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Slipping clutch xs400 (1982)


S.Gjaltema
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Hello,

I have a bit of a problem.

After changing the engine oil (SAE 10W40 Castrol) the clutch is slipping. :(

The bike has run 30.000 miles, do i need new plates, or another engine oil?

There is some slack on the clutch-cable.

Appreciate any help.

kr,

Sicco.

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I have a bit of a problem.

After changing the engine oil (SAE 10W40 Castrol) the clutch is slipping. :(

The bike has run 30.000 miles, do i need new plates, or another engine oil?

There is some slack on the clutch-cable.

If you put the castrol synthetic or semi-synthetic in there you may need both a different oil AND new clutch plates. AFAIK wet clutch plates must be designed for synthetic or you need synthetic designed for motorcycles which is not as slick as normal synthetic. This is unless you have aftermarket plates that are made for synthetic which I'm not sure area available for XS400's. You might be able to get away with just changing back to normal dino oil if you put synthetic in there and it hasn't been there too long though.

This is of course all based on my understanding of how theses things work, as modern oils just barely let my clutch lock up as it is, without putting synthetic in there. (BTW I have 43000 miles on mine).

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If you put the castrol synthetic or semi-synthetic in there you may need both a different oil AND new clutch plates. AFAIK wet clutch plates must be designed for synthetic or you need synthetic designed for motorcycles which is not as slick as normal synthetic. This is unless you have aftermarket plates that are made for synthetic which I'm not sure area available for XS400's. You might be able to get away with just changing back to normal dino oil if you put synthetic in there and it hasn't been there too long though.

This is of course all based on my understanding of how theses things work, as modern oils just barely let my clutch lock up as it is, without putting synthetic in there. (BTW I have 43000 miles on mine).

Thanks a lot,

It was indeed the new synthetic oil of Castrol, so i think you're right.

I just made a few miles to test the bike with this oil and immediately the ride i drained the engine.

So i hope with new "old" oil the clutch won't slip.

kr,

Sicco.

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Thanks a lot,

It was indeed the new synthetic oil of Castrol, so i think you're right.

I just made a few miles to test the bike with this oil and immediately the ride i drained the engine.

So i hope with new "old" oil the clutch won't slip.

kr,

Sicco.

Yipee, problem solved.

I changed the engine oil and used a non-synthetic oil.

And miraculous the clutch isn't slipping anymore.

kr,

Sicco.

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Yipee, problem solved.

I changed the engine oil and used a non-synthetic oil.

And miraculous the clutch isn't slipping anymore.

Yep, clutches designed for synthetic have rougher friction material than the older bikes used. I'm sure that even they don't grip as well either since synthetic is so much better at reducing friction than conventional.

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Yep, clutches designed for synthetic have rougher friction material than the older bikes used. I'm sure that even they don't grip as well either since synthetic is so much better at reducing friction than conventional.

I put semi-syth millars 20/50 in mine, which is a fossil based cracked oil.

I did post a similar reply in another thread, whereas I said synth was too slippy for the clutch and I got derided :P

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I put semi-syth millars 20/50 in mine, which is a fossil based cracked oil.

I did post a similar reply in another thread, whereas I said synth was too slippy for the clutch and I got derided :P

All I can say on that is that it wasn't me who did that. <g> I respect the all the good advice that you give on here to the other vintage riders.

Slightly off topic (before starting a new thread) I just discovered I didn't dodge the fork seal bullet (hoping that my seals hadn't gone south while the bike was stored), anybody have the easiest procedure for changing them on a 1980 XS400? I know I have to do it (started leaking on my first sustained high speed ride since putting it back on the road) and I know I can get them on ebay for a decent price, but I have heard horror stories about changing them (while I'm at it I may well attack the upper engine seals as well.)

Any help here?

PS: Yes the bike in question is the one in my avatar.

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All I can say on that is that it wasn't me who did that. <g> I respect the all the good advice that you give on here to the other vintage riders.

Slightly off topic (before starting a new thread) I just discovered I didn't dodge the fork seal bullet (hoping that my seals hadn't gone south while the bike was stored), anybody have the easiest procedure for changing them on a 1980 XS400? I know I have to do it (started leaking on my first sustained high speed ride since putting it back on the road) and I know I can get them on ebay for a decent price, but I have heard horror stories about changing them (while I'm at it I may well attack the upper engine seals as well.)

Any help here?

PS: Yes the bike in question is the one in my avatar.

Well, guess what I'm doing at the moment ;)

Jack the bike up, or leave on main stand but raise 2" off ground

undo caliper and tie up from frame (or if drum don't do this)

Take off speedo drive and front wheel

undo the clamps for the legs and twist down and off the bike (that's why you jack it up)

tricky bit.....

use an 8mm (i think) Allen key under fork leg and clamp leg in vise. (you have left the springs in didn't you?)

using a shock/snap motion, loosen and undo the bolt. you still have oil in so be careful. leave standing on a bowl to let oil drain out (pref overnight)

If the bolt turns but doesn't undo, come back on here as now it becomes a pain.

Repeat for the other leg

get the wife to take out the circlip whilst you push down on the top spring securing plug. (my missus has done this before and is really good at it. If you're lucky you can get her in a position so her tits rub on your arm, Bonus!!)

take off the lower fork leg circlip

Prise out the seal with a tyre lever and use heat. Mine has come out easy as i did this a few years ago and greased (ACF50) the seal

watch for a spacer under the seal

clean all the crud at the bottom of the leg

drift in the new seal making sure it is the right way up

anneal the copper washer for the allen bolts and check for any signs of wear

reverse procedure for assembly (inc the missus help!)

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Hy,

I've just changed both seals on my front fork legs.

I had no problems doing that, they came out easely.

But instand of using my wife ;) i used a self made lever to push down the spring while removing the circlip.

kr,

Sicco.

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