I have an 04 Foreman. After a day of hard riding the bike started making a topend clicking noise and wouldn't run right. Sounded like a lifter. I checked the lifters, they were adjusted fine. Pulled the engine out and found the problem. The tensioner for the timing chain had broken which allowed the chain to flop around. Going to put it back together and do the gear reduction at the same time. Just something to keep in mind if your engine starts making a topend clicking noise. Done talking now.