Can I run an open primary with the stock chain?

Hello, a question for those who know more than me (most people). I'm in the middle of some off season work on my 850, and am finally going to be fitting rearsets! I decided to go with a set of Tarozzi's. Since they don't make a kit for the Commando I will be custom making the mounts. The main obstacle that I see so far is spacing the left peg/lever assembly out far enough to clear the primary cover. I have always loved the purposeful, mechanical look of the sheet metal style primary guards run on many race bikes, and plan to fit something like this to my bike eventually. This would also have the benefit of allowing the left peg/lever to be mounted much further inboard than is possible with the bulky stock cover. Of course most of these bikes also run belt drives and most seem to omit the stator. I plan to fit a belt at some point, but need to spread out my parts investments a little bit. So my question. Would the stock triplex chain and charging system be safe to run in a unsealed primary for a season? Of course I would take care to keep the chain clean and lubed, and fit a clutch pushrod seal and sealed bearing. The reason I would like to do this now is so I can mount the rearsets in the position I want them once, and be done with it. Thanks for any input, Gabe.

my guess is the majority of people on this forum would say no

the primary chain is very different from the single row final drive, the primary is triplex and so three times the links and sprockets

a sealed primary also throws lube on the alternator rotor and stator removing heat

I would say no, based on my experience with trying it. Back in the '70s I was racing a Commando Production Racer at Laguna Seca, when the primary outer cover broke (long story) and wouldn't hold oil at all. Unable to fix it in time for the race, I loaded the triplex chain up with chain lube and went out for practice. Before the end of practice, the chain broke, jammed up between sprocket and inner primary cover and destroyed the cover.

For another example, although not a triplex, I have a friend who races a Rickman Norton with a single row primary chain, a la Atlas, and has had no problems since he switched to an 0-ring chain. Prior to that, he used a conventional chain, and had trouble with it lasting to the end of a single race meet.

I think you would be guaranteeing a failure by trying to run the triplex without oil in the primary.

Ken

I have often thought about the same thing. Does anyone make an O ring triplex chain?

Dig up the 450 bucks or so to get a belt drive kit and don't look back.

You could do more damage than that with a broken triplex chain.

Russ

Thank guys! It is great to have a resource like this forum where I can find someone like Icrken with first hand experience in only a few hours. I thought that might be the case from looking at the triplex chain. Pretty light compared to a final drive chain. I guess I will either pony up for a belt or just plan on reworking the rearset mount when needed. How about the stator? sounds like it may need oil for cooling? Although I would think there are lots of guys running belts dry in the stock primary?

Lot's of belt drives out there, many with no venting. Heat doesn't seem to be a problem with the stators.

Russ

Every belt and drive manufacturer and vendor and famous builders and mean heated testers know sealed and dry is actually better in the long run as hard as you can burn fuel and spin up and load charger. Venting or going w/o a cover removes some more mass and is rather decorative plus the 7 oz of lube gone too so its very common benefit to see in cycle that never leave civilization in nice weather.


Commando Fiberglass Outer Primary Cover (1969-74) - With Norton belt drives eliminating the oil from the primary drive, it has become increasingly popular to machine a �hole pattern� in the outer cover to both vent the belt and more importantly add a custom look to the bike. To eliminate both the need to modify the factory cover and to work around the existing inspection holes/caps, we have had a heavy duty, outer fiberglass cover produced. The standard inspection/access and oil level holes have been eliminated while the factory mounting system has been retained. The cover is currently available with a gloss black gel coat finished . - #C3093 - Temp out of stock.

I was running a belt drive for a few years and the last few months it kept trying to run off the front pully, I also had two gearbox adjusters but still had troubles getting it to run straight,I was running a open inner case, behine the clutch housing was completely open (it was damaged by a thrown rear chain so I cut the damage housing open) and vents at the front of the inner case, after damaging a few belt I decided to go back to chain (never had any problems with the Triplex chain) but I like running my clutch dry so I put the chain back on still with the open inner case and spray the chain with chain lub as the chain is exposed at the clutch housing.

Great idea at the time but found the chain would only get about 50 miles and needed to be lubbed again even putting on thicker oil was no good it just flick off quickly and made a big mess all over the bike so after about 500 miles found out it didn't work, I was lucky I had a replacement inner case and had to go and pull the primary apart again to run oil in the primary, the chain needs oils spashing around it at all times to stay lubbed so now run tranny oil in it and have had no more problems and so far the clutch is not slipping, I am using early Fords tranny oil seems to be good on clutch plates.

Ashley

I run single row heavy duty KH428 primary chain with Jawa engine sprockets and manx clutch. The engine sprocket is usually as large diameter as possible so the chain bend around it is less severe. In the old days I would have used the oil drip off the Seeley frame to lubricate it. Using the spray can, you can get a full race meeting plus a practice day quite easily. If you use the belt drive you immediately lose one gearing option, and have to change either the gearbox sprocket or the rear sprocket, if you have a problem at different circuits. The Jawa sprocket is on a spline, so you undo one nut, and muck around adjusting the chains. On a TTI gearbox the gearbox sprocket holding nut is done up to 80 ft lbs. I wouldn't run my bike at a large circuit with that setup.

From memory I think the standard triple row engine sprocket on the commando has about 22 teeth. I was recently using a 21 tooth single row sprocket, which I think was larger dia. due to the different pitch. I've now moved to a 23 tooth single row sprocket because I believe by using that the chain gets an easier time, and the engine has less purchase on the gearbox mainshaft. For some time I've been interested in the new Katana engined XR69 Replicas our historic guys are developing. Normally the Katana engine has 5 speeds - the XR69 that Crosby rode in Europe had a 6 speed close box. I was talking to a father and son at Winton a few weeks ago about their racing car and the bike they had there . The car has a 1400cc Suzuki Bandit engine in it with a 5 speed box. The bike is the GSXR750J Suzuki with the 6 speed close box. The father had fitted one of the 6 speed close boxes to his 1400cc race car. He said it was much better to drive however he shattered a gear and completely destroyed the box - begs the question about the primary gear ratios ?
In my gearbox on the Seeley , I tend to try to shift the loads to the secondary by spinning it faster.

I was running a belt drive for a few years and the last few months it kept trying to run off the front pully, I also had two gearbox adjusters but still had troubles getting it to run straight,

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Yep sir that's what taught me the hard way about sleeve bushes' lack of lube when ruining dynamics of lower gear travel and straffing. As long as Basket stable belt stays put, then nothing for it but re-do the AMC box again or treat the symptom with Triplex chain and teeth and oil bath which is much more tolerant of basket wobbles. Andy Chain Man had a solution in single or double row for some other brand primary ya might search up.