I have a 2005 Yamaha Wolverine. I installed a Noss Machine air intake adapter with a UNI filter, a FMF Megamax II exhaust with all 9 discs and no quiet core and a dynojet jet kit. I followed the dynojets instructions and installed a 160 main jet and the needle on the forth clip. With jetting at this setting the machine popped, sputtered and hesitated at half to three-quater throttle badly, so I changed the main to a 155 and the needle on the third clip, now it would sputter and hesitate, but not nearly as bad as before. I took the airbox lid off and the sputtering and hesistation are gone and the quad runs real good. I checked the spark plug and even when it was running rich the insulator was still just a slight off white color. Has anyone else run into this problem with a Wolverine and a FMF Megamax exhaust.

 

I just finished putting the FMF kit in and I believe it is the same as the Dynojet. I think Dynojet makes them for FMF to sell. Anyways I was given the same specs as you and it is a Great improvment! Best money I ever spent. I will need to test ridie more as I only took it up and down the block once last night and did not get a chance to run it out comletely. I did notice that on deceleration it popped a tiny bit out of the exhaust so it might be a little rich? (if anybody else can help please chime in) When I was tearing the carb apart to give it a good cleaning and check the diferent parts before assembly with jet kit I noticed that I was missing a couple of parts probably from the previous owner which explains the stripped screw all over the carb. I am not saying you are missing parts but rather just check to make sure the stuff is in the right order or that maybe a pice of dirt did not get in one of the jets or that the float height did not get accidently adjusted? I say this because your discription sounds like what mine was doing before I went through every thing.

Good luck and I hope you get it sorted out.