motorcycle chain standards

I was looking for dimension information on some motorcycle camshaft drive chains and I found a draft copy of a standards document on various motorcycle chains created for a national standards organization. I've put a copy of that here:

http://www.eurospares.com/graphics/chassis/chainstandard.pdf

It supplied me with a fair bit of information I lacked so I figured there were probably other people who could make use of it too.

cheers,
Michael

Thank you Michael!

+1

Check your PMs Michael

What got me searching for this information was my looking at different bikes that use a 219H cam chain to see if I could find a potential donor of cam sprockets for another project bike. I saw one bike that was 219H originally, but some suppliers were offering an 05 series cam chain and I wanted to know what the difference was. Finding out that the 05 is an 8mm pitch (.009" longer pitch than the 219H) with slightly bigger rollers too, made me wonder about just how interchangeable those chains were.

I enquired about the 219/05 chain issue with a firm that makes adjustable cam sprockets for a bike that originally had 219 and yet sells the 05 chain, and I was told "If you measure the 219H and the BS05 chain, they will measure the same. Both chains fit the sprocket perfectly."

I'm a bit dubious about statement but maybe the 05 with bigger rollers/more pitch rides far enough out to where it works out just right? Running the 05 chain on the 219H sprockets seems to have worked out for decades for a lot of people.

cheers,
Michael

Heh, heh. Given the diabolical shape of most sprocket teeth the larger rollers riding a bit further out might actually work better than the standard.

I've had a few very long lived sprocket / chain assemblies through my hands with teeth slightly shorter than standard having a profile some what involute in shape instead of the usual sharp point. The only factory sprocket of this shape I've ever seen is the engine shaft sprocket on a BSA DB32 / 34 Gold Stars. The most impressive were the pair of final drive sprockets on a T150V Trident I owned which had clearly been made from scratch. Those things eat final drive sprockets and chains, especially my model which was the officially never made conical brake version with the large centre port head 9,000 rpm capable engine, normal 10,000 miles till the sprockets were hooked beyond use and the chain completely worn out. Not on mine. 60,000 miles. Three chains and not a trace of hook on the sprockets. I'm pretty sure it had been warmed over a bit too. Comparing the trajectory of a worn chain entering and leaving normal, matching worn sprockets with that of a worn chain on the Trident made it obvious why. Standard sprockets clearly can't cope with the pitch error of a worn chain. The rollers snag as they enter and leave the tooth gap obviously causing the familiar hook wear. On the Trident even a totally shagged Renold GP chain ran on and off smoothly and quietly with a clean trajectory.

Some fairly pointed enquiries to chain and sprocket makers as to why this shape wasn't the norm got nowhere save for a couple of embarrassed "more than my jobs worth" coughs.

Clive