89 Yamaha WR500 doesn't spark continuously

[vinnie333]

I have a 89 Yamaha WR500 that will only spark for a short duration and then I lose it if I let it sit for a bit it may spark again or it may not.

I have been working on this for several days now and have not been able to come to a solution.

Can anyone out there help me troubleshoot this problem.

Thanks

[97GPSLEEPER]

Have you unscrewed the plug caps from the end of the plug wires to make sure you have good wire at the end? Alot of times it gets brittle and breaks, and you have to cut the insulation back until you get good wire again.

[vinnie333]

put new caps on but i did not trim the wire back. I will try this

[DANGER1049]

If that doesnt work check and see if you are getting power to the coil. Could be a bad stator or computer.

[97GPSLEEPER]

put new caps on but i did not trim the wire back. I will try this

I leave about 1/8" of bare wire sticking out.

[jdog800]

check for loose ground and or battery terminals and on the engine side. You would be suprised how many people who have electrical problems can try every trick in the book an overlook this simple but important piece. Intermitent electrical problems can be a result of looseing ground.
Another issue is trash making its way onto the pickups of the flywheel, which can also cause an short.
The other issue is the rectifier. A bad rectifier can send bad voltages back thru the electrical system and cause bad spark. Unplug the red wire off of the rectifier to test this problem.
The last thing I would mention is the lanyard. I have seen weak lanyards start failing where the clips dont hold the lanyard open enough and cause the ski to shut off.

I have had at least 20 skis this year come in for electirical problems and the majority of those were solved by the first issue bad ground. Jumping, normal use and vibration of the motor tends to loosen the ground on the engine block causing hell with the electrical system.

[w/rpm500]

connectors at the engine clamshell can go bad intermitantly on a w/r, check both white and black... the electrical box has been known to leak and get water,shorting out the box for a bit...(seen this on two wr's now) .
the switches at handle bar coud be bad..bypass these at the white and black connectors to verify their integrity...

a coil could be breaking down,leaving you with an intermitant start-run, no start, until it cools down...

let us know..

[DANGER1049]

Know that I think about I had a starter wire come loose on me last year, run for a minute than shut down.

[w/rpm500]

'dangers' right on there!!.. where the ground bolts onto the flywheel cover is a notorious spot.It goes green, corrodes the bolt or cover, then the cable floats around on the bolt,working intermitantly...

[Myself]

When my old WR500 did that it was the CDI.