The jackshaft really shines on the 97cc engine. It makes it fun to ride. If I remember correctly my stock new style bike is hitting 38mph with a 60lb rider. Not too shabby. I also kept a jack shaft on my predator build. More for the shorter chain lengths with no tensioner needed. I also like the easy gear changes for dialing in a gear ratio. In my opinion though it's a waste of $120. for a 212. I say that because I have a mbx11 with a 212 that I use the split sprocket adapter on. It's harder to swap the gear halves but once you find the right ratio you probably won't ever change it. It's a balance between take off and high speed I'm looking for. Too high a gear ratio you lug the clutch on take off and end up cooking it. Too low of a ratio and you'll have a wheelie machine that'll toss riders. Both extremes are fun in their own ways, but reliability and liability dictate my desire for the happy compromise. In my pursuit of happiness I intended to keep the predator in modified stock form but I was constantly running up against the governor which caused an annoying surging and then cutting down at full speed which annoyed me. But that's what a governor does. So several more $100. bills later that bike rides the way I want.
I love the hydro brakes. One word of warning though. In my quest for speed I had a catastrophic failure which made me reconsider the hydro brakes. At speeds over 40 the pads melt, the rotor warped, and the caliber snapped one of the mounting ears off. I'd love to see somebody manufacture a billet caliber. That said I still run juice brakes on the jackshafted stock bike and the 212 mbx11. The crazy fast bike I went back to a properly adjusted mechanical brake with heavy duty pads.
