I bought a 2001 raptor, and it has black soot on the spark plug and the exhaust is black. I'm pretty sure that it is running rich, I'm new to the whole 4 stroke scene, so if anyone could help me correct this It would be appreciated. I know that it needs to be jetted but I have no idea how to do this. And I don't know what all this 150/155 means.

Thanks,
crazymedic

 

Make sure the black stuff is not burning oil first. Why do you think its got to be rejetted? Does it have some bolt-on power goodies? The "150/155" would be jet sizes. These are little nozzles in your carb that you can change to get more or less fuel to your engine. You probably have to take the bottom of your carb off(called the bowl) and the "jet" will probably be a little brass piece with a little hole thru it. The jet size should be stamped into the jet. Never done a Raptor 660 so maybe someone else will be more helpful.