79 special, fork oil capacity

[Far Canal]

Hopefully I will be able to have a crack at changing my fork seals in the next day or so. Think I had read somewhere that the correct amount of oil to use is 225cc in each leg/slider. Could someone please confirm this as I am not 100% certain.
225 cc does not sound like much oil.
I had heard that a "rule of thumb" with fork oil in general was to have front end off the ground.Take out springs, push sliders all the way up,then pour in oil till its 120mm from top of fork tube.
Will be interesting to see how this theory compares to 225cc or whatever its meant to be specification.

[bikerphil]

The capacity for 225cc fork oil for the 79 Special is correct. You will find the measurement from the top of tube with fork collapsed will be much greater than 120mm, the oil level needs to be lower on these air assist forks. If you change your springs and/or use no air assist, you can go ahead and use a bit more oil to lessen dive upon braking. JMHO

[Far Canal]

Thanks Bikerphil.In your humble opinion do you think the air assisted side of things ever worked? I have read (maybe I read too much) that the whole air assisted thing was a 70's 80's thing that was bluntly "a failure"
Asking fork seals to keep in oil is one thing. Asking them to keep in air under pressure is another. I happen to live in a place where there is 6klm of near motocross bitumen till I hit the main road and go through fork seals like beer!
Well maybe not beer, electricity bills perhaps.

[jjz28]

my air works fine. I just done my seals and used 7.5 oz which is the same amount as you stated. The air makes the front a little stiffer, I like it. I used hydraulic oil in mine cause it was cheaper.

[bikerphil]

Thanks Bikerphil.In your humble opinion do you think the air assisted side of things ever worked? I have read (maybe I read too much) that the whole air assisted thing was a 70's 80's thing that was bluntly "a failure"
Asking fork seals to keep in oil is one thing. Asking them to keep in air under pressure is another. I happen to live in a place where there is 6klm of near motocross bitumen till I hit the main road and go through fork seals like beer!
Well maybe not beer, electricity bills perhaps.

Yes, the air assist works fine but IMHO, it is a hassle to check the pressure every so often, and yes it was a 70-80's thing. Very few bikes with the exception of touring models use air assist anymore. Your best bet IMHO is to upgrade your springs and there won't be any need for air assist.

[jetmechmarty]

Yes, the air assist works fine but IMHO, it is a hassle to check the pressure every so often, and yes it was a 70-80's thing. Very few bikes with the exception of touring models use air assist anymore. Your best bet IMHO is to upgrade your springs and there won't be any need for air assist.

What he said! +1