Belt drive do or don't?

steven wardlaw · Jan 1, 2009

O'kay all you gaer heads out there i need help on one upgrade that might have already been covered. I'm about to pull the primary to get the front sprocket off to do the 520 chain conversion. While I have this torn down I was also thinking about the belt drive primary swap. Please help me make up my mind on this swap over. What has to be done to keep the belt dry (oil leaking in from sump and trans)? What is the best kit to buy?

grandpaul · Jan 1, 2009

Personally, I like the OEM chain setup just fine. It's never bothered me one bit as long as it's properly adjusted and maintained.

cash · Jan 1, 2009

I've had a RGM belt fitted to my Mk3 for 14 years it's got to have done 30K plus. The belt is starting to wear a little as the clutch is starting to rattle. Was it worth it? I don't think so, would I go back to a chain? no.

I would go for the Haywood or RGM system as they use the best belt you can buy, and you can run it wet or dry.
Cash

tpeever · Jan 1, 2009

I'm with grandpaul on this one. I don't see any reason to switch over to a very expensive belt drive system for an antique street bike. If your chain primary is already worn out and needs replacing or if you have unlimited $$$$ or you want to race and think the extra weight savings is worth it, then switching might make sense. That said, I don't have any experience riding a Commando with a belt so have nothing to compare to and can't comment on possible advantages in terms of smoother power delivery, noise reduction etc. I may also be one of the lucky few Commando owners who has a primary that doesn't leak which may also be why I see no need to switch!!

Dr_Hiller · Jan 1, 2009

I'm in the belt drive camp. Quiet, light, efficient and not terribly expensive for those with gainful employment.

I use the old iron clutch basket as industrial art now - and it seems infinitely better suited in that role.

Chris · Jan 1, 2009

belts

Hi
I run RGM on 2 street bikes, 1 Norvil on the race bike(750 Caffrey) 1 Bob Newby on the race bike (Dresda Dommi) 1NEB going on the next project.
If you are building from scratch I dont think the cost is a major factor.
Saying that I have managed to buy 3 kits from other people for very little as they were not happy with them. Lots run fibre plates in oil & then complain about the slipping clutch & the other problem seems to be deck height & running the correct thickness outer plate. Les Emery let me into that little nugget.
I have a 750 Commando with standard chain set up that has been on the bike since new. I started using belt drive as my Triumph 8 valve 686 race bike constantly leaked from the primary cover. When the clutch was worn out. I took the chance to get rid of the horrible rollers pip nuts & thrust washer, for a sealed bearing & dry primary. The difference on my Triumph was huge. Smoother dry very easy to adjust & quick to strip.
The Commando has never been as bad in any of those areas so unless it needs replacing!
Me I just like the weight saving.
hris

geo46er · Jan 1, 2009

Belt Drive

Greetings Steven,
Regarding the belt primary: weight saving = yes, eliminates one potential source of oil leak = yes, less vibration = theoretically, easier and better clutch action = absolutely, expensive = wife and kids don't really have to eat three times a day (just kidding), not too bad, approximately $400usd from www.clubmanracing.com If you are worried about oil getting on it, install a new crank seal and one of Dave Comeau's clutch rod seals while you are at it.

GB

ntst8 · Jan 1, 2009

I have an RGM belt drive, have had no issues but can't say i noticed any great improvement once it was fitted.
They are much more sensitive to set up than the chains, if not set up properly the belt will chew out in no time, whereas it is pretty hard to destroy a chain.
The major advantage i find is if you have the primary cover off with any frequency then it saves the minor bother of draining and refilling the chain case.
On a road bike i would rate it nice to have at best, but well down the spending list.

Coco · Jan 2, 2009

cash said:
I've had a RGM belt fitted to my Mk3 for 14 years it's got to have done 30K plus. The belt is starting to wear a little as the clutch is starting to rattle. Was it worth it? I don't think so, would I go back to a chain? no.

I would go for the Haywood or RGM system as they use the best belt you can buy, and you can run it wet or dry.
Cash

Do you use the e-start frequently?

cash · Jan 3, 2009

Coco wrote:

Do you use the e-start frequently?

