how long should fork oil last?
 

As above^, the clunk I had before, that was rectified by the changing of fork oil, has come back.

Re: how long should fork oil last?
 

considering it's been in the ground for some considerable time before you get it, I would imagine it'd remain stable for quite some time without outside influence ......... it is a working part, so like any other it very much depends on how much working it's been asked to do?

You could of course just grab a figure out of the air and say 15k or every 2 years which ever's the soonest, and given the cost (and perhaps the fact it's a secondhand bike so you've no idea of how the bike has been ridden before) it's prudent to change it anyway, but a better way would be the learn what the forks should feel like with decent oil in and then you'd know if yours need doing :smt102

Cheers Mark.

Re: how long should fork oil last?
 

Sookie, do you know if they found anything lose inside the forks last time they changed the oil? I do the forks on my competition bikes once a year or so but I've got road bikes that I haven't done for over five so as Rictus says how often it needs it will depend on the kind of use, or abuse, they get.

Sometimes the act of taking them apart to change the oil tightens up whatever is clunking, or it may be that the oil is borderline on your bike and as it ages and loses some of it's viscosity it stops acting as it should, either way an oil change is fairly simple to do.

Re: how long should fork oil last?
 

Thanks for the responses. It was me that did it last year and I still have some left so I could easily change it again, maybe best cause if in doubt n that. Next on my wee list is the twisting under heavy braking, thinking along the lines of left caliper needing stripped and greased. The education continues.

Re: how long should fork oil last?
 

The SV has a problem with clunking front forks, and if your clunk is the same, it's not anything to do with bad oil or anything wrong with the forks, it's to do with what kind of bump you hit.

If the fork gets slammed upwards (especially if whilst it's on the rebound), like the front wheel falling as you enter a pot hole, then banging back upwards as you exit the pot hole, the forks hit a hydraulic stop as the oil can't get through the holes in the damper rod quick enough, the compression damping rate is fixed and you just exceeded it. The only fix is lighter oil which may then not give you enough damping, or drill out the damper rod holes and fit a cartridge emulator.

You may think you had fixed the problem by changing the oil, but it may be that you just made it better by using an oil with a lower centistokes viscosity that can get through the holes quicker, or you just haven't hit the right (or wrong) type of bump since you changed the oil.

Re: how long should fork oil last?
 

Thanks Ralph, that makes a lot of sense. Do I just ignore the clunk or is it causing damage? It doesn't effect the handling, apart from the circumstances that cause the clunk in the first place obviously, just a wee bitty disconcerting is all.
A wee edit here, just a better description of the clunk. It came to light after I had lowered the horn to avoid the shorting out of fuses which resulted in the horn hitting the front mudguard after a dip/bump, schoolboy stuff I know, but I moved it again and the clunk remained.

Re: how long should fork oil last?
 

So long as we are talking about the same clunk, you just ignore it, annoying but don't damaging.

Re: how long should fork oil last?
 

I think I may have come up with why the clunk has returned. I recently had to go into hospital due to illness, doh, but due to this I had lost about 1 and a half to 2 stone so this has probably, definately, maybe changed the err sag, stiffness, general set-up type thing. So I'll fatten up and see if the clunk goes. :D

Re: how long should fork oil last?
 

Different bike I know but my Sprint ST service schedule gives an interval of 24000 miles or 4 years.

Re: how long should fork oil last?
 

Best check the seals if your doing an oil change.
But that ultimately depends upon the age and if the oil's uprated etc....