chinese 110cc atv engine sputters at higher rpm's. please help
Hello everyone, I am new here just signed up.
I have a chinese atv with a 110cc engine, I just replced the gear set in the tranny cause fourth gear lost some teeth, it is a 4 speed. So it seems the throttle response is not good in the mid to upper rpm range, also once it gets to about mid range rpm it kinda surges, like a lawn mower with governor problems, it goes and the cuts out, goes and then cuts out. Giving it a surging or intermittent sound. also it backfires alot, don't know if this is due to my tin can muffler or not.
So I just bought a new Mikuni 26mm carb for it cause they said it would improve the acceleration and speed etc. Also purchased the 26mm intake manifold and ported my head intake to 23mm. I made a custom air filter for it, it is basically an electronics project box approx 4.5" x 2.6" with a uni foam filter cut to fit, the box is mounted in the front of the atv. From there I have 2x 1.5" flexible
tubing the routes to a Tee on the carb intake. I have tried no air filter and restricting the air going in to see if I had to much filter area, but still the same problem. O, and also if the bike is in neutral and I open the throttle up all the way it will rev up pretty high then start doing what I described earlier, it also seems that it spits a little out of the carb intake when it sputters. There is no fuel adjustment screw on this carb, but I know you can adjust the mixture by moving the clip on the long needle that is inserted in the top of the carb, I just don't know if it needs to be adjusted or which way to adjust.
right now I am running 17t front and 25t rear sprocket.
Any help will be greatly appreciated.
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