i have a 1998 600 rmk, with twin PSI pipes, modded airbox, boysen reeds,slp powerpack kit. i was wondering what or where i should start with the air fuel mixture ? it seems to have no bottom end but a whole lot of mid to high.
Run it WOT for 1/2 mile to 1 mile, stop as quickly as you can, pull the plugs out quickly see what they look like. They should be a tannish color. If they are black, your running rich, if they are white you are running really lean. Adjust from there.
Another method is to run it at 3000 RPM's for about 30 seconds while on a stand and continue on with the test.
With your situation, I would guess you are running leaner then you should.
*edit* - let the engine warm up a little bit before performing the test, as it is not only hard on your engine running it that hard right away, but can also effect the color of the plugs.
try going to a smaller pilot jet. the slp powerpaks increase low throttle velocity and signal strength and this can have the effect of pulling more or too much fuel through the pilot jets. with twin pipes you are bound to loose some lowe end power. try increasing clutch engagement also to get into the meat of the powerband.
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