seasonal tuning

[Rancher2005]

What do most of you do to your atvs to make the transition between seasons. I ride in the Northeast where there is a huge difference between a 90 degree day with 70% humidity to a winter day in the single digits with low humidity. It would be nice to just put the airbox lid on in the winter and take it off in the summer and change the jetting as little as possible. Throw out some suggestions.

[yernkie]

I live in Kansas and we go from 100 degree summers to single digit winters. All I do is drop my main jet down a couple of sizes and it seems to work great. I also threw in a 42 pilot jet last fall and it helps a lot with cold starting in the winter.

[GPracer2500]

The airbox lid idea could work. Might be too big a jump though in some cases. A main jet change and a fuel screw adjustment is probably a better idea, IMO. Most people are probably fine leaving the needle alone. This is mostly because a the main jet circuit has enough overlap into the needle circuit to keep things acceptable. If you get any surging at constant throttle (in the 1/4 - 3/4 range) then that's an indication the needle circuit is too lean.

One main jet size richer for every 25 degrees cooler is probably in the right ballpark. For the fuel screw, just try turning it out a little (there's a thread in the "How To" section if you really want to get it spot-on).

The fuel screw is kind of a pain to get to, but remember that if main jet changes take more than 5 minutes, you're probably not doing it the easiest way.

[Rancher2005]

I am becoming slightly proficient with the main jet changes using the 17mm access. The pilot is not so easy although I put in a 42 recently. I don't think I have enough mods to justify it. (A UNI with airbox lid on) Starting has always been a pain. Now that I have the 42 in it is just as difficult. Not sure how many turns out , but not far(maybe 3/4-1) I am running a keihen 152 with the needle one notch richer than stock . I was happy with the way it ran(with the exception of starting); at 70 degrees a week ago. But when I ran it at 40 degrees I wasn't too thrilled. When I lugged the engine(a gear too high with almost WOT) the engine would want to stall. Not sure if it is lean or rich. It doesn't bog at WOT when in the proper gear though. I would just ultimately want to find a system that works for me to jet between seasons, and want to stay away from Dial-A-Jet for some reason. Does everyone just rejet almost everytime they ride?