these motors are good motors but i beg the differ on the comparision to the werks b5/b6. I own a b5 and my father a ss21 and theres a big power and runtime difference. the b5 will walk all over this anywhere on the range, especially on the bottom end. while the b5 will get 10-12min runtime AVERAGE we can barely get 10min which still is GREAT for a $150 motor. we have already had to replace the front bearing as it started to leak and have had to buy new o-rings in the carb as they were too loose. But it is still a great motor for the money and should last a while.. but it just doesnt compare that well to the power and runtime of the werks b5