To get more power you need to pop the head and open up the bottomend,,
massage the ports,,ie: transfer ports,,intake port and exhaust port
add releif windows in the piston sides,,
reshape the piston sideskirt,,
deepen ring channel 1/32" and widen ring channel 1/64"
index the piston
deburr and smooth sharp edges from the piston edges
polish the piston,,pin bearing and pin aswell as rod journal
polish the cylinder
blueprint the fuel flow transition from the lowend to the topend to deliver maximum velocity by cutting off the corners from the cylinder skirt on flow side
take lowercase and port the flow side to run into the transfer port channels fast and smooth
reinstall the head without a basegasket to bump compression,,yamabond works great here...I use JB Weld...
lighten the flywheel
add a rocket key
mod and lighten the clutch
port the intake to match the newly ported intake
add a boost bottle setup
rebuild the carb with a real walbro rebuild kit..$10 bux on ebay shipped..
add a v-stack and hp airfilter,,,a detergent cap and pantyhose does a better job...........To choke the engine you just palm the opening shut and pull a few times the engine fires right up if tuned good..
There are a couple other mods you can do to make serious power
chop the cylinder top and turn it into a 2pc cylinder
do the full circle crank mod.......
add an expansion chamber to that exhaust pipe...
Then theres modding the CVT transmission by lightening the rollers so the variation becomes delayed enough to enhance bottomend takeoff immenseley....I reduced the total weights from 25.7 grams down to 20.8 grams...That reduction gave me a ton of takeoff......
Heres a thread to follow..same engine and its kind of guided by me..Im just giving pointers,,,hes doing the work....It adds depth to this post and should clear up most questions that I know are building...
http://www.pocketbikeplanet.com/showthread.php?t=79566