Bimota Forum

[oily]

Many second opinions needed please.........

Mrs Oily has been out on the SB6 this morning and is complaining about the severe clutch drag.
Obviously, i haven't got around to sorting this yet but I need to get it done this week.
When I bought this one, the clutch slave cylinder was leaking like a good un so I put a seal kit in it and then changed the oil for FULLY synthetic.
obviously, with drag as opposed to slip, the plates should be alright so that leaves the hydraulic system or the oil?
It had a brand new Brembo master cylinder on it just before I bought it but don't know which model.
This problem appears as the engine warms up, the warmer it gets the worse it is
Could it be
a) the motul 300v fully synthetic
b) wrong master cylinder
c) dodgy slave cylinder
d) none of the above

My first step was going to change the oil and filter again for Semi synthetic but before I chuck another £25 down the drain (not literally
0) I thought I'd ask your views guys

[zombie]

Hi Oily,
Do you know whether the slave cylinder is being fully actuated when you pull the clutch in.

If its not I would suspect the master cylinder is not pushing enough millilitres of fluid through to do the job properly, or maybe the system just needs bleeding. With the Brembos sometimes it can be worth removing the master cylinder from the handle bar to tip them up to get the last bit of air out near the top banjo bolt.

If it gets worse with engine temperature, I would have guessed that it isnt the oil but not sure how the modern synthetic stuff performs to be honest!

Zombie

[oily]

Thanks for the input Zombie
The bit that's throwing me is the fact that it gets worse the higher the engine tempreture.
How would I tell if the slave is being fully activated?
Can't see it, can't even get at it to bleed it without dropping the engine.
Just need all the options before I get the shiney spanners out.
When It's pulled out of the garage and pull away, it's perfectly useable,
10 minutes down the road, pulled up at a junction, you cant select gears(with the engine running) and the bike is creeping forward with the clutch pulled in.
I'm thinking that the hydraulics wouldent be affected by the engine tempreture or am I missing somthing obvious
I'm not too worried how much this is going to cost, I just need it to be right

[zombie]

Hi Oily,
I would bleed the clutch while the bike is hot, at least that would strike the easy choice off the list and get the clutch working as good as it could be.

One thing to check with the clutch setting is that the master piston is returning fully, sometimes the setup is wrong (set too tight) and it doesn't return fully result is it works less and less as time goes by.

Hope that this helps
Zombie.

[tlracing]

A few other thoughts in random order of preference:

- Motul 300v is available in 'car' and 'bike' versions (I'm sure you'll have used the right one, but just 'box ticking' for certainty)
- Are you seeing any drop in the clutch reservoir level?
- Clutch springs getting too hot so not releasing properly? (Possible if the slave wasn't working before & it's allowed it to overheat?)
- Try re-bleeding when the drag is present - see if there's any improvement
- Check m/cylinder seals aren't being bypassed
- Sticking slave cylinder?

Cheers

[brian]

Hey oily, did you end up solving this issue. The clutch on my SB6 drags badly too. I've tested the master cylinder and itdoesn't bypass. I've changed the clutch fluid and bled the system. The clutch lever feels better now but the clutch still drags. The bike had been sitting unregistered for 3 years before i bought it, but i've put around 150 k's on it since i've had it.

I was thinking about maybe shimmimg the pushrod a little to see if that helps. Only other reason i can see is a warped disc maybe, but with low k's i thought this was unlikely.

Any ideas?

Cheers,
Brian
_________________
'99 DB4 #104, '96 SB6 #1165, '94 DB2 J #652, '99 DB4 #088, '08 VTX1800, '93 ZXR750R M1, '95 ZXR750, '95 ZXR750 Race Bike, '94 CBR400rr NC29 Race Bike, '94 CB250, '49 BSA C10 250, '61 BSA A10 650, '89 ZXR750, '91 Ducati 851

[Evilchicken0]

When the bikes are riden hard the hear creeps along the pushrod and then boils the fluid - or at least it did on mine.

When I first bought the bike it started creeping. I took the fairing off for the first time and the slave cylinder bolts were undone.

Because yous has stood I'd say the seals have probably perished a bit, I'd do the slave first then the master.
_________________
Don't read everything you believe

[Evilchicken0]

PS. You don't ned to drop the engine to bleed the slave it has a non return valve, just put a pipe on the nipple and pump away.

Unless mine's had an aftermarket nipple added
_________________
Don't read everything you believe

[brian]

Mine doesn't get worse as it heats up (like oily's did). Mine drags from cold and remains about the same. I don't think the slave is bypassing as it's not losing any fluid. I tested the master cylinder and it holds pressure. I have already flushed the system and changed the fluid. Took a while to bleed but i eventually got there. The lever does feel better but i haven't taken it for a ride yet as i ran out of time to put it back together.

I haven't tried to remove the slave cylinder yet but i recon it will go close to coming out without dropping the engine, anyone done this?

My slave has a standard bleed nipple, not a check valve type, but it was still no problem to bleed.

Cheers,
Brian
_________________
'99 DB4 #104, '96 SB6 #1165, '94 DB2 J #652, '99 DB4 #088, '08 VTX1800, '93 ZXR750R M1, '95 ZXR750, '95 ZXR750 Race Bike, '94 CBR400rr NC29 Race Bike, '94 CB250, '49 BSA C10 250, '61 BSA A10 650, '89 ZXR750, '91 Ducati 851

[Evilchicken0]

The bolts are quite long so they might touch the frame before they clear the housing.
I'd fit a speed bleed nipple if you do take the slave off, but ride it first.
_________________
Don't read everything you believe

[brian]

I took the bike for a good ride yesterday and the clutch still drags the same.

Yeah, i had another look evil, no chance of getting the slave off without dropping the engine.

I think i'll just have to bight the bullet and pull the engine and remove the discs and plates. Do you think it's worth changing the engine oil first. I have no idea what oil the previous owner used or how old it is for that matter..
_________________
'99 DB4 #104, '96 SB6 #1165, '94 DB2 J #652, '99 DB4 #088, '08 VTX1800, '93 ZXR750R M1, '95 ZXR750, '95 ZXR750 Race Bike, '94 CBR400rr NC29 Race Bike, '94 CB250, '49 BSA C10 250, '61 BSA A10 650, '89 ZXR750, '91 Ducati 851

[Evilchicken0]

I think it might be worth using an oil flush / cleaner in it before you drop the original oil.
You don't have to drop the motor completely you can swing it forward on the top mounts and get enough clearance.

Wrap the chain in a cloth so it doesn't scratch the swingarm, you need to take the back wheel out and so the chain is in front of the wheel spindle. You can't take the chain off the front sproket with the engine in place.
_________________
Don't read everything you believe

[oily]

[brian]

[brian]