Topic: CB550K1 - correct amount of fork oil?

[Erny]

Reading HSM, forums and still did not find clear answer, what is prescribed amount of fork oil for CB550K1 1975

HSM says :
for CB500 bikes (early versions certainly) :
- 160cc for 500 forks in "Maintenance operations" chapter (3), changing oil w/o fork dissassembly)
- 155-165cc in "Chassis" chapter (5) for dry, dissassebled fork

for CB550F (chapter 16, "Supplement to CB550F") :
- 165-170cc for dry fork.
550F fork is different to CB500/550K

for CB550K1 I only found fork mentioned in chapter 8 "New features of the CB550", but there is only fork description and differences between CB500K fork. They do not mention about fork oil amount

Moreover there is wrong info about spring length for 550K1 fork...So I do not trust this manual too much for 550K1

Does anybody have reliable information please?

[Deltarider]

It is confusing. I found out by comparing the parts numbers. Turns out my legs are the same as on the CB550(K0), CB550K1 and CB550K2. I have best results with 140-145cc 7,5 wt. Legs 'F' and 'K' models differ. I know the length of springs is incorrect, but I wouldn't worry. They live forever.
Read: http://forums.sohc4.net/index.php/topic,151936.msg1736598.html#msg1736598

[caluser2000]

Is this from full disassembly, clean, reassembly(rebuild) or just replace the old oil with fresh fork oil to  in general routine maintenance on your forks? The qty differs for each. Rebuild needs more.

The Clymer and Haynes manuals specify 160ccs for each fork after rebuild.for 500/550s  165-170ccs for 550F rebuild according to the my '77 OEM workshop manual..My CB550F owner manual specifies  145-150cc wet for scheduled routine maintenance, ie  remove then replace fork oil while forks in the m/c completely assembled.

Around 20ccs difference between wet and rebuild qtys for all 500/550k/550F m/cs.

Fluid height from the top of the fork would be far easier like most other manufacturers do.

[Deltarider]

Quantity in the Owner's Manual, is 'wet', without taking things apart. BTW, thanks to those wonderful harmonicarubbers, I didn't have to renew one fork seal yet. Just check the tiny vent hole faces towards the rear.

[robvangulik]

Fluid height from the top of the fork would be far easier like most other manufacturers do.

That became usual long after these bikes were built!

[caluser2000]

The fork boots don't last for ever though. The OEM ones on mine when I got it were cracked around the outside edge of the boots. The replacement OEM ones have lasted longer though

And yes they protect the fork seals very well. I have not replaced any fork seals since I rebuilt the bike back in 1990 or so.

[caluser2000]

Fluid height from the top of the fork would be far easier like most other manufacturers do.

That became usual long after these bikes were built!

Well we could have a collaborative effort to rectify that.

What do SOHC forum members think about that?

[Deltarider]

It is my believe that the 'F' models have a level mark inside. Cf.: point 3, p.157 of the Shop Manual Honda CB500-550 http://manuals.sohc4.net/cb500/service_manual/HSM500550_14.pdf

[caluser2000]

It is my believe that the 'F' models have a level mark inside. Cf.: point 3, p.157 of the Shop Manual Honda CB500-550 http://manuals.sohc4.net/cb500/service_manual/HSM500550_14.pdf

Not on mine it doesn't.

That is not a fork oil level mark.

Why would you have a fork oil lever line inside were you can not see it?

I've got the dead tree version of the '77 edition of the 500/550 workshop manual.

[robvangulik]

I think such a mark on the inside wouldn't even be visible from the top of the leg. On my CBR, with 41mm legs and the level at 140mm from the top ( without spring and with the fork fully retracted) it wouldn't be visible....I always use fuel hose of ample length marked at 14cm and blow through that while filling until I hear bubbling

[flatlander]

if it helps: i have replaced the springs in my 550F with new ones from wilbers. they recommend to fill up to 160mm from top.

[caluser2000]

if it helps: i have replaced the springs in my 550F with new ones from wilbers. they recommend to fill up to 160mm from top.

That is useful info flatlander. Cheers for sharing it.

[Deltarider]

Yeah, that's useful info, Flatlander. That is: if you have chosen Wilbers springs ofcourse, but that's just a minor detail. Anyway, cheers for sharing it.
What is described in p. 157 is not a routine servicing, like in a Owner's Manual. In the addendum it concerns a complete dissassembly and reassembly. With the leg out, I don't see why you wouldn't see the mark, if it's there. Other bikes have them. Ask Honda. I didn't compose that Shop Manual. Honda did.

[Erny]

I already put 160cc in each leg (wet). Probably too much?

[Deltarider]

Erny, just see if you like it. I made my own estimate, taking into account my weight, my riding position and the Koni's in the rear. The CB500 is quite spartan, so I wanted to have as much travel possible, just short of bottoming out.

