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Is it possible to fit an o-ring chain to an A Twin?



greg brillus

Well Known and Active Website User
VOC Member
#2
The chain will most likely hit the swing arm, that's why they used the narrower chain on the twins. Most "O" ring chains are wider than standard so a 520 O ring chain will be as wide as a normal 530. Cheaper to replace it periodically than go to a more expensive type anyway.
 

Robert Watson

Well Known and Active Website User
VOC Member
#3
I put a 520 O ring on mine. Not a big issue for width. I have had rings made from SAE 8620 steel and case hardened .020 deep with a 2.500 bore in 18, 19, 21, and 22T. I can then take an original counter shaft sprocket and re ring the splined hub. Both my A twin and the TTR (and my post war bikes) have been done this way. There are some of these sprockets with a documented 20,000 miles on them. I think I could even put a big fat 530 O ring in there and not touch anything.
 

billirwinnz

Website User
VOC Member
#4
Thanks Greg and Robert.
I used to adjust the 530 standard chain on my Prince every 200 miles and replace it at 4000. I converted to 520 o-ring and have only had to adjust it twice - at 10,000 and 20,000 - so I'm sold on o-ring. For racing obviously there's less drag on a standard chain and mileage is a non-issue.
 

BigEd

Well Known and Active Website User
VOC Member
VOC Forum Moderator
#5
Not really an answer to your question "can I fit an "O" ring chain to an "A" twin" but if you are planning on doing a lot of miles an alternative might be to fit an automatic chain oiler, e.g. Scottoiler.
I use a Scottoiler V system with ordinary engine oil on all my motorcycles. It is actuated by vacuum from the inlet tract and I get 10,000-20,000 miles from a chain on a "B" twin. There are various other auto oiler systems, some electrically operated and some semi-auto and much cheaper, e.g. the Loobman costs £23.00 inc P & P.
One of these systems is likely to be cheaper than new sprockets and an "O" ring chain and easier to fit.
Examples here: https://motoridersuniverse.com/news/1253536-automatic-chain-oilers.html
 

Vincent Brake

Well Known and Active Website User
VOC Member
#6
I put a 520 O ring on mine. Not a big issue for width. I have had rings made from SAE 8620 steel and case hardened .020 deep with a 2.500 bore in 18, 19, 21, and 22T. I can then take an original counter shaft sprocket and re ring the splined hub. Both my A twin and the TTR (and my post war bikes) have been done this way. There are some of these sprockets with a documented 20,000 miles on them. I think I could even put a big fat 530 O ring in there and not touch anything.
Or make the ring up from Toolox 44 at 45HRc just normally workable on a lathe, is it available on the other side of the pond?
 

billirwinnz

Website User
VOC Member
#7
My bike came with a chain oiler from new. They called it a crankcase breather. :)

Oil consumption is a gallon every 1600 miles and I think most of it is through the breathers.
 
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A_HRD

Well Known and Active Website User
VOC Member
#8
Bill, It might sound a bit bizarre, but have you tried putting the bike on the rear stand and fitting an old worn-out length of 530 chain to establish what/where clearance issues you might have? Some rag or maybe rubber wedged to one side - and then the other - against the sprockets will move the chain over each way while you rotate the rear wheel by hand....
Peter B
 

billirwinnz

Website User
VOC Member
#10
Bill, It might sound a bit bizarre, but have you tried putting the bike on the rear stand and fitting an old worn-out length of 530 chain to establish what/where clearance issues you might have? Some rag or maybe rubber wedged to one side - and then the other - against the sprockets will move the chain over each way while you rotate the rear wheel by hand....
Peter B
 

billirwinnz

Website User
VOC Member
#11
Hi Peter
I have to replace the gearbox sprocket anyway so I’ll be able to take a good look at it then. I have samples of several chains. By looking at what I can see of the current 520 chain clearance I think there’s enough for a wider one.
I do know that overall chain width for a given size varies a lot with different suppliers. I forget whose are the narrowest so I’ll have to research it again.
 

Robert Watson

Well Known and Active Website User
VOC Member
#14
IMG_1702.JPG

If the spline on the old sprocket is good, this is not too difficult to do...........
.002 interference and pressed on with the 4 tacks each side.
this is a post war but I have done Burman and even some AMC ones for local guys.
 


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