The Yamaha Raptor 660 is an all around great machine, it has tons of power and is very reliable on the track as well as in the bush. But, there are a few problems that must be underlined before you buy this machine.
The 660 has a few design flaws, there was consumers reporting that the starting one way-bearings are wearing out faster than it should, this is a pricy fix it will cost $130-$300 depending on what you want to replace, usually you should replace the bearings and the 52 tooth gear. Another problem to underline would be the relay, people have reported a buzzing noise coming from somewhere on their machine, I have had this happen to me and it wasn't untill i replaced all the electronics on my bike that I figured out that it was the relay, having a dirty relay will cause a poor connection to your battery and it will not charge properly, over time your battery will die and this is what the buzzing noise is. Throughout the years Yamaha has not changed the swing-arm on the raptors design, some may argue that it is better but it reduces the clearance and handling performance on the 660, other manufacturers like Polaris have adopted all around suspension. Other forums that i have visited have talked about the stator not working correctly. If you go to start your 660 and it does do anything or if your driving or letting it idle and you're hearing spitting or sputtering then it is probably your stator shorting out. To temporarily fix this problem you can unplug your rectifier situated at the back of your quad. For a note on how to take your stator out visit this link http://www.raptorforum.com/forums/showthread.php?t=30801 Another reason for not starting may be caused by the carbs getting gummed, to fix this clean them out, the carbs are made much to small for the size of the engine so jetting them out might help. Any other troubles starting or running may be caused by insufficient gas flow through the carbs to fix this play with the idle screw situated at the bottom of the carb, unscrew by 1/4 turn and keep on playing with it until it sounds right. Be careful to not tighten or loosen too much and be sure when you turn your handle bars when your ATV is idling that it does not speed up while idling, try turning your handle bars and if it revs up re-adjust the screw until it doesn't rev as this could be dangerous.
All in all the 660 has minor problems but which ATV doesn't? This is a great machine with a lot of potential. Any questions or suggestions about this article will be much appreciated.
I posted a few pictures of my Raptor 660, what do you think of it.