[flatlander]

I already put 160cc in each leg (wet). Probably too much?

depends... do you remember how much air you have at the top?

[caluser2000]

Yeah, that's useful info, Flatlander. Cheers for sharing that.
What is described in p. 157 is not a routine servicing, like in a Owner's Manual. In the addendum it concerns a complete dissassembly and reassembly. With the leg out, I don't see why you wouldn't see the mark, if it's there. Other bikes have them. Ask Honda. I didn't compose that Shop Manual. Honda did.

I you have worked on 550 forks often enough you KNOW you don't see that mark. Ithe has absolutely nothing to do with fork oil level.

Try reading what folk here have experienced servicing their motobicycles. Not what you THINK you know.

[Erny]

I already put 160cc in each leg (wet). Probably too much?

depends... do you remember how much air you have at the top?

no at all, I did it with mounted handlebars, so there was just just space to fill oil in, with spring inside. No chance to see oil level distance from top

[flatlander]

that would make me paranoid. i'd want to know how much air there is above the oil. that is more important than volume of oil.

[caluser2000]

that would make me paranoid. i'd want to know how much air there is above the oil. that is more important than volume of oil.

If he is not having any leaks or handling issues there is nothing to worry about.

[Deltarider]

Yeah, that's useful info, Flatlander. Cheers for sharing that.
What is described in p. 157 is not a routine servicing, like in a Owner's Manual. In the addendum it concerns a complete dissassembly and reassembly. With the leg out, I don't see why you wouldn't see the mark, if it's there. Other bikes have them. Ask Honda. I didn't compose that Shop Manual. Honda did.

I you have worked on 550 forks often enough you KNOW you don't see that mark. Ithe has absolutely nothing to do with fork oil level.

Try reading what folk here have experienced servicing their motobicycles. Not what you THINK you know.

Sir, I think less than you think I do. I just gave the info available. As far as your experience: who could doubt yours. You have impressed all of us here by spotting a clearance in my front brake pivot pin that I have not noticed in over 40 years. Not only that. You did it with a pinpoint accuracy of 1,5-2mm, and that from New Zealand, the furthest distance possible from where I live. You couldn't have made a better entrance in this forum. Cheers!
For those who may find it difficult to believe:
http://forums.sohc4.net/index.php/topic,186362.msg2160383.html#msg2160383

[caluser2000]

Yeah, that's useful info, Flatlander. Cheers for sharing that.
What is described in p. 157 is not a routine servicing, like in a Owner's Manual. In the addendum it concerns a complete dissassembly and reassembly. With the leg out, I don't see why you wouldn't see the mark, if it's there. Other bikes have them. Ask Honda. I didn't compose that Shop Manual. Honda did.

I you have worked on 550 forks often enough you KNOW you don't see that mark. Ithe has absolutely nothing to do with fork oil level.

Try reading what folk here have experienced servicing their motobicycles. Not what you THINK you know.

Sir, I think less than you think I do. I just gave the info available. As far as your experience: you have impressed all of us here already by spotting a play in my front brake pivot pin that I have not noticed in 40 years. Not only that. You did it with a pinpoint accuracy of 1,5-2 mm, andd that all from New Zealand, the furthest distance possible from where I live. You couldn't have made a better entrance here. Cheers!

You are most welcome. After all this HONDA SOHC/4 is supose to help people not imagine something is what it isn't

Over the years I'v done hours and hours researching about the 500/550/650 range of middle weight fours. In fact I prefer them over the SOHC 750s even though I am six foot tall.. I had a SOHC CB750F2 for a bit. A buddy ask if I would sell it to him. I did at the same price I bought it for. He did a wonderful job of cleaning it up. If I had kept it would have sat in the shed getting very little attention I'd be riding the small framed twin shock BMW R65 or CB550F the majority of the time.

[Kevnz]

As a matter of interest, would anyone even notice the difference of 20ml in a fork? If you hopped from one bike to another, each with the different level, what difference would you detect? Maybe I  am not so sensitive to these things. Obviously, the factory specifies a level, but people often change these things either through ignorance or personal preference, possibly without ever quantifying the difference.

[caluser2000]

As a matter of interest, would anyone even notice the difference of 20ml in a fork? If you hopped from one bike to another, each with the different level, what difference would you detect? Maybe I  am not so sensitive to these things. Obviously, the factory specifies a level, but people often change these things either through ignorance or personal preference, possibly without ever quantifying the difference.

Exactly...The fork oil weight will have a bigger effect.

[robvangulik]

Sorry, I don't agree there, the size of the air chamber in a front fork is very important, I use more, but lighter oil in those CBR's to keep the damping light enough to cope with my (light) weight, and prevent slamming through the forks while braking hard. And a CBR1000F has been my main means of transport for 30+ years, I think I know them inside and out