Fork Oil v Engine Oil

[shammon]

Again i find my fukin forks leaking this time the right side.

I have used original and copiesof fork seal and still after 6-8 weeks they start to leak this being the third time now . Now i have been putting in the correct oil amount and the forks are not pitted or allowing oil past them also i ensure they are fitted correctly, SO i can only asume its the oil? i use the specified one as in the service manual but fork oil is thin or in my view its a lot thinner, than engine oil so can i use engine oil in my forks instead of the fork oil and see if this helps.

Its a Yamaha xj900f 1991 standard fork set up.
any advice cant keep having to strip the bike every 2 months to replace seals.

Andy

[Paddy Blake]

Did you check if the bushes were worn when you had the forks apart.

Paddy.

[T1z3R]

i doubt you can use engine oil, might be too heavy?
why not just try heavier fork oil?
____________________
duck my sick!

[professor]

This exact thing happened on my old bike.
If the forks have been straightened before, for any arbitrary reason, check that they,re not pressed oval. The seals work well to overcome the movement that they need over the oval part for a while, but fail pretty soon.

Also check that the fork stancions aren't worn. It'll take A LOT of miles of riding to get them worn to a point where they'd leak though.

[shammon]

Internal components are ok could be as you say worn or oval, I` expext new ones will hopefully sort it out.

[Walloper]

Fork oil has anti-foaming aditives/properties. Most engine oil does not need this.
Leaks could be due to poor fit of new seals or un-seen rod surface damage.
Strip, evaluate and rebuild.
Make sure you put in the correct amount of oil as too much oil will result in the extra being displaced when the fork compresses/heats up.
____________________
W-ireless A-rtificial L-ifeform L-imited to O-bservation P-eacekeeping and E-fficient R-epair

[stinkwheel]

You can use automatic transmission fluid in your forks.
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[Kickstart]

Hi

If you use heavier oil then you will land up with front suspension that barely moves, having all the shock absorbtion propeties of a concrete runway to a parachutists who equipment has failed.

It needs to be a hydraulic fluid. ATF is suitable for some bikes (recommended in some bikes).

Personal guess would be that the bushes really are worn.

All the best

Keith
____________________
Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing