Greetings from the sunshine state...

Pacho said:

Not sure why he went with a belt dive. My feeling is to go back to a chain and oil be dammed.

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Belt drive has a number of advantages:

No oil needed in primary case = no possibility of leaks from that area, and no need to regularly check/ top up.

Dry clutch plates have much higher torque capacity, so the spring pressure can be greatly reduced without causing slippage. This results in less stress on the fingers, the cable and the actuating mechanism. With the diaphragm spring, this is done by INCREASING the stack height.

Some belt drive kits offer a range of other ratios as well as the standard ratio. This is something you might want to check on your bike. Also, check if your brother fitted an oil seal to the clutch rod.
A higher (numerically lower) ratio is preferable IMO, because it gives higher overall gearing without the added stress on the mainshaft that a larger sprocket causes.
Another benefit is that kickstart effort is also reduced.

Why do you want to go back to a chain?

Additionally, the clutch pack in a stock primary is very heavy. So assuming that the belt drive has an alloy clutch housing, it is the first step in reducing some of that weight.

Pacho,
The Belt drive is a far lighter system than the chain drive. Your clutch basket is alloy and your crank drive hub where the chain system is steel. The belt is far lighter than a chain. Going belt is +++ in my books. A good mod. Its easier on your gearbox as well.
Cheers
Thomas

rvich said:

That light green thing sitting in the way looks like an Austin Healey. I'll tow it out of there for you if you

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Good eye Rvich! 56’ bn2 100-4 original paint .

https://www.accessnorton.com/NortonCommando/primary-chain-death.23993/#post-354360

texasSlick said:

Best to buy chains from Andy the Chainman, or from industrial suppliers who provide chains with all the appropriate US and Euro certifications. Never tell the counterman, the chain (or bearing) is for a MC, they will often refuse to sell it to you. My standard answer is "it is for an air compressor."

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https://www.accessnorton.com/NortonCommando/primary-chain-death.23993/#post-354274

andychain said:

It is known, to those in the know, that the vast majority of triplex chains available are crap, please note the term majority. Laverda owners found this out years ago and in vast numbers changed to a duplex chain from a Mercedes diesel motor, that was 17 years ago. I sold many chains, into the thousands of pounds and have sold few since, with many of them fitted to race engines and high mileage road bikes. A few years ago on this forum I offered the same product to Commado owners with very limited take up. Just google The Chain man and talk to me, I will tell you the advantages. Also those who have taken the chain please give me some feedback. Virtually every belt drive drive on any bike gives issues although people spending many hundreds of pounds tend not to admit it, and Harley owners are changing back to chains.

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https://www.accessnorton.com/NortonCommando/primary-chain-death.23993/#post-354348

andychain said:

Even iwis who I believe make the best product has a plant in China for its Elite brand and I will not sell it. When iwis bows to industry pressure and produces only budget product that is the time I stop selling chain.

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https://www.accessnorton.com/NortonCommando/the-chain-man.24273/

there are also a claim or 2 of successfully sealing the primary covers, i'd have to dig for those details, but tons of 'drip drip' stories out there,

along with stock clutches intended to run dry, slipping

https://www.accessnorton.com/NortonCommando/primary-belt-drive-pros-and-cons.10001/