2005 49cc zuma transmission problem?

[jesse]

please help! My little zuma is not reaching top speed and is shifting strange. I have owned 3 separate 49 cc zuma scooters and at the elevation that I live at they would all go 37 mph on flat ground. I recently bought another one "2005 49cc 2stroke" and it worked fine for the first week. Then it it would only reach a 32mph top speed and after 5-10 mins of riding it has acceleration issues. But the acceleration issue only happens after I ride it for 5-10 mins. I am mechanically inclined but for the life of me I can't figure out what the problem is. I pulled the fuel tank and cleaned it out. I removed the carb and thoroughly dissembled and cleaned it- it wasn't dirty. I replaced the roller weights witch were flat sided but the problem did not go away. I installed a new athena drive belt but the acceleration problem got immediately worse so I reinstalled the factory yamaha belt. Any advice would be great! Thanks.......

[bull]

run a proper compression test and, cylinder leakage test

[Firehawk989]

The factory yamaha belt is the best. Only buy those as replacements.

The big contra spring in your rear pulley has probably gone soft, which can mess up your acceleration. Get a new stock one, or a malossi white one as a replacement. While you're in there, make sure the two sliding sheaves of the rear pulley slide smoothly and easily. If not, disassemble, clean, and repack with grease.

If your belt is worn down near or past the wear limit, you will start to lose top speed.