2012 scrambler jetting?

[redrider022002]

im new to the forum but ive had polaris quads for quite a few years now. ive got a 2000 scrambler 400, 2006 and 2007 scrambler 500 4x4 and a 2012 scrambler 4x4. i took all 4 up to to the mountains at about 6000 ft this weekend and had problems with the 2012 popping badly and not wanting to run at all. but the others run just fine. my question is does anyone know what this could be other than jetting? my understanding was that the 500 engine setups were all the same. i just assumed that the new one would run just as well as the older quads. it did run a little better when i took the airbox cover off, but it still wasnt right.

[redrider022002]

well the dealer told me that the new ones have to be jetted to run at that altitude. might try a k&n filter before i have it jetted. anyone know what they changed for the 2012 model to make it need to be jetted. the manual says 6000 ft is ok

[scrambler2010]

A k&n will make it run leaner. I would think that if anything was changed with the jetting it would be a smaller jet (main or pilot) to have cleaner emissions. A lean engine will "pop" sometimes especially when letting off the gas. Is it more cold blooded when started cold then the older 500? This may be a smaller pilot jet issue. If running with less power and seeming to be sluggish then it may be a leaner main jet issue or both. Being at 6000ft it seems that it would be rich so the popping with the air box cover off is a little strange. I would put a new plug in, run hard for a few minutes, chop the power, then check to see the color of the plug. If blacker then rich. If whiter then lean. If nice cardboard brown then good. Any cam/valve noise?

[redrider022002]

no noise at all. it's only got 2 hrs on it. I took it back to the dealer and they couldn't find anything wrong. had them put a uni air filter on it (it still under warranty so I didn't want to screw with it) and that helped quite a bit. it runs as good or better than my older ones at altitude. funny thing though is my 2 smoke 400 is completely stock and I've had it up to 8500ft with no problems at all!