Originally Posted by qwertydude (Post 524044)

The crankshaft will have no problem spinning that RPM and many more. It's the other components that will beg for mercy long before the crankshaft.

The valves will give out long before then. There's a thing called valve float. You'll make this problem worse with high lift cams. If you know a little about old school muscle car tuning you know that high lift cams actually lower your redline due to increased valve velocity. So you're not gonna reach 10k RPM's AND have high lift cams. Simply not gonna happen.

You also need stiffer valve springs to be able to use high lift cams properly without hitting valve float earlier which means even shorter valve adjust intervals which will happen quite often because of the Chinese pot metal that the valve seats seem to be made of. And go too high on the lift and you can easily hit the piston. You're better off replacing the head with big bore valves than going with higher lift. You'll get more performance that way without shifting the powerband to unpredictable areas due to unblueprinted mystery cams with unknown cam lift, duration and overlap.

Slapping all the bolt on parts you can get your hands on without the necessary tuning expertise is an exercise in futility. Lots of people have gone through bolt-on-itis without realizing much if any gains over a well tuned stock scooter and the downside being they've also reduced reliability.

And who's porting the head? Unless you yourself are an expert in tuning and have access to flow meters and other professional tuning aids you're not going to see any benefits from backyard "porting".

Start with the basics for power. CVT tuning, BBK, then intake and exhaust and carb tuning. After that pretty much everything else bolt on adds minimal if not immeasurable increases in power. The professional tuners in Hawaii and Puerto Rico who know what they're doing put a lot more work than bolt ons to get their incredible outputs. You're talking custom milled and decked heads, forged pistons, 4 valve heads, custom programmed CDI's etc.

Carb tuning is one of the most important skills you should learn too since it's going to be the one skill that makes or breaks your engine literally. Get the tuning right and it'll scream, too rich and your power simply won't be there, too lean and you blow a hole in your piston. And don't bother with the 22mm carb unless you're getting a true 22mm slide carb. A 22mm cv "performance" ebay special carb is nothing but an 18mm carb only partially drilled out so the front measures 22mm and the rear only 18mm. This makes for a difficult to tune carburetor due to abrupt flow changes in the airstream.