What Do I Check When My Motorcycle Won't Start? - Honda Shadow Forums : Shadow Motorcycle Forum

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Old 06-19-2007, 07:00 PM   #1 (permalink)
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Default What Do I Check When My Motorcycle Won't Start?

I collected all the suggestions from other riders, and my own experiences, and put them into this post. I hope it helps! - Dan


What Do I Check When My Motorcycle Won't Start?

A motorcycle engine needs three things to start: Battery, Fuel, and Ignition. Any one of these three will prevent your bike from starting. We will address each of these, but remember that some of this information may not apply to your specific motorcycle.

While we cannot address every possible reason why it will not start, we can cover the basic things you can check yourself, with just basic hand tools.

In all cases, if you are not comfortable with getting your hands dirty and tearing things apart, then arrange for a reputable mechanic to work on it and save yourself the aggravation.

Many of us have had a brain cramp and overlooked that one really simple thing; and while these might seem obvious, before we get into troubleshooting, there are a few simple things you should check before you start taking your motorcycle apart.

ē The fuel petcock is on, and there is fuel in the tank
ē The ignition key is in the On or Run position
ē The Kill Switch is in the Run position
ē The Kickstand is up
ē The transmission is in Neutral

If the bike wonít start, you will have to investigate further.

THE BATTERY

The battery must be fully charged, especially if it is a new one. Most battery manufacturers recommend you slow charge the battery overnight. If you donít already have one, a trickle charger or Battery Tender is a good investment; as is an inexpensive voltmeter.

With the engine off, the battery should read in the vicinity of 12.5 volts. When the engine is running, it must be rotating at roughly 1,500 rpm or faster before it will begin to charge the battery. With the voltmeter still attached, rev the engine and you should see a reading of approximately 13.5 volts. If it does, then the charging system is operating correctly. When idling, the motorcycle is running off the battery, and if you let it idle too long, it could exhaust the charge in the battery, and the engine may die.

If you press the starter button and the engine turns over, but does not start, then the problem is most likely NOT the battery. If you press the starter button, and nothing happens, then the battery may be dead, OR you may have neglected to do one of the basic things, like turn the key on, or put the kickstand up.

FUEL

Make sure you have fresh gas in the tank, not some stuff left over from last yearís riding season. If you are not going to drain the tank for the winter, then make sure you use one of the commercially available stabilization products like Sta-Bil or Sea Foam.

If you have just tried to start the engine for the first time in a while, then the possibility exists that your carburetors may be gummed up from sitting. The appropriate amount of Gumout or Sea Foam may help; but if it doesnít, you will probably need to remove the carburetors, disassemble them and clean the gunk out of them.

Make sure the fuel petcock is turned to the proper position. You most likely have an On and a Reserve position on the petcock. If the tank is low on fuel, you may need to put the petcock in the Reserve position. If you have cranked the starter, and the engine does not start; check to see that you have not flooded the engine. I good indicator of a flooded engine is if you can smell a strong odor of gas near the carburetors. You can also remove one of the spark plugs and check the electrodes to see if they are wet. If you smell gas, or the spark plug electrodes are wet, you may have flooded the engine. If so, then make sure the choke is Off, let the bike sit for a bit, and try to start it again, this time without giving it any throttle.

If you do not smell gas, and the spark plugs look dry, then you may not be getting any fuel. Your gas tank may be equipped with a fuel line filter, either near the petcock assembly, or somewhere in the fuel line itself. Check them to make sure they are not dirty or clogged; if so, replace them. Your gas tank may also have a vent line which may be plugged or pinched. If it is, the engine will not be able to receive fuel.

Remove the gas filler cap, and if you hear a hissing sound, like air being sucked into the tank, then the vent may be the problem. Try starting the engine again. If it starts, then shut it off right away and resolve the vent problem. There have been reports that clogged vent tubes have caused the gas tank to buckle or collapse due to the vacuum created in side the fuel tank by the blocked vents.

If everything looks OK, and you have a can of starter fluid or a spray can of carburetor cleaner, you can try spraying a small amount into your air intake, the try to start the engine. If it fires up, but then dies right way, then you are probably getting spark to the plugs, but not getting fuel to the carburetorsí and you may have to tear them down and clean them. Do NOT keep spraying stuff into the air intake; you may damage the engine that way!

If you still canít get the engine to fire, then you may have ignition problems.

