Hello everyone, hopefully someone out there could help me...Have an 07 KFX 50 for my son. Have owned it for about a year, and last week I noticed that I had to rev up the bike alot in order for it to start moving. Before only minimal gas was needed and the bike would start taking off. Also now the bike only reaches a top speed which is much lower than before. Thank very much

 

I haven't worked on one but, from the parts book, it has both a centrifugal clutch and a variator. Firstly are the brakes stuck on? Sounds too obvious, but I regularly service bikes that have had the brakes stuck on for months and the owner has ignored it. If it rolls OK when pushed by hand, you probably have a belt drive problem, either the belt is shredding or oil has got into the belt box. Remove the belt cover and take a look. If the belt drive is OK, I would get the workshop manual and check the centrifugal clutch.