RGM Belt drive

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I've always set mine up without the side plates on the engine sprocket. When I get the slack correct and it runs true (dual adjusters) I put everything back together and my belts last years. I'm using a Gates HTD belt with a Norvil kit 36/72 ratio.
 
This one jumped the keeper plate as suggested by Chris.
 

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Some info here on the Bob Newby Racing belt/clutch I recently bought for my 650ss.
I know it's not in the same horsepower league but may be relevant and/or of interest.

The belt is black with round tooth profile - it is Gates Powergrip (made in UK) HTD 976 8M - see photo below.

RGM Belt drive
 
I've been using Bob Newby's belt drives on race bikes for three decades now, and have never had a problem with them. I think they are about as good as it gets for belt drives.

Ken
 
Yes with Goodyear HTD or Gates powergrip GT2 belts (available in the US & UK etc). No failures in 30+ years. I ran them on my 850 monoshock and now on the street. 40mm is best for an all out race bike. 30mm is fine for the street with an alternator. These were the 1st belts that could stand up to the job and the 1st to become popular.
 
I have that same 976 belt in 40mm wide on my bike, and actually bought the current belt from Bob. No problem with the old belt, race bike, they get changed......and I always carry a spare.....racer do that!
 
robs ss said:
Some info here on the Bob Newby Racing belt/clutch I recently bought for my 650ss.
I know it's not in the same horsepower league but may be relevant and/or of interest.

The belt is black with round tooth profile - it is Gates Powergrip (made in UK) HTD 976 8M
Click to expand...


How many teath on pulley and drum?
 
Back from the national rally...

It is known the R&L gearbox adjusters are recommended as better than the RH only. In reality the LH side alone is actually adequate but more difficult to use. The adjusters holds the bolt NOT the tranny case.
It is also known the case through hole is (IIRC) 1/32 oversize from the bolt. Same with the bottom.
At the suggestion from drag & road racer/bike builder Carl Hockensen, in 1988 I fabricated, for my combat, a custom bolt on mine to take this up...no slop or movement possible
It is also known the rear chain has much more power to pull the tranny to the rear than the otherway around.
Hole shots and power shifts will often tighten the primary chain or belt because the gear box moves but not the top or bottom bolt.
Just a possibility plus when the clutch basket grows when hot....
 
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swooshdave said:
Instead of a custom bolt would a sleeve been better?
Click to expand...

A sloppy part fit can potentially be everyone's problem...or not!
If one chooses to remedy the potential problem, then the solution is based on the available material and machinery, and the skill of the operator. That tends to dictate the style of the solution.
The custom bolt would likely work in every gearbox case, assuming they were likely all made the same.
A custom sleeve would be a lot of work for one housing only....
 
By sleeve I think we are saying bushing. It wouldn’t need to be custom to any one gearbox. Drill the hole out slightly over size and press the bushing in. Because the ID of the bushing would match the bolt there’d be no movement.

Is there slop, um, I mean clearance in the adjuster for the oversized bolt?
 
Has anyone already said push the gearbox forward with the adjuster/s, against partly tightened bolts, then tighten the bolts?

Then the adjuster can play its part in the tug of war with the rear chain.
 
Most common problem I see is as Triton Thrasher says.
You must use the adjusters to fully tighten the belt and then snug up the trans bolts.
Then use the adjuster to move the trans forward until you have enough play.
You want to have a block of wood wedged in the rear chain to hold it tight when you check the belt tension, to take up the play in the sleeve gear.
The you finish torquing the trans bolts.

If you use the adjusters to tighten the belt and then simply torque the trans bolts the pull of the rear chain will move the trans back a little further and take up the slack in the mounting holes.
This will over-tighten the belt.
Then you will end up with what you have the first time you run it hard.
 
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