Post by usmcdoc on Jan 17, 2014 7:25:22 GMT -6
Put many 100BBK's on customer Scoots at their request and against my will.80 is plenty. The stock crank on all 3 of those ate the connecting rod bearing. For some odd reason..the ONLY 100 BBK I have used that did not ruin anything is the Airsal 100cc(50mm) BBK. It has a domed piston oddly and used the stock head nicely..in fact they recommend a stock head. 2 guys have over 4 and 5 thousand on their odometers and the bearings are fine! Awesome power too! After weighing the Airsal piston against the 'other' brand ones..I found they were lighter which must reduce the 'off balance' piston to crankshaft counterweight ratio which is most likely why the much larger piston kits ruin crank bearings. Also evident was cylinder and piston 'scuffing' due to piston flop..possibly from being off balance. Not seen that on the 2 Airsal kits. That being that the Airsal was designed as a BKK..NOT just a stock cylinder that was over bored and paired with a too heavy piston. Search Ebay for the Airsal.. or SPI Scooter parts. Their power output is incredible also..zip..zing..and you are gone.. 
Glenn
Glenn