Main jet is too small. Did you recently make any changes, say, remove the lid off the air box, or get the cylinders ported?

-cleartoy

 

Cleartoy,

thanks for your reply. the main jet being to small does make sense. yes some modifications have been made before this started occuring. when i first got the quad, the compression in it was almost gone, it was clearly in need of a rebuild. so i had the motor rebuilt by a local guy, and the cylinder wall was in bad shape, we had to bore it .080 over and put wiseco's in it. would this require using a bigger main jet? how much would a bigger main jet cost? and are the hard to install? as you can tell about all i know about the engines on these things is the normal maintence stuff. thanks so much for any help.

Chris

 

yes that would require a bigger jet and they are only like 2-3 bucks. there easy to put in if u know your carb. if not take it to a shop and have them do it.it shouldnt cost that much if u bring them just the carb.

 

The main jet works between 3\4 throttle up to full throttle.

If it is too small(lean) it will not operate correctly at the throttle settings i just mentioned.

Bigger pistons will require "A" bigger jet. How much bigger? No definite answer. You need to take into consideration, your altitude, humidity, what did it run good with before, what mods have you made since then,.....and so on and so forth. Its basically hit and miss, unless you can find somebody that has the same bike with the same mods as you. Thats rare, but its happened to me before , and i got my jetting perfect.

cleartoy

 

Thanks guys for all you help on this. This afternoon I played with the idle adjustment screw for a while (on a tip from another friend), and got it running alot smoother. it only bogged down 2 times in a 30 minute period, and then it was with the throttle wide-open and in 4th gear. does adjusting this screw make any sense about solving this problem to you guys? thanks.

Chris

 

UPDATE: Re: Need Suggestions

Hey guys, just wanted to update everyone, and thank everyone for helping me out on this problem, i took it to the repair shop, and they installed a bigger jet in the carb and now it runs like a demon! thanks!

Chris