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Vented Fork Caps


mur
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hi guys a wee question i have been getting a bit of rebound last couple of trials ,moving quickly over rutted ground say,but nothing when lifting in a section ---

the springs are recent and the longer type (happy with them)

oil 15wt newish 180cc

seals fine

everything tightened down.

this bike is trialed every week my question is ----how much oil do i lose (fine mist)through the valves?

more than i thought maybe,have topped up with 25cc more

any thoughts on this ,will know better after sun.

cheers mur ps sherpa

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When I saw video footage of you upside down in that stream last Sunday Mur I didn't consider this fork issue a priority!

There may be lack of fluid in your forks but there was plenty everywhere else apart from the gearbox and primary which probably drained out the breathers into the streams nailing Kelvins prize carp.

Anyway every Bultaco should be treated like that,mine too if I can ever get it running again..

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Mur, shouldn't think you would lose that much oil unless it was upside down.

If you have the vented caps, you can turn the stanchions so the vent holes

are towards the tank and you will be able to track the spray if there is any.

Will try to help if possible. By the way what model do you have?

Regards Larry

Edited by lbhbul
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:D breagh ---are you the all seeing eye of the trials world !!!

i definitely get a fine mist on big compression ---do these vents only breath one way ??

the wee nut inside, below the washer, is not tightened right up, i thought this was to allow the valve to breath ---is that not the case?

larry it is a 199a but a 159 frame 350 sherpa

kind regards mur

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Mur, I don't remember for sure about the tightness, seem to remember when new, they are

bradded slightly and not tightened up so as you thought, to allow them to breathe.

I think but will check later that they work both ways.

Had a chassis upside down not long ago and cleaned up two puddles, had not cleaned the caps,

however not thinking there is any check valve. Will check one later and amend post as needed.

Regards, Larry

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The wee nut is not tightened up because there's a wee spring under the wee washer. It works like a wee one way valve as I stated before.

When my fork cap created a mist at compression, it was because the washer that seals against a rubber, was corroded.

After polishing the washer the mist was gone and everything was clear again ;)

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Mur, for what its worth just took caps off 199. Small nut, down tight; washer; spring; thin washer with I/D to accommodate step and

to cover 4 slots. Regardless of what the spring and washers do, if they don't hiss on compression

the caps are not doing what they are supposed to do. Let them breathe! Some A models have a deflector in the bottom of the

spring to alleviate the oil spray from the dampers.

Regards Larry

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:D thanks again guys ,the washers dont look to bad -------------maybe just got a bee in my bonet about this,seems the caps are working ok and doing their job---

bloody rebound thought!!!! might be technique :rolleyes: !!! thats needed

cheers the noo!!

mur

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Mur, one thing you might try to calm the rebound, I had the same problem with a friend & pursang springs,

was able to make him happy by changing to 30 weight oil in one leg.

Doesn't cost much to try.

Let us know how you get on.

Larry

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well -------------my performance on the bike was mince!!! however little to no rebound a bit firmer fork, but i can live with that.

whenever rebound occurs again i will know to top up!! B)

thanks again for your time guys-- will maybe try heavier oil next time larry.

cheers the noo!!

mur

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