Mojaveracer - you should really try to rejet properly. On the main front page of this website you can select tech connection. Go there and click advanced search, then select carbs and all quads. It will give you a straight forward way to make sure your jetting is correct. You will have to read for a while, cause all the replies don't state exactly how to jet from the main all the way down, but keep reading.

Like I said before, the mojave is really hard to dial in, it took me a while to do it with the stock needle (no clip adjustments), I had to cut some rubber out of where the air intake starts. I would guess that with a K&N clamp on - it would serve you best and I would strongly recommend to go to a dealership and get a needle with the same specs (length, taper, etc.) that has adjustable clip positions.

You're rings getting fried after putting on a K&N clamp on (especially if you didn't rejet after you put it on) points to a lean running engine. Boiling over is a banshee problem, not a mojave problem.

ogre

 

I did rejet after putting a K&N clamp on filter. I went from a 147.5 to a 152.5 main, raised the neadle another 1/8", and went from a 35 pilot 2.5 turns out to a 38 pilot 3 turns out. Jetting is almost defanitely not my problem because today I put my stock airbox back on and kept the jetting the same as it was with my clamp on and it din't help the overhating problem one bit. It ran perfect before when I ran the stock airbox and much leaner jetting. The next thing I am going to replace is my thermostat. Also I am going to get a timing light and check too see if my timing is off. I beleive that if youre timing is too advanced it can make your motor overheat. Just because most mojaves may not have boil over problems doasn't mean mine doasn't so please try to help me ogre instead of accusing me of not knowing how to jet my machine.

 

Mojaveracer -

I'm Sorry I sounded a bit harsh - I didn't mean to come off that way. And I certainly didn't mean to insult your intelligence either.

I wasn't sure if you had rejetted after the K&N, given you're getting lots more air in now. I thought for sure that could be a problem.

I'm really not sure what else to think - but its possible that your thermostat is faulty, like you said. If its stuck wide open the coolant doesn't have a chance to cool enough before it re-enters the motor. I'll think about it though.

ogre

 

I am sorry for taking my anger out on you ogre. I was just realy pissed off yesterday about my quad and anything could have(and did) set me off. I have found something else that may be a sign of a problem. I was trying to read my plug by running the motor for a long(about 1/8 mile)straitaway wide open and then cutting the ignition while keeping the carb full throttle. When I did this I noticed a verry strange thing. Every time the ignition cut as I hit the rev limiter it back fired and it backfired verry bad when I cut the inition and pulled in the clutch. I must be pre-igniting or something like that because there is no spark to ignite the mixture when the rev limiter hits or the ignition is shut off. I know backfiring when you let off the throttle means your piot is lean but have no clue what backfiring at full throttle with NO spark means. The fuel must be igniting on it's own somehow. I have just totally cleaned my head and piston so I can't imagine it being carbon built up. I don't think it is ignition either because how can it be ignition when it is turned off. My only gueses would be lean jetting(which I dought) or my cam timing is slightly off. I am lost here please help!