Hey guys, I have worked on several quads over the years. And owned many as well. I am stumped on this one...

Bayou 300 2wd. Sat for 4+ years bought it for $35 thinking easy flip, rebuilt and cleaned carb, new plug, choke cable, battery, o ring between boot and cylinder, adjusted valves, changed oil etc.

I got it to run for awhile but would not rev pass 1500 rpm, replaced the vacuum diaphram on carb bc it had a few pin holes in it, now it just cranks over.

I have 170 psi compression, good spark, fuel in the carb but air is not drawing it into the cylinder to fire.

I can take the boot off the carb, put hand over carb throat and it feels like its blowing instead of sucking. Take boot off of cylinder and it sucks down pretty good. When,it was running last I sprayed starting fluid on all the boots and no rise in idle. Any ideas? Sorry for long post, but more info is better than little. Thanks

 

One thing about quads that nobody notices until they are working on them and have the airbox off is they blow from the carb as well as suck. I assume it is due to fairly "wild" cam timing, so the valve is still open a bit on the start of the compression stroke. I also assume the vapour expelled by this, is sucked in at the start of the next inlet stroke. Anyway, it is nothing to worry about. 170psi compression seems awful high though. I once had a KLF300 with a badly worn cam, the exhaust valve hardly opened, so gasses couldn't escape, it wouldn't rev and the exhaust glowed cherry red in no time.