My son's KFX 90 makes a popping noise when he has it really torqued up (climbing hills mostly). Anybody got any ideas on what this is? It's usually 2, 3 or 4 quick pops like something is slipping. Also any tips on getting more out of it? It runs around 30 on top and comes out of the hole quick enough for his current skill level but I might want more one day.

 

Is this the 2007 model or the 04-06 KFX/LT80?

Regardless, I'd clean the carb just to make sure it's not got a jet plugged. If that's ok, try raising the needle a notch.

 

Is the popping from the exhaust or a mechanical type sound?...By LT80s response I'm thinking he means if the popping is coming from the exhaust because of an engine miss..

 

Unsure Yeller. [img]i/expressions/face-icon-small-smile.gif[/img]
with the suz-kaw split, kaw went on it's own for 07 (90% sure) so this could be a 4 stroke which would effect a recomendation.
I always start with a carb cleaning as it's easy and no cost.

 

This is the 07 4-stroke. It has less than 5 hours on it and has done it since I took it off the truck. Its a mechanical noise and is worse when I put my 195lbs on it. I only hear with my son when he is going up steep inclines. Sounds like something slipping.

 

Valve lash not correct????
Jetting??
it only does it 2-4 times then is OK or by then is he up the hill?

 

Yea i had the same prob i found out it was the chain slipping off the back clog it never popped off just slipped therefor making a popping sound.