Britbike forum Forums British Motorcycle specific Brands Bsa bulletin board A65 Primary Chain Tensioner

I bought one off ebay (sold by a Uk m/cycle accessory dealer) at a reasonable price. I suspected it might be made in India but I thought thats no reason not to try it. Yesterday I did try it but it's too long, nearly under the chainwheel.

It was advertised as suitable for A65/50. It would seem it's been made to fit a different bike. Whats your thoughts?

https://i.imgur.com/EC5iWg5.jpg

Looks like for a b44

Did you buy it online and see a photo of it before you bought it?

Ps. There doesn’t look to anything wrong with the existing tensioner.

I saw the ad photo but it was took at an angle, also couldn't remember the shape of the existing one.

I thought mine was badly grooved but when I inspected it it's not bad at all.

Thanks, that's the answer then

Grooved is fine , they cant wear down further than the rollers on the chain ( all thins being equal )

I don't think it's a B44 tensioner as this type has an adjustment bracket that bolts to one of the alternator studs, see first pic below.



The one you have looks more like the second pic which is sold as an A65 tensioner by some shops, its difficult to see if your one is rubber faced or not.




I would suggest trying to fit it and see whether you can get sufficient tension in the chain by tightening the lower adjustment bolt without fouling the chain wheel.

The one you fitted originally looks fine, so you might be better off keeping it.

yes, that's the one.

Incidentally, I noticed that previous owner had put the adjusting bolt in upside down, probably because the insert was lost. Seems like one could be made from hard rubber or plastic? Looks about 1/8" thickness.

The part number for the insert is 68-0249. Autocycle are selling them in packs of 3 for a tenner (inc P&P) on that well known auction site. Your bolt should be relieved hollow to accept the insert on the hexagon. The bottom of the threaded shaft should then have 2 flats for external adjustment. I assume if the PO did what he did, there isn't the external locknut (68-0237) and thread cover cap nut (57-4424). The threads I believe are 7/16" BSF.

I would stick with the old one in the pic ... the geometry of the new part is just plan wrong .

+1

Unless the chain is over tightened (many don’t realise that the chain will tighten when the engine warms up) then the existing rubber will be fine. If it’s too tight then the rollers will stop rolling over the blade and just chew the rubber right off of it.

yes, some more pics here! He might have forgot to put the bolt in before fitting chain as it can't be inserted with chain/clutch assembled!

https://i.imgur.com/2YcU5CP.jpg

https://i.imgur.com/EOUxrw8.jpg

The new one doesnt look like its going to fit, simply too long, I would send it back and get a refund.

Seems odd that there are quite a few suppliers out there now selling this apparently new type of A65 tensioner, at a discount in some cases.

The reason........ less than a tenner a pop.

https://www.ebay.com.au/itm/165442761835?hash=item268528346b:g:QfAAAOSwLEhiWmuG&amdata=enc%3AAQAHAAAA4N%2B6anGkOe3NJ8W0edIn6G8bLQEzoWVmtBqQJYU%2BSyKxnQa5Am0NuBPFgy4oEuAI2QmofgjU%2BDh%2Bthr6r44GvVWInWgsac8rPMz1JOm9HXBLROdtde9xPZwhLjBkPKyhaetfQNMjDdICdj4HbVpQA1LmMsqRsjT%2B4JlQMd3oEIGIvB08QF9eLZcfmJ27X0fhS%2FvyZgrGzlf7%2BxpGKo3txd87w64m%2FHLYOwwLVgJVv0dn%2Bmorm5iHXUNI1ECZGu541FSn6RdMOlTTVY4f4yRg7gYoMstvTw%2FdodKKEk%2BToza4%7Ctkp%3ABFBMpNjNqLZh

Yes, it's going back!. Pity,if it had been correct length, it would be ideal.

Is that where your 10mm socket went?

That's my spare, my normal one is lost/mislaid!

The old tensioner looks barely run in

I realise that now it's been removed, but when I saw one on ebay for £8, I ordered it anyway prior to dismantling clutch.

Basically I want to check the gearbox sprocket, change the oil seal behind the clutch, and check the rotor. Last time I examined the clutch plates they measured as spec., it seems that they have been renewed prior to me getting the bike. Just have to obtain the clutch locking tool and puller.