when I start my 01 raptor 660, the engine runs fine, but there is a grinding noise comming from the starter, on lower RPMs, when I rev it up it stops (disengages) than i let RPMs to go down and the noise retuns, any ideas?

If your starter is stuck in the engaged position and pushed back by high RPM and allowed to come back out when slower it might do what you describe. If the noise is coming from your starter I would pull the starter and bench test it. Also check the solenoid if it is separate from the starter.

ill take the whole thing apart this weekend, I hope its nothing expansive, but knowing my luck...