Topic: Fork Oil volume for "dry" rebuild? (CB500)

[DurangoCB]

I can find references to differing oil amounts for refreshing the oil in your fork vs. a full rebuild, but I cannot find the actual amounts for a 71 CB500, even in the FSM. 

The "wet" volume to add is 160cc.  Does anyone know what the approximate "dry" amount is to add? 

Failing that, what is the appropriate depth that the oil level should sit at with the top cap off and fork tubes fully compressed into the lowers?  I found folks saying that the CB750 should be set at 6", I think. 

Thanks in advance. 

[Deltarider]

It depends on the model. CB500 front fork legs underwent modification, but I suppose you have the old type. 160cc was prescribed, but I have better results with 10cc less. Actually I have 140 cc in them but mine are the newer type (the same as on the CB550K2). 7,5W works best for me.

[DurangoCB]

It depends on the model. CB500 front fork legs underwent modification, but I suppose you have the old type. 160cc was prescribed, but I have better results with 10cc less. Actually I have 140 cc in them but mine are the newer type (the same as on the CB550K2). 7,5W works best for me.

Thanks, Deltarider.  So there isn't a difference in the amount of oil you add when you just drain and refresh (for which 160cc is the recommended amount in the manual) and the amount you add when you've purged every last drop and cleaned/wiped out the legs, etc.?  I'll just go with the 160cc the FSM recommends for fork oil change. 

And I think it may have been you in another thread of mine where you mentioned that 15w oil seemed too heavy.  10w is what the manual recommends, but I have read here on the forums in old threads someone (forget who, maybe Hondaman?) recommending bumping it up to 15w for better performance. 

[dave500]

its a personal thing,see what works for you,you can buy fork oil in lighter grades like 2.5 or 5 etc,i just use atf about 150cc.

[Deltarider]

The CB500 suspension, both front and rear, is quite Spartan. 160 cc is the absolute maximum. Also Dave indicates a little less is better. With 160cc my legs were stonehard, but mine are the later type that requires less oil. As viscosity, I wouldn't go over 10W. Use fork oil or ATF, engine oil is a no no and multigrade is a joke imo.

[DurangoCB]

Great- doesn't sound like I can mess up the performance of the fork catastrophically by being a little over or under the ideal fork oil volume or viscosity.  Gracias, boys.

[PeWe]

Progressive forks have a general rule of max oil by measuring the fork when fully collapsed with no spring inside. 140mm from top.

My last springs my CB750K6 got were Wirth progressive springs with recommendation 160mm when fully collapsed and no springs. Fork oil Wt 10 included in the package. They were very alike my old from Progressive, same lenght. The last setup work really well. But I replaced the old plastic piston rings inside so the oil will work better inside. Old rings did not seal.