jets/reeds
definetly talk to a mechinik. only trust parts-guys to look up part numbers. if you have a hard time telling if you are lean or rich, the plug reading can be one measure of how the bike is jetted. if its black, you're rich, if its white you're lean. you want the insulator to be coffee-ground brown.
when i rode a 2 stroke, after break in i'd buy 4 cheap plugs. i'd jet the main, then put in a fresh plug, jet the needle (stock usually will do, just concentrate on the clip position), then change plug, then jet the pilot (with the air screw in the middle of the adjustable range). Change the plug and rejet the main one last time as this circuit is the one to most likely do the most damage if it is too lean.
I'd try to run on the verge of lean for most power. (which = less longevity typically) When done I'd throw in a spendy racing plug. Make sure to check the gap, they are usually good, but its really easy to check.
When I used to have pro circuit port/polish my motors they recommended the following treatment for reeds. Buy an extra set of stock reeds. They happened to be about the cheapest and were carbon fiber for my bike at the time. Remove the metal stops (not sure if atv's have these) that back up the reeds. Cut the old reeds 15mm from the center line of the mounting holes. Then install the new reeds with the cut down ones backing up the new ones. (Taking the place of the orig metal stops) Just watch for the corners chipping on carbon fiber reeds. Make sure to use loctite when re-installing the reeds. You will probably need an impact screwdriver to remove the stock ones too or you'll probably strip out the screws heads.
Make sure your silencer is packed, your pipe isnt smashed, you're jetted and do the PC reed treatment and the atv will be very responsive and will be hard pressed to load up or foul a plug. Run 32:1 oil too, its cheap insurance. Its the only lubrication your big end bearing, wrist pin bearing, etc get... Less oil (ie 50:1) is RICHER! (more fuel to air, becuase there is less oil, now gas takes the extra space) So if you choose to run less oil, make sure you jet accordingly.
