Stage 1 or 2?

mt bike is pretty much stock runs great, I was wandering what is, and whats the diff between stage 1 and 2 jetting?

regardless of what stage it is, the higher the number the more power derived from the kit.

let's say that you got a complete aftermarket exhaust, not just the end can, but the complete set from headers on back. because this flows more, you would need to rejet to a larger than stock jet to take advantage of the increased flow. this is usually stage 1 jetting.

stage 2 involves a bit more than an exhaust. say a hotter cam, head work, possibly increase in bore or cc's. and so now, to take advantage of even more power potential of the engine, a larger jet than stage 1 would be used.

all jetting does is balance out intake and exhaust flow. you don't want to run small jets on high flow machines and you don't want to run large jets on stock setups. if you run too big a jet, you will send too much fuel to the engine and end up with a rich condition (too much fuel, not enough air). if you run too small, you will end up with a lean condition (too much air, not enough fuel).