110cc atv engine acting up

[Brianator]

Sounds like you're having a rough go there fella! Backfire out of the carb is typically due to the crank/cam timing being out of whack which believe it or not, valve lash can play a minor role in that. When you're cleaning the carb are you spraying carb or brake clean through the orifices? My go to for physically cleaning jets and small orifices are bits of guitar string, they are stiff enough to not fold under pressure but flexible enough to get into awkward spots. Another big thing to consider is spark timing so it might be a good idea to check the flywheel/magneto key, if it's even partially sheared it will throw the timing off.

 

[ghost civic]

I bought new carb for another quad, and it came with an extra spacer.

So I put it on the bike, and this took care of the rev hang. I was also able to turn out the mixture screw out, pretty close to 1.5 turns out total. Apparently using the old spacer with 2 fiber gaskets was not making 100% seal...though it was a big improvement over using just the old spacer which allowed the bike to rev really high.

But the bike still would die if you hit the brakes.

I tried adjusting the needle height up (richer) and that was worse. So I put it down and now it doesn't die from hard braking.

However, it will still stall out after idling for 30-60 seconds. It is 55 degrees outside. I am probably just going to sell it as is, since it is runs good, starts right up, has plenty of power and stays running. I bought it just to sell it in the first place.

I did look into seeing if I could adjust the transmission to engage at a higher rpm...so I could have the idle higher. While there is what looks like an adjustment on the outside of the case, it didn't seem to do anything other than lower the rpm at which it engages.