I`m workin on a 70cc k-star right now. I think it`s a pretty good cilinder.. with great potential for more power. The porting is very low, so when you raise the cilinder by 22, the "timingen" (do i say it right? port-timing maybe?) will be higher. Now you can make your exhaust port bigger and hogher. My blowdown is 25, and an exhaust timing of 180 degr, so a calculated exhaust will work fine on it.
A k-star kit normally has lots of torque, but the high end power is low. Cause of the low port-timings you can make it really fast, you got enough "freedom" to make it to your own needs.
Also the 70cc k-star is a reliable cilinder.
Most of the guys in the netherlands have this set-up:
- 70cc k-sar
- 15mm bing cab/17.5mm dellortho/19mm bing/21 dellortho
- Leovinci or poma exhaust.
This is the cilinder im working on:
I hope you can use the info.. ;)