fork oil ?

Im changing the fork seals on my cb tomorrow. what is the best type of fork oil for smooth handling to replace my current oil? also what volume will fill both? thanks

Think I used 10wt but as far as volume goes your better off working to the air gap rather than a set amount.

i went for 20w and 120mm air gap, firmed the front up nicely. 15w wasn't firm enough and I've read that 25w is overkill.

geewhizz wrote:i went for 20w and 120mm air gap....

That's what I did. Worked a treat.

Air gap will depend on the age of your bike.  Honda changed the size of the spacer & oil level a few times over the years.

Haynes? I did mine according to said reference and am happy as a lark...

Hi,
seconded, Haynes gives different air gaps depending on year.
As to oil, standard is 10w. 15 or 20 will firm up the front a fair bit. However, you can't adjust the spring tension on the rear shocks, just the ride height so getting a bike that rides well on the roads you ride is down to personal preference. Be prepared to have a couple of goes to get something you are happy with. If the front of the bike feels high (as it will with firmer oil) you could drop the forks through the yokes a few mm.

Btw, hagon springs, which do firm up the front a fair bit, use 7.5w oil.

atb

muttley1

So i changed the oil and dodgy seal on the right fork of my bike. myself and my uncle who is very mechanically minded took 2 hours getting the old seal out. it was seized in place in the end we had to get a dremel down the gap and cut the metal ring in the seal to pull it out! I fitted the new seal, some oil leaked out at first as it settled but now it is gone.

sinclairmic wrote:So i changed the oil and dodgy seal on the right fork of my bike. myself and my uncle who is very mechanically minded took 2 hours getting the old seal out. it was seized in place in the end we had to get a dremel down the gap and cut the metal ring in the seal to pull it out! I fitted the new seal, some oil leaked out at first as it settled but now it is gone.

FYI - it might be better to (at least) change the fork oil in both legs to make sure the damping is the same on both sides...

The fork seals can be a bit of a pain to get out (as you found), especially if they have been in for a good while.

Just open the oil cap on the bottom of the fork. Empty it then refill with the same oil as the other side?

Not all the CB500 forks have oil drain bolts... only the earlier ones!

I think most of them have the casting but don't have the hole tapped, so you could probably make some if you wanted.

You can take off the cap, out with the spacer, put a piece of sellotape over to stop the spring coming out, hold it upside down and pump it into a container, mark the level, empty and refill with fresh oil to the same level and pour it in. 

I think you are meant to change fork oil every 5,000 miles or so.. all that scraping of the spring makes metal filings degrades the oil and stops the damping working. Fresh 10wt made a nice improvement for me.

I've had different experiences with 15W.

On one of my bikes, it stiffened everything up considerably. Better feel in the bends, but a little bit stiff for longer roadtrips.
On the other bike, same year, but different 15W brand, it didn't actually change a lot, felt like the older 10W stuff! Bizarre.

In the future, I'll stick to the branded stuff, and probably mix 2/3 15W and 1/3W, should be a good compromise. I'm surprised people use 20W, unless the bikes are for track use?

Is there any danger of 20W bursting the seal?

nae i've had 20w in for a while now and its fine, as noted the track/race guys seem to favour 20w and there bike probably get punished a bit more than ours. fair enough we have to deal with potholes but i wouldn't worry.

peatrich wrote:Is there any danger of 20W bursting the seal?

No, the only danger is the suspension will be too stiff for the road and the front tyre could skip over rough surfaces and loose grip or lock up easier under braking.

The handling on mine improved a lot just with new seals and oil, everything set up totally standard with 10W.

Fork oil does vary quite a bit - one manufacturers 10 may be like another manufacturers 15 etc.