Belt Drive mass

I put an RGM 32mm belt drive on the Commando last week and did some weight measurements to see what the differences are:

Steel Drive Belt Drive

Clutch basket : 2.118 Kg 1.117 Kg

Engine Sprocket : .502 Kg .258 Kg

Chain / Belt : .974 Kg .172 Kg

All up a reduction of 2.04 Kg. That's signicant. I guess the Norvil kit would be very similar and of course no oil either.

Some important reminders - fit the left side tension adjuster, just slacken the top and bottom bolts, set the belt tension to 25mm up and down, use bpatton's method of 2 set squares across the engine pulley and clutch flange butting up the handles to see the out of alignment gap, use the left or right tensioners to close the gap, carefully re-torque the top and bottom bolts, re-check the alignment gap and nip up the tensioner lock nuts. Kick the motor over with the spark plusg out and see if the belt wanders. Then run the motor with the primary open. Refit the left footpeg assembly and go for a 5 to 10Km ride. (wear boots, no laces!) get the drive hot and re-check the up and down tension is at least 20mm. Any scuffing visible on the edge of the belt, then re-check the alignment.

Nice, where are the pics?

Thanks for weighing the items. 4.5 lb off is just about enough to be felt in handling but definitely in response as its spun mass removed, not counting the oil puddle missing. Belts are a tad quieter too. I ain't priced drives in years but assume its about $100 a lb removed. Not bad considering what drilling that much off would cost. Few more oz's lurking in the hunka hunka primary cover, which is heavy side to remove mass off of Cdo's so belts are a smidgen more balanced.

Talking about paying $100 a pound for weight reduction is a joke when you can stop eating cheeseburgers and guzzling beer for a year and lose 10 times that much for free. In fact you SAVE money and can spend it on more new parts!

Trouble is we like eating cheeseburgers and guzzling beer and looking at boobies and riding Nortons. The answer is a little restraint in all except Norton riding :mrgreen:

grandpaul said:

Talking about paying $100 a pound for weight reduction is a joke when you can stop eating cheeseburgers and guzzling beer for a year and lose 10 times that much for free. In fact you SAVE money and can spend it on more new parts!

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Rotating weight reduction is far more valuable that anything else.

Like a lightweight flywheel, the rotating weight reduction could theoretically improve acceleration though it would have no effect on actual max power/top speed. However since the weight reduction involved is NOT on a flywheel/crankshaft but operated through a reduction gear (crank sprocket/clutch basket), I would GUESS (and that's all it is) that the improved acceleration affect would be less then if the weight reduction was applied directly to the rotating mass of the crankshaft assembly.

But, as noted, lighter is usually better (assuming sufficient strength is present). OTOH, I don't personally see a cost/benefit to a belt drive conversion but that's just me; I realize a lot of people like them.

In long term practical sane timid to highly illegal wild operation there is no good reason to fit a belt. I had it both ways and only find belt noticed if in competition or hauling bike out a ditch into a truck. Everything said about belt benefits are so but so what - its not that much better to stress over it at all. If money to burn then for sure its a good upgrade, but I ain't bothering to on my good ole Trixie Combat with most the warts of factory issue to add to the quaint character and road wits testing to get home now and then on our own power.

mike996 said:

OTOH, I don't personally see a cost/benefit to a belt drive conversion but that's just me; I realize a lot of people like them.

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Surprisingly, the 32mm belt drive conversion is actually 30 Pounds Stirling (around US$47) cheaper than buying the equivalent parts in triplex chain version. On the other hand, the chain sprockets rarely wear out, but if you've got a rusty basket case rebuild it makes sense to go to belt.