YZF USD forks: servicing/manual..

[trixynut]

Anyone got some basic pointers on servicing these puppies: oil change is all I need. So far...

1. Took the top cap out with a 30mm socket, but when I pull it up to try to take it out, the inner tube slider/brake holder at the bottom of the leg all comes up with it! so...

2. Found a 10mm bolt at the bottom of the fork leg, thought this must be holding it all together. Undid it, and fork oil poured out! so...

3. Kicked the cat, had a smoke, sat and looked at it for a bit, then went inside and watched the telly.

I've never had a bike with USD forks before, but I'm sure it ain't that tricky.



Anyone know the basic method for dismantling these forks to drain out old oil and then refill please?

AND anyone got a YZF750/Thunderace Haynes manual or a Yamaha workshop manual they could copy/post or scan/email the fork servicing pages from it to me please again?

Cheers

Dave.

[youngy]

Wind out the compression and rebound dampers all the way. Undo the top cap.

Under the top cap there should be a locknut. Undo this and then you should be able to unscrew the cap from the rod. To access the nut you will need to push the spring down - it will probably hide the nut from view.
You can then upend the fork, and the oil will start to pour out along with the spring and any washers or spacers.
You must pump the oil out vigourously on a cartridge fork, as the orifices are so small.

When filling, pour the oil in slowly and pump the fork up and down to ensure that the oil is going in and air is coming out. You will hear a difference in the noise it makes when all the air has been expelled. Make sure it has time to settle and all the air bubbles can get out before you set the level.

Replace the spring and washers.

When you replace the top cap you must set the preload adjuster to (I think) 25mm depth for the rod to screw into, then lock the locknut. If you don't set this to the correct depth you will loose rebound adjustment.

Alternatively take them to K-tech at Coalville.

Any questions, shout em out.

Part diagram:

http://fiche.ronayers.com/Index.cfm/Mod ... FRONT_FORK

nut in question is part 15 and 33

[honkdawillydahonk]

I've got a YZF manual if you need copies....

Personally I find USD forks easier to work on....

[Tarwetijger]

I've got a YZF manual if you need copies....

Oops, of course I have a digital copy too, but it is too big for e-mail (like 200 MB or something like that).

Personally I find USD forks easier to work on....

I do almost everything myself on the bike(s) but especially the UPSD was done by a specialist.

[trixynut]

Thanks for that.

The description is useful thanks Youngy: I'll have another look at the weekend.

Still not quite sure how the 10mm bolt at the bottom of the leg fits into the equation though? I took it out and oil came out: is it holding the damper rod or cartridge or something in place? Any thoughts?

Honk, I've pm'd you my address and email. If you could copy/scan a couple of pages on the fork strip/rebuild and post/email them, that would be great. I'm too tight to spend £20 on a manual, but would like to see what Mr Haynes has to say on the matter!

Cheers,

Dave.

[youngy]

The 10mm bolt at the bottom (item 12) holds the cartridge (item 10) in. You don't want to remove that

[Tarwetijger]

Thanks for that.

The description is useful thanks Youngy: I'll have another look at the weekend.

Still not quite sure how the 10mm bolt at the bottom of the leg fits into the equation though? I took it out and oil came out: is it holding the damper rod or cartridge or something in place? Any thoughts?

Honk, I've pm'd you my address and email. If you could copy/scan a couple of pages on the fork strip/rebuild and post/email them, that would be great. I'm too tight to spend £20 on a manual, but would like to see what Mr Haynes has to say on the matter!

Cheers,

Dave.

Go ahead and PM me your email address too. I can make a cut-out for the part about the forks, that's way smaller then 200 MB of course.

[Tarwetijger]

The 10mm bolt at the bottom (item 12) holds the cartridge (item 10) in. You don't want to remove that

It holds the cartridge indeed but it comes out in one piece, so it is not a big deal.
But if you only doing an oil change, I think you don't need to take it out anyway.
Or maybe you will, to pump the last bit of old oil out of it.

[Tarwetijger]

Look what I've found:
The full Haynes YZF manual, online on a Dutch FZR-enthousiasts website.
Be warned though, it's 200 MB, so it will take a while.

[trixynut]

Tarwe,

Brilliant, thanks.

I was just about to bid on one on Ebay!

Downloaded it and yep, it's 206mb and took ages!

Had the forks apart: with the 10mm bolt out the bottom, the cartridge comes out, so took it out and left the cartridge as is in one bit, drained all the oil, and refilled as per Honks volumes.

Tricky bit is putting the bolt back in the bottom of the fork leg and getting it tight as it screws into the cartridge, but won't tighten as the whole lot turns round and there's no way of holding it. Must be a special Yam tool to do it: I'll consult my manual....

Tightened up eventually.

Dave

[youngy]

That's why you don't want to undo it. they can be very difficult to retighten.

[trixynut]

Yup, you were right on that one Youngy m'boy ..... but I'd already done it by then! (the old "Hmm, wonder what this bolt does....oh sh!t" syndrome!)

But now I've got a free manual ..... happy as a dog with two tails...... might just go and take that bolt out again and then put it back in ..... just for the hell of it!!

And to make things even better, someone has just outbid me on the one I was bidding for on Ebay. Phew! That would have been a waste of £15 !!

Thanks all.

[youngy]

nice one Dave. Well done. Your old forks......................what you doing with them??

[trixynut]

I'll be keeping them: if I change something on the bike I tend to keep the original bits so if I ever "sell up and move on" I can put the bike back to standard to flog, and then flog all the 'bling' bits separately.

[cal]

Anyone got a manual for YZF750 forks, the link to the dutch site has gone?..

Couldnt help myself,... got the spanners out, took off the top cap, but it seems to be attached to the rest of the internals....

Streetfighter bars on as well so they will have to come off too was kind of hoping to leave the forks in the yokes or is it best to whip them out?

thought it would be worth asking first before getting too far in.....