Topic: Fork Rebuild CB550F Question.

[Zaipai]

I just received a complete front end for my 75 CB550F so I would like to rebuild it since the one on my bike is very mushy. Question is what would be the best oil to use and what kind? Does it have to be Fork oil and if so, does it really have to be from Honda? Shops are far and few between here, so I thought I'd ask before I make the run. This front end I got is really much better so I will take it apart and check every thing, however I am thinking its just going to need new oil since it looks like what's in there is well used. Thoughts?

Thanks!

[1timduke]

ATF is recommended I believe in the Haynes manual.   Might want to get a bit more than needed so you can flush them a few times.

-Tim

[TwoTired]

You really want something with anti-foaming qualities, as the oil is being forced through small holes while doing it's damping action thing.
  This leaves you with two good options, IMO.  Either Auto trans fluid (ATF), which incidentally has additives to help keep the seals vital.  Or, fork oil, which has everything you need  fork oil to do.

Personally, I think the damping action is a bit wimpy with the standard 7-ish weight viscosity of ATF.  So, I use fork oil in 10 Wt  (some prefer the 15W. But, I find that slightly on the harsh damping action for my tastes).
The oil weight kinda depends on the lbs weight you are putting on the bike and how much you want the tires to conform to washboard roads while leaned over.  If you are riding over a lot of pot holes, you'll want the thicker weight oil, too, in order to reduce suspension travel bottoming on the front end.

It's a matter of taste and what goals you have, which you did not state.

Cheers,

[Zaipai]

You really want something with anti-foaming qualities, as the oil is being forced through small holes while doing it's damping action thing.
  This leaves you with two good options, IMO.  Either Auto trans fluid (ATF), which incidentally has additives to help keep the seals vital.  Or, fork oil, which has everything you need  fork oil to do.

Personally, I think the damping action is a bit wimpy with the standard 7-ish weight viscosity of ATF.  So, I use fork oil in 10 Wt  (some prefer the 15W. But, I find that slightly on the harsh damping action for my tastes).
The oil weight kinda depends on the lbs weight you are putting on the bike and how much you want the tires to conform to washboard roads while leaned over.  If you are riding over a lot of pot holes, you'll want the thicker weight oil, too, in order to reduce suspension travel bottoming on the front end.

It's a matter of taste and what goals you have, which you did not state.

Cheers,

Thank you both for the info. Looks like I go with the fork oil in the 10wt. My goal would be to get it as close to the what it was stock, given that its a 550 and tends to be a soft ride, I would not mind if it were a little firmer. I live where there are many wide open roads for miles with some small hills few turns and pot holes that can be avoided easily. That said I may take it into Milwaukee and or Chicago from time to time for bike events. 10wt seems from your description to be just what I need.

Thanks again! And have a great weekend!