Just mounted my new 79cc motor runs great with one small problem can not get over 20 mph on it engine just seems not to be willing to go faster and still have more throdle left it just acts like the more gas I give it the more it bogs down . If I stay at about 18 to 20 mph it runs fine . Has good power up hills , good even idle speed just no speed over 20 mph . This is my second motor on this bicycle the first was a 50cc I wore it out almost lol decided to up grade .