Just buy the full gear set from ebay and toss that in the bike. I'me guessing you're looking into a 2000-2002? Double check me on this but i think you can drop in the gears from a 2003-2005. If so i would go that route. Should spend about 200-300 on the gears, if that much. Or you can just buy the whole car kit for a few hundred more and use the old engine as a spare. Swapping the whole motor shouldn't be hard at all.