIES

The car tire shown in this article came into the shop mounted on a motorcycle wheel. It did something very interesting when it was deflated. It spontaneously dismounted itself from the motorcycle wheel. That is to say, the tire bead became unseated from the wheel without any additional force being required. OMG! 

If you have never mounted new tires on car or motorcycle rims, you may not be aware that, once seated on the wheel, removing that tire from the wheel requires considerable side force. Getting the tire unseated  from the wheel is the main mechanical challenge in any tire change job, followed by the challenge of getting the tire off the wheel after it is deflated and then, finally, by the difficulty of getting the new one onto the wheel.  That may not sound surprising...but the first item on the list is critical from a safety point of view.

If we do not know anything else about tires, we know that they sometimes go flat. But we also know that they rarely come off the wheel just because they have lost air. Yes, a massive blowout can shred a tire and leave you with a bare wheel, but that is rare and virtually never happens to tires until they are used long past the end of their service life. On a car, a tire dismounting from a wheel causes damage to the wheel and perhaps the bodywork. It could even cause a loss of control and an accident. However, on a motorcycle, it WILL cause a loss of control, and that, for motorcyclists, is often deadly.

SUMMARY

Of all the hazards a car tire presents to a rider, the most insidious is the risk of a low pressure spontaneous dismount of the tire. Because car tire sidewalls are made for much greater loads than motorcycles offer, an inattentive rider may be on an under-inflated tire without realizing it. The tire may not "go flat". However, at some point, as inflation pressure continues to fall due to a small leak, the tire may no longer keep its grip on the motorcycle wheel. That dismount event is most likely to occur when the rider enters a curve...and is most likely to occur when entering a high speed curve. How's that for a nightmare scenario?

Granted, motorcycle riding is not an enterprise for seriously risk averse folks. But it is an enterprise that tends to weed out the reckless. Using a car tire on a motorcycle may not get you killed, but it absolutely lowers your chances of survival. It's not worth it to me. Make your own call. (But I will never mount one for anybody in my shop.)