1987 Yamaha YFM100 champ wont' run unless spray spark plug
#1
1987 Yamaha YFM100 champ wont' run unless spray spark plug
Got a 1987 YFM100 champ that my 10 year old rides. Recently it got very hard to start. In fact, it won't really start. I replaced the fuel filter and it didn't help. I pulled the plug and sprayed carb and choke cleaner on the end and replaced it. It fired right up. It doesn't run great but runs well enough to ride around the house and as long as you are riding it, it keeps running. As soon as you stop and let it sit for a few minutes, it won't start back. If I spray the spark plugin again it will start.
Any idea what might be wrong with it?
Any idea what might be wrong with it?
#2
Got a 1987 YFM100 champ that my 10 year old rides. Recently it got very hard to start. In fact, it won't really start. I replaced the fuel filter and it didn't help. I pulled the plug and sprayed carb and choke cleaner on the end and replaced it. It fired right up. It doesn't run great but runs well enough to ride around the house and as long as you are riding it, it keeps running. As soon as you stop and let it sit for a few minutes, it won't start back. If I spray the spark plugin again it will start.
Any idea what might be wrong with it?
Any idea what might be wrong with it?
#3
#4
Hi rykr, I have the exact same atv. That sounds to me like a fuel problem. Probably the air/fuel mixture isn't right. Since it runs after it gets started, it might just need a set screw adjustment. Another possibility is bad or contaminated gas. When I had a similar issue it ended up being that I had an extra o-ring in one of my set screws that wouldn't let it close in all the way. They're super small and easy to miss. Maybe start with checking your gas condition, clean the carb, then play around with your set screws to see what works (always remember where you started for reference).
Hope this helps.
Hope this helps.
#6
I see. Your spraying the plug trying to "prime" the starting, not cleaning the plug. Sounds like a fuel delivery issue ( as another had mentioned ) and probably time for a good carb cleaning/rebuilding.
#7
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#9
Earlier posts were almost certain to be no compression due to valve clearances needing setting, common problem with little Yams, or an air leak due to cracked inlet manifold, if it can't suck through carb you don't get fuel into cylinder. However if you are not getting a spark when engine is hot, most likely a stator coil gone bad, either power or pulser coil, and as you have replaced pulser that leaves power coil.
#10
Its fixed
The issue with having to prime the plug with carb cleaner was resolved, I replaced every ignition part on mine or so I thought until I actually found a service manual. Turns out it after spending 400$ on CDI, COIL, and Pulser it was actually what is called a source/charging coil. which is located behind the magneto. you will need a special puller to remove the magneto. The coil and new seal was 61$. you will need to solder it back on and be sure to cut the wires very close to the old one! Ive included the service manual on testing the ignition system and the part number/name below.
3GB-15451-00-00 GASKET,CRCS COVER (Yamaha) $15.02 Available Thursday, October 29, 2020 5G3-85520-M1-00 COIL,CHARGE (Yamaha) $33.22 In Stock