I have 99 Wolverine 350, nice bike but here is my problem.

Slow pickup through pilot jetting but when gets to needle goes like hell.
I've tried changing pilot jet to bigger and smaller, adjusting mixture screw - nothing!
Actually it got worst when I changed pilot jets, so, I'm back to original(42.5).
Then, I've installed dyno jet kit, main jet is now 150, needle at 4th grove and mixture screw 3 turns out.
I'm in Calgary, so I've figured I should be using 150.
No change in low range. I think got power (mid/high) but bike now backfires.
Tryied 3th and 2nd grove, well.. bike was going nowhere, it lost all power.

Is there anything else I could do?
How about adjusting valves? Would that help?

What other ATVs are the same as my Wolverine?
I have searched many different forums for some solution but unfortunately didn't get much.

Any help greatly appreciated.

 

Have you checked the rubber diaphram in the carb? If that has a rip or small hole, it'll really cause some issues.

 

I had it out many times but didn't notice any holes or cracks.
This weekend I am going to do a compression and leak down test and also check float level.
From what I have find out it be should set between 11.4-13.4. Can anyone confirm that? It is Nikumi or Mikuni or something like that. [img]i/expressions/face-icon-small-smile.gif[/img]

 

Does the problem get better or worse when you pull the choke part way out?