Help identifing this belt drive kit? And should I just go back to stock triplex chain?

Belt drives need to run straight and they must not be too tight or the belt gets destroyed in less than 20 miles. Happened to a friend of mine. Your picture looks alot like my friends kit. Blew up just like yours. RGM sells a twin lollipop gearbox adjuster for controlling the belt to keep it aligned. You adjust the belt so you can twist it with your fingers 90 degrees on one of the runs. You adjust the twin lollipops to steer the belt. They also save a lot of reciprocating weight as opposed to the triplex chain system. Flywheel effect. They are also easier on your gearbox and gears. Once they are set, it a SET & FORGET deal.
Just remember Never too tight. That Aluminum clutch basket expands quite a bit when it heats up.
 
To add to the confusion: Looks like my RGM: front-28, rear- 54, Puller holes are 5/16" x 24... 517 Synchroflex AT 32 mm
 
phippsy said:
Looks like a RGM kit , did it have a plate on the front pulley to keep the belt in line? . RGM now do a 30 mm belt that is a lot stronger then the old 32mm easy swap .the new kits are 27 front and 54 rear , the 28 front gears it up and puts less pressure on the gearbox .
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Thanks, great info and yes it has a front plate. I already removed it to get access to the holes for the puller.
 
Deckard said:
It is probably a RGM belt drive. I bought a new one from BWolff back in 2011 that was advertised in our classifieds as a RGM.
CNW estart made installing it moot now,
It looks exactly like yours. Front pulley is 28T, rear is 55T. RGM site describes rear pulley as 54T, so may be a change from earlier version. Best to check with them if you plan on keeping this. M7 threads in front pulley for puller.
Same color belt. Belt labeling is "702 SYNCHROFLEX AT 10/890". RGM parts for their belt drive list that belt.
Wanna buy another belt 13+ yrs old? :cool:

Because the front pulley is tapered, follow shop guide of using a puller to place stress on pulley and strike pulley on the side to free it from the taper.
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Thanks for the good info. M7 is definitely not a common bolt size. Odd they didn't use the same SAE threads as the stock front pulley.
 
SteveA said:
No keeper plate on the outside?

Be very sure about the thread before you work with a puller. 8M is a far more typical size than M7 for anything, Use the wrong bolt and that alloy speocket will shed it's threads in a second.

I don't think I have anything here that is M7 and I have bikes and cars in metric only!

I have a Bob Newby front sprocket, no you don't have that, or a Norman White one which I also have. Newby uses M8, Norman I can't remember, but I think 5/16".

Steve Maney doesn't use that belt form, I'm guessing RGM or Norvil. But someone must recognise it.

A standard Andover Norton front sprocket puller works fine with the 5/16" bolts substituted with M8. Don't use any other method, or you will have a mess on your hands.

My puller has been slotted to make it more universal, not difficult to do.
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Almost everything on an Ossa is M7. It's really difficult to find , especially in the pitch used.
Other than the Ossas, there's no M7 here either.

Glen
 
DougBoost-I have a complete almost-new Norvil belt drive kit for sale (front pulley, clutch basket, clutch center, belt, 750 clutch plates-4 friction, 3 steel, pressure). It was just removed and replaced with a CNW electric starter that came with their belt drive and Barnett clutch plates. PM me if interested.
 
RGM claims the Red Synchroflex Gen III belt is stronger.

Roger's current lighter weight clutches don't look like that what you have. The basket is smooth on the back and the rear steel is not bolted in.

If planning to try it again... RGM sells the newer Gen III belt for a better price than any other place I have been able to source a Syncroflex Gen III. Unfortunately, shipping from the UK is not particularly reasonable anymore.

RGM's new front pulleys use 5/16-24 NF threads for the puller. Made mine out of a scrap piece of 1/4" alloy bar stock and two 2.5" 5/16-24 bolts. My RGM clutch is a lot newer that 20 years and the front pulley comes off easily.

Help identifing this belt drive kit? And should I just go back to stock triplex chain?


If you run an AT10 belt too loose it will slip and you won't be able to give the engine full throttle. Well, not my engine anyway. The 90 degree twist is too loose. Fiddly belt to set up. If'n I were doing it again I personally wouldn't use an RGM belt clutch because of that stiff slippery AT10 belt. That is just me though and I tend to swim upstream.
 
Schwany said:
RGM claims the Red Synchroflex Gen III belt is stronger.

Roger's current lighter weight clutches don't look like that what you have. The basket is smooth on the back and the rear steel is not bolted in.

If planning to try it again... RGM sells the newer Gen III belt for a better price than any other place I have been able to source a Syncroflex Gen III. Unfortunately, shipping from the UK is not particularly reasonable anymore.

RGM's new front pulleys use 5/16-24 NF threads for the puller. Made mine out of a scrap piece of 1/4" alloy bar stock and two 2.5" 5/16-24 bolts. My RGM clutch is a lot newer that 20 years and the front pulley comes off easily.

Help identifing this belt drive kit? And should I just go back to stock triplex chain?


If you run an AT10 belt too loose it will slip and you won't be able to give the engine full throttle. Well, not my engine anyway. The 90 degree twist is too loose. Fiddly belt to set up. If'n I were doing it again I personally wouldn't use an RGM belt clutch because of that stiff slippery AT10 belt. That is just me though and I tend to swim upstream.
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Comstock mentioned in one old post. (if I can find It) You bring it forward till it skips then go back on the gearbox position till it doesn't anymore. You have to deal with the rear chain at the same time. don't forget.
 
