I've got a 2000 Bear Tracker I'm working on. The guy said that it was running until they ran it through water and it backfired and would not start again. Yeah... customers tend to lie, but... anyway. I replaced the starter clutch set to begin with so I could see what else was wrong. I cleaned the kill switch and got it to spark. I rebuilt the carburetor - there is no way this thing was running, but... yeah. I have verified that it has compression (over 150psi). I have verified that there are no leaks (with a leak down test). I have verified that the cam is in time. I have verified that the valves are adjusted correctly. I have verified that the valves are in fact opening and closing. I have verified that the flywheel hadn't sheared the key (both when I replaced the starter clutch and I made sure that when the top-dead center mark is lined up, the piston is, in fact, at tdc). I have verified that it still has spark. It refuses to start. Even on starter fluid. EXCEPT... If I hold my hand over the intake, it has twice popped off like it wants to start, but that is it.

I am at my wits end! I would accept ANY and all tips, tricks or help, no matter how ridiculous or redundant they may seem. Please and thank you!

 

I would really appreciate any and all help on this, and if anyone see this,I got further information from the customer if it helps.... He said that they were riding it. He went to gas it to get through some water and it backfired, blowing a piece off the muffler. That was the last time it ran.

 

I assume you have tried a new plug. I always use butane gas from an unlit gas blowlamp rather than starting fluid, If an engine is getting too much fuel, any fluid will "wet" the plug and it won't fire after that, butane just vaporises off. Also, Yams are well known for inlet manifold cracks, which can lead to air leaks and bad starting.

 

lol... are you the one who replied on reddit? I only ask because I've heard twice now to use a blowtorch as starting fluid and that is **way** too coincidental!

 

No, I only post on here, Butane works well on petrol engines, tried it on Diesels and it doesn't seem to do anything though.

 

That is so weird! Anyway.. I did try that, as per someone else's suggestion!, and no go. I did try a new plug... three actually, just in case. The intake manifold could very well have leaks, but it should at least fire off on fluid, I would think.