Sled Wont Start and Backfires

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winslow14

New member
Joined
Jan 20, 2011
Messages
8
Age
30
Location
Fairfield,Maine
Hi, I have a 2000 Yamaha Vmax 500 DLX, It will not start and it backfires about every 3 pulls. I have pulled the spark plugs out and they had a black liquid on them. I cleaned both of them and cleaned them with a wire brush. I put them back in and tried to start it and it did the same thing. I took the plugs out and they were black again. What can i do?
 
Clean the carbs, replace the plugs, and when the plugs are out pull the motor over to be sure it's not full of fuel(flooded) already.
 
you have to take carbs off the sled and disassemble cleaning the inside jets and passeges along with outside.
 
Remove all jets and the fuel screws, spray carb cleaner thru all holes and then use a blow gun to blow air thru everything also.
Remember where the fuel screws are at for turns out and reset.
 
winslow14 said:
Hi, I have a 2000 Yamaha Vmax 500 DLX, It will not start and it backfires about every 3 pulls. I have pulled the spark plugs out and they had a black liquid on them. I cleaned both of them and cleaned them with a wire brush. I put them back in and tried to start it and it did the same thing. I took the plugs out and they were black again. What can i do?
Click to expand...

Winslow14, was your sled running and then started backfiring as the motor stopped?
If so it could have holed a piston, hope it's not the case but thought I'd better mention it as trying to start it with a holed piston would flood the motor and can result in a fire.
 
We took it out about 2 weeks ago and drove it around the house. We turned the sled off so we could make a little path, when we tried to start it again it wouldn't start, we thought it might of ran out of gas so we put some gas in. But it still wouldn't start. Ever since then it has been backfiring and not even starting. I cleaned the carbs last night and i am going to try to put them back in today. I hope its not the piston.
 
Sounds awefully like the ignition timing is off if it's backfiring, culprits are usually a sheared flywheel keyway or a faulty CDI box...
The plugs are wet because the fuel is not burning.

First verify you have a good clean blue spark... If all good then next remove the recoil, rotate the crank to put one of the pistons @TDC, check if the trigger notch on the flywheel is near the ignition trigger coil, if it's a ways off then your flywheel / timing has moved and you need to replace the keyway.
Keep us posted with feedback.
 
Last edited:
k so i cleaned the carbs and put them back on. It started and stayed running for about ten minutes but then it bogged and shut off. When i tried to start it again it made a very loud backfire. What is wrong now.
 
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