I'm experiencing a slip then it grabs when I am on a road and I hit the throttle only when in 5th,, just a moment of slip then it grabs. No grind sound. This motor was freshly rebuilt and I saw no odd things on gearing or gear fork. I have put on 800 trouble free miles since rebuild. Does this sound like clutch or gears? Can't get it to do it in any other gear,, I recall a little slip last ride but I thought it was my foot not getting it shifted.