Weird clutch slipping situation!

Jdiddy313

Jdiddy313

Registered
2003 Hayabusa

BEFORE I GET STARTED!
I have replace the master cylinder and all new internals, new 2004 slave cylinder (yes it fits), fresh 5.1 brake fluid, replaced the sprocket cover with heavy duty bullet cover (to protect the pushrod and water pump in case of a chain break), new push rod, put in a new clutch kit and I am using the OEM recommended oil weight/type. I even use a mityvac to get the air out of the line.

Before it was slipping when warm.
Now it is still slipping when warm.

The weird thing is...... While the engine is still hot and slipping, I can pull over, open the bleeder screw on the slave cylinder, tighten it back then the clutch stop slipping for a while. Then I'll just have to repeat the process until I get to my destination.

HELP ME! WHAT IS WRONG!? :banghead:
 
To much fluid in the master cylinder? When brake fluid gets hot it expands, and if there is no place for it to expand to it will push on the rod causing the clutch to slip.
 
jermzfree said:
To much fluid in the master cylinder? When brake fluid gets hot it expands, and if there is no place for it to expand to it will push on the rod causing the clutch to slip.
Click to expand...

jermzfree, I think you are referring to the master cylinder RESERVOIR
That is one possible cause . . here is another possible cause,
The clutch slave cylinder piston may be sticking and not returning back to it's position where it has NO pressure applied to the push rod.
Question: When you open the bleed nipple, does fluid come out under pressure, or does fluid just seep out slowly?
There is a series of checks to go through to eliminate possible problems step by step.
 
Kiwi Rider said:
jermzfree, I think you are referring to the master cylinder RESERVOIR
That is one possible cause . . here is another possible cause,
The clutch slave cylinder piston may be sticking and not returning back to it's position where it has NO pressure applied to the push rod.
Question: When you open the bleed nipple, does fluid come out under pressure, or does fluid just seep out slowly?
There is a series of checks to go through to eliminate possible problems step by step.
Click to expand...

When I open the bleeder screw the fluid shoots out, then I tighten it back and continue riding. Clutch stops slipping for a while.
 
Jdiddy313 said:
When I open the bleeder screw the fluid shoots out, then I tighten it back and continue riding. Clutch stops slipping for a while.
Click to expand...
Ok, well that's the reason why it's slipping isn't it? Fluid pressure actuating the push rod and making the clutch plates separate.
Now, the question is, what is causing the fluid pressure . . .
Start at the slave cylinder . . you said you replaced it with a new one and a new billet cover/housing for the slave.
Put the original cover and slave back on and bleed it up, if that fixes the problem you have to strip and check that new slave cyl you fitted.
If it's still slipping, put the old master cyl back on, if that fixes it the new master cyl has a fault (but I doubt it, I reckon it will be a slave cyl problem)

Hey, did you check the fluid level in the reservoir? If it is too full, it will cause problems too . . .
 
Kiwi Rider said:
Ok, well that's the reason why it's slipping isn't it? Fluid pressure actuating the push rod and making the clutch plates separate.
Now, the question is, what is causing the fluid pressure . . .
Start at the slave cylinder . . you said you replaced it with a new one and a new billet cover/housing for the slave.
Put the original cover and slave back on and bleed it up, if that fixes the problem you have to strip and check that new slave cyl you fitted.
If it's still slipping, put the old master cyl back on, if that fixes it the new master cyl has a fault (but I doubt it, I reckon it will be a slave cyl problem)

Hey, did you check the fluid level in the reservoir? If it is too full, it will cause problems too . . .
Click to expand...

The old slave cylinder was BAD, cylinder wall was too dirty for it to even hold pressure good. I use the 2004 slave cylinder because it was fitted with a rubber nipple that prevents dirt from getting in the cylinder walls.

The new bullet cover is so nice, I hope I don't have to get rid of it.

I think it may have too much fluid in it. I literally turned the handlebars all the way to the right and filled up the master cylinder all the way up and replaced the cap and screws. :banghead:
 
jermzfree said:
Well that would explain it. It needs to be at the full mark on the reservoir. Make sure you didn't overfill your BRAKE master cylinder reservoir as well. That would be bad!
Click to expand...

I for sure over filled the clutch Master cylinder. I have not touched the brakes master cylinder YET.

NOW.....where is the "full mark"?
 
Kiwi Rider said:
OK. . . now we are getting somewhere!
When filling it, only go HALF way up the sight glass with the reservoir in a LEVEL position. Easy peasy.
Same goes for the brake reservoir, NEVER overfill the reservoir.
Click to expand...

Took fluid out of the master cylinder ✓
Busa rides great! Had rode for 45 mins to an hour, kind of hard too. Everything was good, I did get a small bleep of slippage once on the freeway but that was it........

UNTIL I get stuck in traffic and the bike gets really hot. Then it starts slipping to the point of barely moving forward. But it never fails that once I pull over and open that beelder screw, the clutch is back snapping like it's brand new.

Question:
Do you think it is necessary for me to put some heavier clutch springs on?

Maybe the new OEM ones just suck!
 
You are using dot 4 brake fluid right? And not old fluid thats been sitting around the garage open for a while either?
 
Jdiddy313 said:
What do you guys think about getting heavier clutch springs would that make a difference?
Click to expand...
Well, the actual problem is that there is fluid pressure building up against slave piston and in turn, the push rod,.
I mean, you could replace the springs, but you are not addressing the real issue here.
Did you drop the fluid level in the m/cyl reservoir down to half way in the sight glass?
If it was me, I would just strip all the components down, inspect everything, and reassemble it all, basically just start over with it.
 
Jdiddy313 said:
What do you guys think about getting heavier clutch springs would that make a difference?
Click to expand...

Not a bad idea to inspect the clutch and components. But don't upgrade the clutch springs as a band-aid fix. First you would have to reinforce the slave cylinder to handle the extra pressure. Second your left hand would get super soar from a super stiff clutch handle, and third your clutch might still be slipping without you knowing it which can lead to clutch fiber filaments building up in the oil pickup return screen. and ultimately engine failure. IF you want to upgrade or change a component, I heard of a cable operated clutch setup for the Hayabusa. Kind of a simple old school fix but less hassle too.
 
jermzfree said:
Not a bad idea to inspect the clutch and components. But don't upgrade the clutch springs as a band-aid fix. First you would have to reinforce the slave cylinder to handle the extra pressure. Second your left hand would get super soar from a super stiff clutch handle, and third your clutch might still be slipping without you knowing it which can lead to clutch fiber filaments building up in the oil pickup return screen. and ultimately engine failure. IF you want to upgrade or change a component, I heard of a cable operated clutch setup for the Hayabusa. Kind of a simple old school fix but less hassle too.
Click to expand...
Tell us more bro, sounds awesome!
 
jermzfree said:
Not a bad idea to inspect the clutch and components. But don't upgrade the clutch springs as a band-aid fix. First you would have to reinforce the slave cylinder to handle the extra pressure. Second your left hand would get super soar from a super stiff clutch handle, and third your clutch might still be slipping without you knowing it which can lead to clutch fiber filaments building up in the oil pickup return screen. and ultimately engine failure. IF you want to upgrade or change a component, I heard of a cable operated clutch setup for the Hayabusa. Kind of a simple old school fix but less hassle too.
Click to expand...
I like old school fixes
 
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