Replacing fork oil - which oil for my weight?

[hongman]

Hi all

Weather/time permitting I am planning to replace my fork oil in my 02 Curvy SV this weekend or next - want this done before the AR really.

I have no evidance that the fork oil on this has ever been changed, at 24.5k miles. Rictus said it would probably be "like p1ss water" by now, and felt like it.

Granted, having no experience on bikes and on the SV, it feels "soft" to me. But I have nothing to compare to!

I'm 8st, prob ~9st with gear + odd bit of luggage.

So...

At my weight, what weight oil do I replace it with?

Wondering if the original weight oil will be ok as new, bearing in mind the bike was designed for someone my weight-ish. Or would I benefit from heavier oil regardless...

Do I really need to do springs as well? I want to make as much of an improvement right now as posible, but keeping costs down (v. important).

TY

[jambo]

Fresh 10w oil, or 12w oil (1 bottle of 10w and a bottle of 15w mixed) would do you fine I reckon.

[hongman]

First I've heard about mixing oil :O

[hongman]

Oh, the manual says something about replacing the o-ring seal.

Is this a must?

[andrewsmith]

if it needs it yes. Best to get a set of seals from wemoto 'just in case'. I'm expecting to have change the seals on my 2000 curvy (with 7k on it) when a do a rebuild

[hongman]

O, thanks.

Just made an order with wemoto yesterday, doh.

[jambo]

Unless the seals are leaking, or you are dis-assembling the fork for some reason, you shouldn't need fork seals or bushes to change the oil. That is, for the 20+ fork oil changes I've done I've never replaced an oil seal while just replacing the oil.

Make sure you read the instructions or get supervision, and don't just undo the damper rod bolt at the bottom of the fork, it's not a drain bolt...

Remove the forks, unto the caps and drain them properly.

Jambo

[Sid Squid]

if it needs it yes. Best to get a set of seals from wemoto 'just in case'. I'm expecting to have change the seals on my 2000 curvy (with 7k on it) when a do a rebuild
Unless the seals are leaking do not disturb them - the 'O' rings being referred to are the thin seals around the fork cap, not the fork seals, it is unusual for said 'o' rings to be damaged and need replacement, but of course they should be checked.

It is not necessary to dismantle the fork to change the oil, only the top cap needs to be removed.

[andrewsmith]

or get a mate who know what they're doing to do it

[hongman]

or get a mate who know what they're doing to do it

Hmm, I think I best get supervision for the first time doing this.

I'll stick a post up in my regional section when the time comes.

Thank you all.

[2hys]

i need to change the oil in my forks soon, let us know how you get on, and how you went about it, its somthing ive never done, but need to do....

[hongman]

Will be glad to.

Just one thing to ask... Is there a proper way to mix oil? Or can I just mix by emptying both weights into a bigger bottle and giving it a shake?

[yorkie_chris]

Unless the seals are leaking do not disturb them - the 'O' rings being referred to are the thin seals around the fork cap, not the fork seals, it is unusual for said 'o' rings to be damaged and need replacement, but of course they should be checked.

It is not necessary to dismantle the fork to change the oil, only the top cap needs to be removed.

+1 to top bit

+1 to bottom bit too, but FYI of anyone who has cartridge forks, it is well worth complete disassembly of these forks to get all the crap out.

Will be glad to.

Just one thing to ask... Is there a proper way to mix oil? Or can I just mix by emptying both weights into a bigger bottle and giving it a shake?

Mix it up and shake it is fine, for the SV forks, it's not an exact science.

[hongman]

So haynes seeming overcomplicated instructions aside, am I literally just removing the forks, undoing the top cap and emptying the oil out, replace with frsh?

If so i reckon I could manage that. Haynes looks like you fisassembe the whole thing unless I'm Reading wrong (possibility...)

[yorkie_chris]

remove forks
take off cap
shake out spacer, spring, washers
leave upside down, 10 minutes
pour in 1 pint white spirit/paraffin, pump leg up and down, put your hand over the top and shake fork about.

pour out, pump out, leave upside down for 30 minutes or more to get it all out
add new oil
pump leg and leave to stand for 5 minutes
check/adjust oil level.

clean all spring, spacers, washers and put back in fork... put it back on bike.


Tips of the day
- you won't need 2l of oil. Don't mix some, just buy a heavy 10w or a light 15w, buy a viscosity you actually want, not 2 that you don't.
- crack the top caps off BEFORE removing the forks from the yokes

[Sid Squid]

FYI of anyone who has cartridge forks, it is well worth complete disassembly of these forks to get all the crap out.
Agreed, was of course referring solely to standard SV forks.

[Sid Squid]

So haynes seeming overcomplicated instructions aside, am I literally just removing the forks, undoing the top cap and emptying the oil out, replace with frsh?

If so i reckon I could manage that. Haynes looks like you fisassembe the whole thing unless I'm Reading wrong (possibility...)
Take another look, Haynes aren't overcomplicating things, I think you're possibly reading the whole section on disassembling the forks.

[hongman]

remove forks
take off cap
shake out spacer, spring, washers
leave upside down, 10 minutes
pour in 1 pint white spirit/paraffin, pump leg up and down, put your hand over the top and shake fork about.

pour out, pump out, leave upside down for 30 minutes or more to get it all out
add new oil
pump leg and leave to stand for 5 minutes
check/adjust oil level.

clean all spring, spacers, washers and put back in fork... put it back on bike.


Tips of the day
- you won't need 2l of oil. Don't mix some, just buy a heavy 10w or a light 15w, buy a viscosity you actually want, not 2 that you don't.
- crack the top caps off BEFORE removing the forks from the
yokes

Cheers YC. I thought the "w" indicated the weight of the oil, but now you said "a heavy 10w" I'm not sure I know what you mean.

Take another look, Haynes aren't overcomplicating things, I think you're possibly reading the whole section on disassembling the forks.

Aye, quite possibly!

[andrewsmith]

there is actually an illustrated guide of what YC has said in Augusts superbike mag!!!
Just been reading it and is pretty much the same

[yorkie_chris]

Cheers YC. I thought the "w" indicated the weight of the oil, but now you said "a heavy 10w" I'm not sure I know what you mean.


The scales are a mess, SAE scales, meant for different oils and not standardised for suspension fluid.

E.G pro RSF7.5 is heavier (higher viscosity) than showa ss8 10w (stock, AFAIK)


So taking the example of making your own 12.5w from silkolene fork oil, the 10w is 34cSt, the 15w is 48cSt meaning the mix (equal proportions) would be 41cSt.

Or you could use some castrol synthetic fork oil 10w which has a viscosity of 42cSt to start with and save messing.

[hongman]

Lots of stuff you dont understand

Or you could use some castrol synthetic fork oil 10w which has a viscosity of 42cSt to start with and save messing.

Think I'll do that!

[yorkie_chris]

the cSt number, centiStokes, is the actual viscosity of the fluid, the resistance to shear stress caused by flow. This gives you damping, it is this that you feel.
The 10W/15W/whateverW number is arbitrary.

[hongman]

Ah, I see.

Learn something new everyday. ;)