Is it possible to change fork oil without doing the seals if they arent leaking?
What weight oil do people recommend?
Fork oil
Re: Fork oil
yes, use a front paddock stand to rise the front, remove front wheel, brakes, etc then remove the fork leg (one at a time to maintain yoke alignment), remove the top of the fork remove spring/spacers etc and pour out the oil, pumping the fork leg helps get it all out, then refit the and repeat process on the other leg. Once the two legs are drained and re-fitted, install the springs and add the oil, making sure you maintain the correct air gap (easier said than done) see below.
The above is how I’ve done it in the past but there is a small allen bolt at the bottom of the fork leg (accessible when the front axle is removed) this bolt retains the fork internals, but I’m pretty sure removing it would result in all the fork oil running out, so it may be this is way to drain the oil without removing the forks from the bike, maybe someone who as done it this way could shed some light on it.
As for oil when I fitted my fork springs I used 7.5 wt oil, but initially found it to had, so I changed it to 5 wt but now it’s to soft so I’m going back to 7.5 Wt which I think is probably the best compromise, although the air gap is equally important and needs to be set correctly and I have to admit to not really knowing what I’m doing re air gaps, I understand the principle but I don't think I'm getting it right, firstly I need something to measure them accurately, at the mo I’m trying to get the same amount of oil in each then use a steel rule to check the gap, this isn’t ideal and I’m sure there’s a better way, any suggestions welcome.
The above is how I’ve done it in the past but there is a small allen bolt at the bottom of the fork leg (accessible when the front axle is removed) this bolt retains the fork internals, but I’m pretty sure removing it would result in all the fork oil running out, so it may be this is way to drain the oil without removing the forks from the bike, maybe someone who as done it this way could shed some light on it.
As for oil when I fitted my fork springs I used 7.5 wt oil, but initially found it to had, so I changed it to 5 wt but now it’s to soft so I’m going back to 7.5 Wt which I think is probably the best compromise, although the air gap is equally important and needs to be set correctly and I have to admit to not really knowing what I’m doing re air gaps, I understand the principle but I don't think I'm getting it right, firstly I need something to measure them accurately, at the mo I’m trying to get the same amount of oil in each then use a steel rule to check the gap, this isn’t ideal and I’m sure there’s a better way, any suggestions welcome.
Last edited by budd on Mon Sep 12, 2011 6:08 pm, edited 1 time in total.
I've now gone all European and bought a KTM Superduke GT and Aprilia RSV1000R 
,
Storm is now gone
. .
, Storm is now gone
. .
Re: Fork oil
Same as what budd said, take them out and tip them upside down, then pump them. No need to change seals or anything else. if the contents are really dirty, it can be worth flushing them through with some white spirits, making sure to leave to drain.
7.5 wt [note that it is ok to mix 5 and 10 to make 7.5]
Air gap should be 145mm from the top of the leg to the oil, but this measure is with the spring out and the fork fully compressed. using a syringe with a hose cut to the airgap length allows you to slightly over fill then remove till correct setting.
7.5 wt [note that it is ok to mix 5 and 10 to make 7.5]
Air gap should be 145mm from the top of the leg to the oil, but this measure is with the spring out and the fork fully compressed. using a syringe with a hose cut to the airgap length allows you to slightly over fill then remove till correct setting.
AMcQ
Re: Fork oil
7.5 wt [note that it is ok to mix 5 and 10 to make 7.5]
How does this work then, my calculator tells me 5 and 10 make 15 ?
How does this work then, my calculator tells me 5 and 10 make 15 ?
98% of all Harleys ever sold are still on the road. The other 2% made it home 
Re: Fork oil
alec wrote:7.5 wt [note that it is ok to mix 5 and 10 to make 7.5]
How does this work then, my calculator tells me 5 and 10 make 15 ?
The 5 is thinner [less viscous, more runny] than the 10, and when you add that to a thicker oil [the 10 wt] it dilutes the 10, so if you mix 50:50 it will be 7.5...........trust m
e I am a doctorAMcQ
Re: Fork oil
The bottom allen head bolt hold the damper assembly in position and has to be oil and pressure tight. Only remove it if you need to split the bottom/top legs to change oil seals. (Although I could not split my leg this way as there was not enough clearance to allow the bushings to come free. I suspect that a PO has rammed a washer in the seal well.). Its usually in tight enough to need a rattle gun to shift it, an ordinary allen key runs the risk of rounding the bolt head. A simple and cheap drain plug would make the job so easy.... cost accountants at work again.
Re: Fork oil
IIRC mine had a copper washer sealing the allen bolt, and your quite right they are tight I used a 3/8 drive snap-on allen 'socket' on a 1/2 breaker barjdugen wrote:The bottom allen head bolt hold the damper assembly in position and has to be oil and pressure tight. Only remove it if you need to split the bottom/top legs to change oil seals. (Although I could not split my leg this way as there was not enough clearance to allow the bushings to come free. I suspect that a PO has rammed a washer in the seal well.). Its usually in tight enough to need a rattle gun to shift it, an ordinary allen key runs the risk of rounding the bolt head. A simple and cheap drain plug would make the job so easy.... cost accountants at work again.
to loosen them off and this with the fork leg in the vice I wouldn't fancy removing them with the forks on the bike although I'm sure it's possible,
IMHO best leave them alone unless your stripping the internals out.
I've now gone all European and bought a KTM Superduke GT and Aprilia RSV1000R ,
Storm is now gone . .
, Storm is now gone
. .