Has any one tried 0w-30 grade oil in the forks, my A65 has had new fork legs bushes and seals, still on the same springs, i currently have 20w50 castrol in them as was advised it would stop the problem, they do not bottom out all the time just the odd ocassion, maybe the springs have seen better days and need replacing. ive ordered some 0w-30 to try first, but in the back of my mind i think the springs could be the problem. any advise always wecome, except lose some weight you fat bar steward lol.
If the forks are bottoming out, then using a lighter oil won't help that. It will make it worse.
Instead of using an engine oil, why don't you use a dedicated fork oil? I don't have any problems with Rock oil 20wt in my 68 Lightning (or other forms of a similar design)
You could also try SRM progressive fork springs. I find these are a real advantage too.
You could make some nylon bush spacers to go top side of the springs for some pre-load, you wouldn't need much, no more than half an inch otherwise you can get excessive "topping" out. At half inch I was still getting some topping out, but back when I tried that I was 2 stone lighter than I am now.
If you don't have the later dampening additions to the forks (your bike is fitted with pre 66/67 forks) then you could try the Eddie Dow type damper rods again this will help.
Are they bottoming out or topping out?
I get a thud on some holes in the road. so not sure.
Its more common for bsa forks to top out.
Ive ordered some springs from srm so will fit those and see how they are. i wil come back with results as soon as i get them fitted and tested.
Quote from: cdsdorset on 04 Jul, 2023, 09:26
Its more common for bsa forks to top out.
forgive my ignorance top out, i assume that means they bang when full extended quickly.
Gob smacked with the service of SRM, springs turned up at 11 am today, i only ordered them yesterday at 3pm. I fitted them and tested it, no more banging. mine must have been shot, because the new ones where 1 1/2 longer than the one i took out. i left the oil in and shelved the 0-30. thanks for the replies.
Great news!
I do like mine with the progressive springs. As well as the srm springs on my pre oif Lightning, I have the IKON progressive springs on my OIF forks. They are great in my opinion and you can tell the difference when you ride a bike that doesn't have them.
Enjoy your ride.
The Forks banging on the return is more due to oil level than grade. The way they work is at the end between the top bush and bottom bush, there is the loose nylon sleeve and on the stanchions there ore two tiny oil transfer holes. As the fork stanchions approach the top of the slider the oil is sloshing past out of the way and at the very end the nylon sleeve restricts the space and the tiny holes slow the flow further creating a 'last minute' damping effect.
If the oil is too low, it will have all returned to the bottom before this point leaving no oil to squeeze through and slow down the travel.
I've had A65's for donkeys years and it was only last year I worked out how this all worked.