Help mushy clutch ONLY after hard pass

[AsleepAtTheTree]

This is so weird, not even sure if this is a common problem or not for ANY bike

Clutch steels and fibers went out, bought new oem kit, changed them out, slave cylinder started leaking shortly after, bought rebuild kit for both master and slave, changed them out, took forever(a week) to bleed and get pressure(tried multiple methods) ended up filling the slave till the piston was almost out the housing, ss line and slave with syringe through bleed screw while its off the pushrod, stuck it back on and bled it through the upper ss line on the master....finally got presurre...ehhhh

Road it for a day, jus cruising around
No problems

Brother calls me out on his 14r, we make a pass...i lose lol....get to the end of the street
No pressure

So of coarse im thinking, well i jus rebuilt the clutch n all, maybe i didn't bleed it all the way
Pump, bleed
Pump, bleed
Pump, bleed some more...pressure is back

Make another pass...clutch is mush again
No leaks
Pump bleed again, again and again...presure

Now heres thw weird part, ridw back home jus cruising, no problem, ride it the rest of the week jus cruising, no problem

But...

Make Another hard full throttle pass
Instant Mushy clutch again smh

What the hell is going on man smh!!!!

 

[AsleepAtTheTree]

Oh and when the clutch goes mushy coming off a full throttle pass, bike wants to die bc the plates are engaging

 

[Berlin Germany]

@AsleepAtTheTree

might be simple
did you put in last friction plate (#10) one tooth over (lh/rh) than all others?

this fiche above is only an example - #10 must be put in that way at all busa ´99-´20.
pic taken of gen2 manual - page 5C-19 (or -18 or -20) left side

if not, the clutch doesn´t work correctly - it tends to slip/slide very strongly .

i have technically no clue why , but that's how our experiences are (german forum / board).

 

[AsleepAtTheTree]

Will have to check this out to be sure...honestly

But what i did was put everything back in the same order i took them out...

Was hoping i wouldnt have to go into the clutch again but looks like its leaning more to be the issue

Its the only other thing i havent checked

 

[Berlin Germany]

(...)Its the only other thing i havent checked

please give info what you found (out) ;-)

 

[AsleepAtTheTree]

Will do

 

[Mr Brown]

Look at the slave cover while someone's squeezing the clutch lever. May be cracked.

 

[SSGT_B]

Even though you rebuilt the MC/ fluid could still bypass the seals. I had a similar issue with the brake MC. I would however look for a cracked slave as well.

 

[Berlin Germany]

@SSGT_B

hmmmmmmmmmm

the slave itself shall crack?

can´t believe this.

the only thing that may crack is the sprocket cover where the slave is screwed in.
but this only
when you´re using stronger springs.
we never found this with standard springs.

what i already 3 times found is a slave´s cylinder with inside washouts in the area where the seal is working.
even when it wasn´t dripping yet the clutch felt a bit spongy
bad luck - a new complete clutch slave then is unavoidalbe.
makes at the gen1 ~ 84 € (gen2 ~ 80 €) + 0,5 l dot4 (or 5.1) and 1-1,5 h time for entire replacement.

 

[Mr Brown]

@SSGT_B

hmmmmmmmmmm

the slave itself shall crack?

can´t believe this.

the only thing that may crack is the sprocket cover where the slave is screwed in.
but this only
when you´re using stronger springs.
we never found this with standard springs.

what i already 3 times found is a slave´s cylinder with inside washouts in the area where the seal is working.
even when it wasn´t dripping yet the clutch felt a bit spongy
bad luck - a new complete clutch slave then is unavoidalbe.
makes at the gen1 ~ 84 € (gen2 ~ 80 €) + 0,5 l dot4 (or 5.1) and 1-1,5 h time for entire replacement.

I know you mean well, but your constant stating "it hasn't happened to me so it can't happen" is not helpful. Cracked covers can and do occur with stock springs if you launch hard under a heavy load.
There are many members here who have years of experience with using these bikes in ways that you don't, and we know what the weak points are when they are used that way.

 

[AsleepAtTheTree]

Been working nights all week, haven't had a chance yet to have a look....

Gonna pull it out tomorrow morning and have a look guys, bear with me here plz

I appreciate all the help and advice...thanks

 

[Berlin Germany]

I know you mean well, but your constant stating "it hasn't happened to me so it can't happen" is not helpful. (...)

I want to make it clear once and for all.

if! i give tips / advices, then they apply to normal and standard motorcycles - here hayabusa.

i have absolutely no clue about the use for racing purposes and so i hold myself back completely and keep my mouth shut.

if someone is using a busa on the racetrack (e.g. 1/4 mile or so), he/she should write this down in a very clear way in the question,
e.g. used on street / used on racetrack

if this is not explicitly mentioned, I still generally assume that every technical question relates to normal road operation.

and by the way - what might be the percentage of racers out of the total number of haya owners in usa / in this forum?
around 5% or even less?

at the end :
what ever problems may come up with a busa on a racetrack, it is "nice" to read (for my knowledge base) but never a point of real interest for me.

a broken / cracked sprocket cover at a normal ! used gen1 busa with original ! standard ! clutch springs ?
i never heard of - in the 12 years now owning a ´00 busa - in our german forum with over 1,200 members.
at least I don't remember it .

 

[Mr Brown]

OP talks about making passes. This means he was drag racing. Maybe not on a strip, in an event, but the bike was being used in that way. You gotta read...
I don't know what the percentage of ownership is who use their bikes like this, but a lot of people do, at least sometimes.

I'm going to say this as nicely as I can, because I do think you mean well: If you don't know something, ask. Stop assuming things and countering other people's advice, It makes your responses unhelpful. Doesn't matter wether or not you have heard of a problem, some of us have been doing this a while now, and know things you don't. Some of the Hayabusa specific drag racing knowledge on this board goes back 20 years. We can all learn from each other, and you've contributed to that. (Your engine stand for example). You obviously have experience and want to share it with the group and that's valuable, just stop trying so hard....

 

[SSGT_B]

ie:

 

[Mr Brown]

ie:

Just not mushy pie....

 

[SSGT_B]

Just not mushy pie....

Right!!! Now if the admins would make me a pie emoji!! Lol

 

[AsleepAtTheTree]

Welp...really gonna hate even typing this

Went out to the bike this morn to start tearing her down, i did the obvious checks again jus to be sure like pulling the clutch and looking for flex of the sprocket cover and leaks, kept squeezing the clutch lever and noticed a squishy wet sound

And boy OH boy.........you guessed it

A LEAK


HOW in the hell i missed this after check after check after check...idk

But its definetly leaking from the slave cylinder, smelled and taste like fluid and all lol, once again, i pumped and bled, pumped and bled, pressure and working clutch again confirming my issue and not being clutch plates or internal parts...I even made a few 60ft launches lol

I feel so stupid...lets hope a new oem slave cylinder makes me happy again lol....THANKS EVERYONE

 

[AsleepAtTheTree]