I bought this used from an older gentleman who barely used it less than 500 original miles and hours very low was like brand new. i have used it for last 2 years and rde it alot but not to extremes. so to the point 2 weeks ago i was riding and it started to die when you slowed down if your on it it was ok it would run but not like normal. I found a mechanic who makes house calls he came out looked at it cleaned lines and air filter , said i over oiled it when i cleaned it got it to run ..... not rite and dont sound rite. but said it was doing what it was supposed to do and left it at that. NOT EVEN CLOSE , top speed of 37 mph throttle hammered, smells like it is running rich, throttle has no snap. Hammer hell out of it it goes and sounds like its getting to much air, very throatie like a carbarated car with air cleaner upside down.Now noticed since guy worked on it cooling fan not kicking on, it runs and goes but thats it no GO any help ?