Topic: are the front forks supposed to have no air inside?

[mazingerzeca]

Hello all.
After rebuilding the forks (honda cb125s), I'm refilling them with fork oil, but after filling them with 140cc there is still air on them. I mean, the spring is not covered totally on oil. Should it be?
Thanks for  your help.

[scunny]

yep, that is common

[CrisPDuk]

There has to be some air in there, or, since fluid is incompressible, the fork won't move.

varying the amount of air/oil and the pressure of the air/gas has a noticeable affect on the fork's performance.

[Really?]

Fluids are compressible but it is negligible.  In this case is does not matter, lol.

I do not know your bike but the springs would not be covered in oil as there should be some sticking out the top for preload.

[crazypj]

Pull the spring out, compress the fork, measure the oil level. usually its going to be in the 4"~6" range (totally irrespective of fork manufacturer or diameter/travel)
 More oil means fork get stiffer in last third of travel as air compresses (the air spring is 'stronger')
 Its useful to know this if you don't have specs
PJ

[Terry in Australia]

You mean I shouldn't have filled my forks right up to the top with fork oil? Damn!!! 

[manjisann]

You mean I shouldn't have filled my forks right up to the top with fork oil? Damn!!! 

Best way I know of to get old fork oil seals out, works slick as can be as long as you remember to remove the circlip.

Brandon