IGNITION

There are 2 basic ways to check to see if you spark plugs are firing. You can leave the spark plug installed, and pull the rubber boot from the plug. Stick a screwdriver into the rubber boot, making sure the end it touching the connector inside. Hold the shaft of the screwdriver about 1/8 of an inch away from the engine block and crank the engine. If the ignition is sending juice, you should see sparks jumping the gap between the screwdriver and the engine. This will tell you if the coil is delivering spark to the plugs, but it wonít tell you if the plugs themselves are bad or not.

An alternative method is to pull a plug, check to make sure that the gap is within the manufacturers recommended specification, and then connect the boot to the plug again. Hold the electrode against the engine, then crank the started and see if you can see spark jumping the gap of the plug. You probably want to hold the plug wire with rubber handled pliers, unless you enjoy getting zapped.

If you donít see a spark, then you may have ignition coil problems, or other issues. Find the location of the coil on your bike, it may be under the fuel tank, and make sure all wires are connected correctly.

Using fresh gas, new plugs, choke in the off position, try starting the engine. If it still wonít start, then you will need to check for things that are outside of the scope of this post. If your motorcycle starts and stays running, then itís time to celebrate and go riding. Donít get too far away from home though, just in case you missed something.
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Old 06-20-2007, 10:41 AM   #2 (permalink)
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A fourth element is crucial as well.

AIR

Too much or too little air intake into the engine can cause a motorcycle not to fire. As vacuum sucks air through a carb it pulls fuel from the float bowl while the jets atomize it and then the mixture continues through to the combustion chamber. If there is an intake leak or other vacuum leak that is sucking air into the combustion chamber without fuel then the mixture is wrong and engine will sputter, run at an extremely high idle, or not run at all.

Causes for vacuum leaks
  • Poorly installed carb or intake manifold
  • Vacuum line disconnected or broken

Too little air would be a blockage or a super dirty air filter and should rarely occur but is something easy and simple to check if the bike is unknown to the mechanic.

--BB
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Old 06-20-2007, 11:45 AM   #3 (permalink)
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awesome post. it seems we've hit a rash of the "can't starts" recently and this'll be useful to all
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Old 06-20-2007, 12:41 PM   #4 (permalink)
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Quote:
Originally Posted by tmyoungjr
it seems we've hit a rash of the "can't starts" recently and this'll be useful to all
Yep, that is why I put this post together.
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Old 06-28-2007, 08:58 PM   #5 (permalink)
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bearkatbiker,
Do you know if there Is there a vacuum line on my 1993 VT1100c and if so where would it connect to? (both ends). I know, dumb question, but if I don't ask then I will never know.
Thanks,
Winddrifter
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Old 06-29-2007, 09:40 AM   #6 (permalink)
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The schematics show it going from the carb assembly to a valve assembly but not sure what the valve assembly is, but I'm going to assume that your bike has a vacuum operated petcock so in this case there would be a vacuum line running from he carb assembly to the petcock mounted on your tank.

If this line is broken you will not only have a vacuum leak but you will also not be getting fuel from the tank.

Typically on any car or motorcycle vacuum lines will be attached either to the carbureator directly or to the intake manifold. On most japanese motorcycles the carburator is attached directly to the heads, eliminating the need for a manifold so rubber lines coming off the carburator would be the first place to check.

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Old 07-26-2007, 09:18 PM   #7 (permalink)
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Default kill switch

I know this is dumb but I have actually went into panic mode when my bike would not start and all it was was the kill switch was off. I always kill my motor using the key. While my bike was parked someone flipped my kill switch......it took me about an hour to figure it out!
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Old 07-26-2007, 09:32 PM   #8 (permalink)
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Just like mounting from the right side, it's a belief around here that shutting down by only using the key is REALLY bad luck!
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Old 07-26-2007, 10:54 PM   #9 (permalink)
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Default well then

I'll just have to berak that habit right away!!!
Thanks cause I had no idea.
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Old 07-29-2007, 04:49 PM   #10 (permalink)
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Hey folks! Quick question from a 6 year rider, 1 month tinkerer. I have an 01 750 A.C.E that wont start this year. New battery, getting plenty of spark, had some old gas in the tank over the winter. I added new gas and some seafoam, but didn't drain the tank. I traced the line from the tank to the in line filter just below the tank and onward. Is this bike equipped with a fuel pump? Is that what the cylinder tucked low in the frame is that has one line in and another fuel line out? The out line goes all the way back up to the carbureator. I am just wondering if maybe my pump is out. I sprayed Starter fluid into the carb and it fired for about a second then died again. I have done this several times and get the same result.

the air filter is new as well. I haven't done anything with the carbeurator though. I am not that tech savy yet.

I have 2k miles on it. I live in MN and we don't have long riding seasons, plus two littel kids have kept me from the bike as much as I want.

any help would be great! Thanks in advance.
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