HELP! My motorcycle stopped working! What now? (How to run a FULL DIAGNOSTIC)

on January 14, 2020

So your bike is just not working? It’s time to get inside there and see what's going on. In today’s blog post, we cover all the steps you need to take to diagnose your Honda Shadow’s issues. (This works for all motorcycles, actually!)


- - -


“Help! My Honda Shadow stopped working! What do I do now?”


It’s time to run a diagnostic. If you’re new to this, we’re here to help. When running a motorcycle diagnostic, the key components of the diagnostic tree to remember are FUEL, SPARK and COMPRESSION.


Now let’s get started!




First thing’s first: check to see if your Honda Shadow is getting fuel. Start at the gas tank. Is your gas cap properly vented? Start your diagnostic here because it’s the point where fuel first enters your bike. Is the gas cap open? Is it plugged?


Next, check your Petcock. Is it plugged? Is the fuel line pinched? Is the fuel filter full of crap and thus not letting anything flow through? Is your float valve stuck? Is there a bunch of garbage in your float bowl?


Open the float bowl drain screw and see if there’s fuel coming out of the float bowl. If there is, that means you’re getting fuel to the float bowl. However, that doesn’t necessarily mean it’s getting pulled up out of the carb into the cylinders (where the explosions happen, allowing things to move forward).


Next, check to see if you’re getting fuel in the cylinders. If you’re firing up your Shadow and nothing is happening, you can usually smell fuel in the exhaust or in the pipes. If you get to the point where you’re just pumping and pumping but not getting any spark, then you’re “washing” your cylinders—and that’s bad. Normally, gasoline that enters into the cylinders is going to be combusted with the air, creating the power to move the pistons and give you forward motion with your motor. The walls of your cylinder are actually coated with oil. If the gasoline gets continually sprayed in there and just sits on the walls, it will eventually end up washing the walls of any oil. When you soak the walls in gasoline, you lose your lubrication. Then the rings of your pistons will start scraping raw metal. This is not good. And then you also have the problem of having gas in your oil. If it gets past the rings into the crankcase then you’ll have to flush your entire crankcase.


If you’ve gotten this far and still not found the problem, the next step to investigate is “spark.”



Now is the time to check your battery. Honda Shadows typically do not like anything less than 12v for startup or running. If they have 11.8v (which doesn’t seem that far off of 12—it’s not), they’re a little persnickety and won’t want to run well. You’ll be on the freeway and the bike will get up to full boar then die all of a sudden – you’ll wonder why and it’s because it doesn’t have full voltage. If your battery is 2-3 years old it may be time to change it.


If that checks out, then check your fuses. If the fuses are bad, then nothing goes past them. From there, it’s a matter of making sure your coils are getting spark. If they are getting spark and you have fuel, then you could possibly have a compression issue and you’ll need to do a leak down test on your Honda Shadow. If you don’t have a kit you can take it to a shop; it’s not a hard procedure to figure out on your own, though. A leak down test will help you determine if you’re having issues with your rings, if you’ve got scoring in the pistons, if you’re getting blow by (losing compression in your cylinder into either the crank case or past the valves), etc.



Now, on to compression. If you are losing compression in your cylinders, then it’s either going to manifest itself through excessive pressure coming out of your crankcase breather or you’ll feel pressure coming out of the exhaust. If you do a leak down test or pressurize the cylinders with an air hose and the motor is not turning over, then that’s an indication you have a problem with your compression.


Want more info on how to run a total motorcycle diagnostic on your Honda Shadow? Watch the full video here!



- - - - - - - - - - - - -
Looking for something else? Explore our Honda Shadow collections below: 
Want more how-to's, tutorials and other chop info for your Honda Shadow? Visit our Knowledge Base! Go to and click "Support."

Are you subscribed to our YouTube Channel yet??? GET ON THAT SHIT!!! Go here and hit "Subscribe": 
We're on Facebook and Instagram, too! Make sure you're following us!