Primary Chain

[PGX11]

Hello Chaps
The bike is a 1952 18s (tin chain case).
We're currently in Winter Maintenance mode with the outer chain case removed.
I've done over 20,000 miles with the current primary chain. Is it time to replace it with a new one?
How long do they normally last if kept well lubricated?
What's the best way to check for wear please?
Thank you for your attention
Chris Moreton

[billbeavis]

Hello Chris,
There used to be good advice on Sprockets Unlimited about chains but since John died, Jane hasn't been able to continue the business so no web site. Maybe advice is available elsewhere. However, my current chain has been on for 24000 miles and I think will be ok for a while. I left the previous one on for too long and don't know how many miles it had done but realised I had adjusted it so much the top mount bolt was very near the rear of the engine plate slot. With the chain on now the top bolt is still at the front of the slot.
If you have the cover off you can give the chain a good inspection and also the sprockets for wear and hooking.
I remember reading that chains don't stretch - they wear at the pins and so seem to get longer. There is a rule for each chain link size as to how much longer in length they can go before needing replacement. That info used to be on Sprockets Unlimited.
Bill

[billbeavis]

Hello Chris,
I must correct my earlier answer. I had a look way back through my records.
The primary chain the bike has now with the top mount bolt forward in the adjustment slot has done 8400 miles. The previous chain I changed at 16000 miles. The one that caught me out (it broke - fortunately without any further damage) had done 28000 miles. Since that happened I used to look at other bikes like my 350 to see where the top bolt was in the slot. All seemed to be forward and that just re-enforced my view that I had let my adjustment on the one that had done 28000 miles get too much.
I seem to get much better miles out of a rear chain (53000, 69000) hopefully due to my lubrication regime. My speedo is now on 144500 miles.
Bill

[PGX11]

Hi Bill
Thanks for your kindly advice. Time for a new one then - better safe than sorry eh!
All the best
Chris

[PGX11]

PS. Congratulations on your 144,500 miles!

[jmbradford]

Also have a look at the inside of the side plates , they are often worn more than you expect particularly if the clutch drive shaft is bent....like mine.
John B.