BSA Owners' Club Workshop Discussions

The BSA Workshop => Twins => Topic started by: Captain Mike on 02 Apr, 2021, 08:34

Title: primary chain tensioner
Post by: Captain Mike on 02 Apr, 2021, 08:34
Hi All
I have been adjusting the chain tensioner on my A10 plunger and I have used up all the adjustment to get the chain tension where it needs to be, I measured the thickness of the plate that the chain runs on at 4mm, and I thought this was not very thick and as the chain is approximately 10-15mm away from the outer casing cover, when tightened up, I thought I would look for a replacement, my question is what is the thickness of a new chain tensioner and are there any tricks to getting more meat on the plate that the chain runs on

Thanks
Mike 
Title: Re: primary chain tensioner
Post by: DAVE BRADY on 02 Apr, 2021, 09:04
Good morning Mike,

Running out of adjustment on the chain adjuster suggests that the chain has reached the end of its life.  You could put a thicker plate on the adjuster but that would promote more wear on the teeth on the front sprocket and the clutch.  In my experience timely replacement of the chain means that a few chains can be gone through without the need to replace the more expensive sprocket and clutch basket.  Providing the chain has been kept to the proper adjustment then a new one will fit fine and you will have plenty of scope for adjustment. 

Dave.
Title: Re: primary chain tensioner
Post by: Captain Mike on 02 Apr, 2021, 15:57
Hi Dave

Thanks for that, the bike has been rebuilt before I bought it and I am pretty certain it is a new chain on there, wonder if its too long ? will try to find out what the length is for the chain, previous owner may have fitted the wrong chain maybe, its a 1957 A10 plunger

Thanks for the reply

Mike
Title: Re: primary chain tensioner
Post by: DAVE BRADY on 02 Apr, 2021, 16:36
Hi,

The duplex chain has 80 pitches.  If you do replace it get an endless chain.  Connecting links are OK in the single row chain of the later A10 but a bit of a no-no for the duplex and triplex chains.

Dave.
Title: Re: primary chain tensioner
Post by: Captain Mike on 04 Apr, 2021, 09:10
Hi Dave
thanks form the info I will check this out

Cheers
Mike