Author Topic: are the front forks supposed to have no air inside?  (Read 1244 times)

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Offline mazingerzeca

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are the front forks supposed to have no air inside?
« on: November 09, 2008, 02:45:36 PM »
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.

Offline scunny

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Re: are the front forks supposed to have no air inside?
« Reply #1 on: November 09, 2008, 02:47:05 PM »
yep, that is common
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Offline CrisPDuk

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Re: are the front forks supposed to have no air inside?
« Reply #2 on: November 09, 2008, 02:48:56 PM »
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.
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Offline Really?

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Re: are the front forks supposed to have no air inside?
« Reply #3 on: November 09, 2008, 04:59:04 PM »
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.
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Offline crazypj

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Re: are the front forks supposed to have no air inside?
« Reply #4 on: November 11, 2008, 08:37:03 PM »
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
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Offline Terry in Australia

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Re: are the front forks supposed to have no air inside?
« Reply #5 on: November 14, 2008, 02:10:30 PM »
You mean I shouldn't have filled my forks right up to the top with fork oil? Damn!!!  ;D
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Offline manjisann

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Re: are the front forks supposed to have no air inside?
« Reply #6 on: December 05, 2008, 01:53:38 PM »
Quote
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.

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