Ariel Owners Motorcycle Club

My OG 250 parts book says the primary chain should be 1/2 x 0.305 which I believe equates to a 428 chain. However, when I went to fit a 428 chain to the chainwheel it began to pick up after a few links and was slightly riding up the sprocket teeth when just over half way round. on the front sprocket it seems to fit well. Is a 428 chain correct or should I be looking for something else?

Any advice gratefully appreciated.

By the way, if anyone has a petrol tank, oil tank or chaincases for a 1939/40 OG250 I'll be happy to hear from you....

hi have you got the old primary chain and does that fit OK, then i think you may have the wrong pitch chain

Guy
As far as I'm aware 1/2X.305 is as per this link (check the comprehensive set of dimensions on the 'Technical' tab)
https://simplybearings.co.uk/shop/p2003 ... _info.html

Looks pretty similar to what '428' chain is dimensionally - so have you got a duff sprocket?

SG

Is it binding on the side links or the rollers? There's different diameters for US and IMP chain. Nev

Thanks all, I'll check the chainwheel again but unfortunately the bike came in boxes of bits and no primary chain. Having had another look at it, it seems to be binding on the rollers and riding up the teeth as if the rollers are a tad too large diameter.

It's the roller diameter that varies. Stick to a good motorcycle chain not industrial ones. Don't use split rollers either. They end up in the bottom of the chaincase. Nev