The starter can't be fitted on this early RGM belt drive. May have to fit one sooner than later

Cash

steven wardlaw · Jan 4, 2009

Thanks for all the imfo. After reading these post I will probably stay with the chain. I'm always looking for some way to improve my bike but i can honestly say that the chain has never given any problems. I did go ahead today and pulled the spckets off to cut down for the 520 x ring chain. Thanks everybody for your help!

bigstu · Jan 5, 2009

belt drives

I installed an RGM Motors belt drive system on my 850 Mk11a. It uses the polyurethane belt which is more resistant to slight oil contamination and has better torque capacity.
The alignment between engine and gearbox is more important with a belt drive and really should be installed with a double sided adjuster for the gearbox, allowing one to throw the alignment.
This is imprortant as the clutch shaft is bent and pulled towards the enging during hard accelleration.
The big advantage of a belt drive that nobody has mentioned (suprisingly) is that one can run the clutch DRY. This means you can buy a new set of 'sureflex' clutch plates and have a slip/drag free superlight clutch in a leak free enclosure.
In order to stop oil wicking along the clutch pushrod you need to get a special clutch basket nut with a built in seal to ovoid the clutch plates being splattered with 80 weight gearbox oil.
There should be no need to stop oil coming from the engine, but I wouldn't garrantee this.
If you make all of these upgrades, along with a 'featherlight' teflon lined clutch cable, you will have a very expensive but wonderfull clutch/primary drive system.

Reggie · Jan 5, 2009

Good point bigstu.

I have fitted a belt drive and an oil seal for the gearbox mainshaft with fibre clutch plates, and it is a delight to have a Norton which does not slip it's clutch at all, not even after quite a bit of usage, and with appropriate clutch packing, gives me a very light clutch.

I had a bit of oil leakage past the main bearing oil seal on the seals shoulders and used silicone gasket goo to seal this, although you can get an oil seal (from steve Maney and probably bearing shops generally)which has rubberised shoulders that should go a long way to making this seal 100% effective. That's what I will fit the next time I come to replace the main bearing oil seal.

JimC · Jan 5, 2009

If you are having problems with crankshaft seals and have a 72 or newer Commando, install the Yamaha XS 650 PCV valve and be done with it. You can change seals until you are dizzy, but you'll still have a leaker. The problem is not the seal, it's the pressure in the crankcase. http://www.mikesxs.net/mikesxs-fuel_system.php?category_id=4.7

Skoti · Jan 5, 2009

Hi JimC,

PCV valve sounds like a good idea, but what happens if you have a commando that wet sumps a bit?

When I start my commando after parked up a few weeks some oil is forced up through the crank breather pipe back to the oil tank, how would your XS650 PCV breather handle that? :?

cash · Jan 5, 2009

Skoti,

Yes! 8)
Cash

JimC · Jan 5, 2009

When I start my commando after parked up a few weeks some oil is forced up through the crank breather pipe back to the oil tank, how would your XS650 PCV breather handle that?

Skoti,

Just fine!

If you think new seals will take care of the problem, go ahead. I'm only telling you what I learned from prior experience. The Yamaha PCV valve is essentially a one way valve. Any oil that goes from the engine to the oil tank thru the breather hose will not be affected. If you have a wet sumper it's generally best to drain the sump before you start the engine. If you have a crankcase full of oil and the pistons try to compress it (downstroke), it will go somewhere. That's asking a lot of a seal, any seal.

Skoti · Jan 5, 2009

Hi Jim,

I don't dispute your advice, just wondered if the PCV valve would cope with oil being pumped back up through it due to wet sumping.
As you say it works fine, maybe I'll give it a go.

Pictures posted elsewhere on this site look really tidy with this XS650 PCV plumbed in and bolted up to the rear of the air filter bracket housing on a MK2.

JimC · Jan 5, 2009

Skoti,

That's probably mine.

Never mind me today. I'm having one of those days from hell. Sorry if I was abrupt.

BillT · Jan 5, 2009

Skoti said:
Hi JimC,

PCV valve sounds like a good idea, but what happens if you have a commando that wet sumps a bit?

When I start my commando after parked up a few weeks some oil is forced up through the crank breather pipe back to the oil tank, how would your XS650 PCV breather handle that? :?

If it wet sumps that much, might it be worthwhile to drain the crankcase and pour it back into the tank?

Belt drive do or don't?

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