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Agree with Schwany. It's not an M8belt which needs to have 90 degrees twist in the top run. The at10 belt slips if it's too loose & it isnt good to run it tight. I fitted a loose keeper plate to My early RGM kit. The clutch was ridiculously light, a thing of beauty. They do strip & make a bird's nest of the wire but its a harsh environment for a rubber belt & we all forget to change the belt occasionally. My race bike snapped the belt at Donnington & the one in my spares kit had been there ten years waiting for its chance. ( planned replacement here would be good! but if it's not broke you tend to leave it alone. If you've got a good complete chain set up, fine but I would never go back.
From memory the front pulley bolts were not metric.​
 
CanukNortonNut said:
Comstock mentioned in one old post. (if I can find It) You bring it forward till it skips then go back on the gearbox position till it doesn't anymore. You have to deal with the rear chain at the same time. don't forget.
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Alrighty

Comstock has also suggested the belt should be loose enough to slip a little when kick starting fully cold, which does not work with an AT10 belt.
Belt can also be adjusted the other way around like Roger's instructions suggest. Tight first then loosened.

Rear chain is slack when I do it. Although pushing down on the chain with one foot can be used to pull the gearbox back in a hurry as long as the adjusters are backed off.

Tire air pressure and chain lubrication and adjustment are the last things I check before taking whatever motorcycle I take for a spin. Always for the last 60 years.
 
Chris said:
Agree with Schwany. It's not an M8belt which needs to have 90 degrees twist in the top run. The at10 belt slips if it's too loose & it isnt good to run it tight. I fitted a loose keeper plate to My early RGM kit. The clutch was ridiculously light, a thing of beauty. They do strip & make a bird's nest of the wire but its a harsh environment for a rubber belt & we all forget to change the belt occasionally. My race bike snapped the belt at Donnington & the one in my spares kit had been there ten years waiting for its chance. ( planned replacement here would be good! but if it's not broke you tend to leave it alone. If you've got a good complete chain set up, fine but I would never go back.
From memory the front pulley bolts were not metric.​
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Thanks Chris. I do have the full stock chain setup in great condition and am just going to go back to that, since for me this is an antique I will rarely ride. The hassles of alignment, too loose/tight, belt aging, etc. just don't seem worth it to me.

In fact, I am surprised by your comment you'd never go back given you had a belt snap on you during a race! Not to mention belt slipping if too loose and not good to run too tight. Sounds like you see the main benefit of better clutch action? Or is it something else, like a noticeable performance boost, not worrying about oil/leaks, gearbox wear, etc.?
 
Im fairly certain that the light clutch action is a function of stack height and cable friction.
With a Venhills cable and proper stack height my stock chain drive setup is a one finger operation.
The RGM belt drive on the 920 is the same.
I do like the belt drive though as it is so light in weight.
Either type drive works for me but right now the belt has the edge. I like the fact that it not only gets a fair bit of weight off the bike but also gets spinning weight off of the trans mainshaft.

One possible advantage with the chain drive is that the Barnett Kevlar plates are running in ATF. They tend to last a very long time when run this way.

The belt drive is running dry and I suspect the clutch friction plates will need to be renewed a bit sooner than with the oil bath chain setup.

Glen

Chain drive clutch on MK3

 
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Hi Doug
I've got a few bikes with stock primary & they are fine, because they were complete & in good nick. The RGM kit we are talking about here came with my Commando project, hardly used because it slipped. I ran a Bob Newby set up on my Rickman 8 valve Bonnie because the Triumph clutch is "carp" & everything in it was knackered. Well, there was no turning back! No stupid pip clutch nuts, heavy springs, knackered tags, loose rollers aah bronze washer! & all that weight lost & no oil in the chain cases.
The RGM kit was an easy sort! I cleaned the plates & ran it without oil, job done. Been on there 20 years. Most of my bikes since then have been belt, unless I had enough stock parts for me to kit them out with a standard primary.
My 960 has a bit of pull & I ride it on the torque, great dobbs of pull, a joy to ride. For the belt to last eleven seasons is amazing. If poor on my part for not changing it. The low weight of a belt drive spinning round is a big bonus.
 
"This bike is mainly an antique/garage art for me as we share the same name. I get my 2 wheel kicks offroad on my KTM 300 dirt bike since I just don't trust distracted drivers here in Texas. "


This makes a strong case for put back the original parts that are on hand, and no cost.
 
Hi, just going to hijack this post as it seems most relevant to my current issue, hope that's OK.

I have had pretty much the exact same failure after a full rebuild. I suspect an adjustment/alignment issue was the problem. However, I also damaged my drive pulley with the wires. As far as I can tell my kit is an early RGM one.

My drive pulley is 28T and clutch pulley is 55T, both 10mm pitch. The drive pulley is 32mm width. The only RGM one that lines up is shown as for racing singles. The new version from RGM that I can see best matches is the "alternator twin" being 27T and 30mm.

RGM Pulley.JPG


Question is, have I assumed correctly and provided I adjust and shim properly. Will this new 30mm pulley work OK with the original clutch pulley (undamaged) I assume this is 32mm also (I will measure later to confirm).

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