Belt Drive benefits

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Dec 30, 2003
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A lot of the "modifications" for Commandos while popular don't appear to me to have significant benefits for normal road use especially when weighing cost and hassle to benefit. Looking at belt drives, those of you that have converted and have run for a while, what's your long term honest opinion.
I converted my primary to belt ten years ago.
I flat love it!
The primary runs DRY, so no leaks, and blessedly DRY clutch plates, truly no maintenance.
The belt is much lighter than a triplex chain so the primary feels smoother and lighter, and I feel the gearbox shifts lighter.
I would not go back to a chain primary.
Yes it is a pricey conversion, and you do have to purchases or make up a left side threaded gearbox adjuster to ensure the belt runs true.
I have two pictures of my left side threaded adjuster in the FILES sections of the INOA online Norton forum to view.
I remove all three primary cover inspection covers to vent the primary, other don't and say no necessary.
The belt baskets and the engine plates get hot and expand so the belt is set up with significant slack when cold.
Hope this all helps!
Personally less vibration/mechanical noise and running a dry clutch. Best to fit a double sided primary chain/belt tensioner with it.
There are a number of things I did with this bike (rear disk, left shift conversion) that I wouldn't do again. The belt drive isn't one of those. Quiet, clean, efficient - that's been my experience.

If one has to replace a bunch of stuff in the primary, I'd vote for the conversion. But, if everything's buttoned up nicely and working fine - I'd wait.
Three mods I've done on my Combat that I would recommend:
1. primary belt drive
2. front brake , which consists of a11mm master cylinder, floating 11" disc, a 2 piston caliper with a stainless steel brake line
3. Yamaha XS PCV valve

One I would not recommend is a Boyer ignition. It has some design flaws. There are better electronic ignitions on the market.
I certainly wouldn't put a belt drive conversion on the list of essential modifications.
A lot of people seem to do it because it lets you run a dry clutch, but there are cheaper well documented ways to stop the clutch slipping if that's the problem.

If you've got the money and like to play, go for it ,but it doesn't really add to rideability or reliability.
Its a bit smoother-maybe and a bit lighter but for road use I don't think it really makes sense.
The best argument for a belt is that if you're using a suitably lighter clutch, there must be a considerable reduction in loading on the gearbox components.

It's also possible to raise the gearing and speed up the box which helps and which is not possible with a chain as no-one makes alternative triplex sprockets.

I don't have one in my 850 as I've been put off by seeing too many people pulling shredded belts out of bikes that have been trailered back to rally sites. I've never seen that with a primary chain. I realise of course that poor assembly is often to blame but some of the most popular kits have had rather suspect location of the bearing in the alloy clutch drums.
All of the above benefits with a LARGE weight saving, which can only be a good thing, but I really love the smoothness on the over run. When you back off it is so much smoother than a chain. Set and forget. I've taken the teeth off one belt but I'm sure now it was an adjustment issue. The new one is doing fine.
I suspect the few belt failures I am aware of were probably also caused by owner fitment. I looked at one and the belt was the least of that bike's problems, it was maybe just the one to save the owner's life by failing. Such a waste of many expensive parts on that bike....
Thanks everyone for the input. Believe I'll follow Dr Hiller's recommendation. My chain driven primary is doing just fine for now and I'm going to spend my money this winter on gearbox bushes and hopefully not gears.
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