BC belt skip?

[Bikerbob]

Hey folks,

Running a Mr-4bc with a 4300kv novak in it.

84/23 gearing (but that does not seem to matter)

No slipper - stock drive train.

IF I punch the throttle I get a dull crunching sound which I think is the belt teeth skipping over the drive gear.

IF I roll on, I can still go full throttle .. but no crunch.

Starting from a standing tone start, I get it, if I dont punch I am getting hammered by the guy behind me..

I have installed an extra tensioner further up the top deck, but I think this is an issue right at the centre drive gear.

Anyone have a suggestion besides .. dont punch it?

OH I can PUNCH the throttle when the car is already rolling.

James