Sorry. I know there are tons of threads on jetting, but I couldn't find one that did the trick for me. I have an '87 xr600r with a Supertrapp exhaust and UNI air filter, and I just got a '96 xr600r with a White Brothers exhaust. I live out in the desert, at about 2500' and the temperature varies dramatically from summer (100's) to winter (50's). The '96 seems to be running lean with it's current jetting, which I assume was good for summer. Hesitates slightly off-idle and the plug looks a bit grayer than I would like. Previous owner said the main jet was a 165, but I haven't looked yet to be sure.
So, is it common for people to re-jet for summer/winter? Are there good references for jet sizes, needle settings, and screw positions for various altitudes and/or temperatures?
The recommendation I have received for the '96 is to
back out the idle screw 1/2 turn
raise the needle one notch
bigger main jet (167.5? 170?)
Does that sound about right? Is the idle screw on the '96 an air screw or a fuel screw? The above would suggest fuel. Any suggestions for the '87? Seems like it'll be a bit more complicated with the dual carbs.
Also looking for a manual for the '96. My understanding is that the xr600 was essentially unchanged from '88 to '98. I sometimes see manuals available for '88-'91 or '88-'92 ... that should work, right?
Sorry for all the questions, and thanks in advance for any help/suggestions.