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Discussion Starter · #1 ·
I have a leak in one of my fork seals and do not want to bother changing it out. Can I just top off the fork oil periodically? How do I know how much to add without draining the fork and starting empty? Is there a "full" mark on the inside of the fork? I don't want to overfill. Any suggestions? Thanks.
 

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First, let me qualify that I have a GL500 and my only "official" reference is the Honda shop manual. There is no spec for a drain and refill, just for a refill after disassemble; not sure if that is the case for a CX500 or if other third party manuals have a procedure/specification for this. Plus given that you don't indicate model and year and that fork capacity varies between years/models, it would be difficult for a forum member to give you their specifics. Let us know or better yet, update your profile to indicate your bike year and model.



You can never quite drain all of the oil out, there will be some latent oil left over unless you completely disassemble. So you stand a chance of overfilling by adding the amount specified in the service manual for the complete rebuild after you drain. How much, I don't know, since I have never gone through the excercise of starting out with a completely dry system, filling to the prescribed amount, draining and measuring what came out. It may be negligible or it may not be. Others may have more experience to address this aspect.



Given that you want the two forks to have the same amount oil, one suggestion is that you carefully remove the springs in both, measure the height of the oil in the one not leaking and filling the leaking one to that level. They will both be even but you won't know if they are under, over or filled just right. Plus, you stand a high chance of having two different viscosities using this approach.



Or, drain both, pump the heck out of them to remove as much latent oil as you can, refill with the specified amount for a rebuild and measure the height. They may be a bit overfilled but at least they are both even and have the same viscosity oil in them. With this approach, you may wish to flush and drain a few times to remove all of the old oil so they are both nice and clean



In either case, you've established a repeatable measurement for when you wish to top it off.



That said, unless this is a temporary approach, I highly suggest that you bite the bullet and replace the seal. Personally, I would not be comfortable not knowing how much oil is in the leaking leg. And there is always the danger of the oil leaking onto your brakes, diminishing your stopping power.





Greg
 

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Mine is a 1978 CX500. I found a set of forks on ebay so I am going to swap out the leaking one. The seller said the seals were good and I did not pay that much, so we'll see.
mmm,you realise you cant keep swopping part,to avoid a little work?....
 

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I agree with Bandit, swapping is not a long term solution when you don't know what you are getting. The replacement ones could have low or no oil in them or very dirty oil. The seals may be good but the internal bushings may be worn. You've gone from two unknowns to four unknowns.



At the very least, if you have a real burning desire to get on the road as soon as possible, I suggest that you replace both legs when you get the used set. So much chance of a mismatch by using just one one leg. One of the sets could have stock springs and the other have replacement progressive springs or an additonal pre-load spacer. Also, there would be different rates of wear in the internal bushings between the two sets.



This is a safety item not a cosmetic one. Rebuild one of the sets as soon as possible.





Greg
 

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The proper way to check fork oil is to take the forks out of the clamps. Remove caps, remove springs, drain old oil, wash the internal fork. With the fork compressed and vertical and the spring still out fill each fork to the exact same level, say four inches down from top of fork tube. Very slowly pump forks a few times then check level again. Then insert spring and cap the forks and put them back in the clalmps. There may be other details that a pro might do but that will get you really close.

To have different amounts of fork oil is a bad deal, there is no "full" mark like the dip stick. More or less oil will effect your spring rate too.

Cheers, 50gary
 
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