1986 Yamaha loses power and dies.

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Jun 5, 2006
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#1
Last week my buddy and I went out riding. I had a terrible time getting my bike to start...Finally it started and was idling fine. But when I gave it gas, it sputtered and died. I asked my dad and he said it could be the fuel filter...So I took that off, put some water through it, then used an air compressor to clean it out. After cleaning it I put it back in and it was still doing the same thing....So I just took the fuel filter out and used a direct hose to the carburetor. That fixed the problem! So after riding around for about 20 minutes, I'm cruising along in 3rd gear, dropped it to second and the engine starts to sputter and then finally died. I haven't been able to start it since. When I got home I drained the carb, cleaned out the jets (they look fine though) So my dad and I tested the spark plug. ZERO spark. Nothing. I even bought a new spark plug to test that. Still nothing. Whats the deal???? I've check all my connections, my battery is good.... My dad says I should have a blown fuse somewhere??? I looked in my manual but I couldn't find anything about a fuse.... Could my coil be bad? Maybe my floats in my carb??? I really have no idea... I've had soo much trouble with this bike its not even funny. I just want it to run.... :bang:


Help, anyone???
 
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#5
This happened to mine. Had to have the valves adjusted and the hot start button wasnt sealing. I dont know if a 88 has a hot start but o well.
 
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#6
I just got my hands on a 1978 TT500 and was having the same problem, Take the carb off and check to see if the jets are clean if they are it could be your air\fuel screw it might need to be adjusted. After that was done to my bike she ran like she should.
 

ghunter

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#7
If you are getting no spark, cleaning the carb won't help although knowing the carb is clean will at least let you rule that out AFTER you get it started.

You may want to try another new spark plug just in case the other new plug was bad. For a few $$ it is certainly cheaper than just replacing parts, and you can always use another plug as a spare.

Get a service manual for your bike and find the recommended process and results for checking the various components of your electrical system.

Being that your only statement is "no spark" it is hard to diagnose where in the electrical system the problem could be.
 
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#8
I tested my spark (another new plug) again, this time with a meter. Nothing. Its completely dead. I've checked all the wiring and checked for dirty contacts. Everything checked out.

Right now I'm thinking its either my CDI unit or my coil... Whats it more likely to be?
 
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#9
JohnRaven.exe, its most likly to be a coil. They made CDIs because they are bullet proof. your best bet for parts would be bikebandit, or bikeboneyard.
 
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#10
Alright, thanks man. I think I'm gonna take my bike to the local dealer so they can make some 'official' tests. Thanks for your guys help!
 
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