Cloudy clutch fluid

Just changed my clutch fluid on the weekend - it was milky black. I know it's not peculiar to my bike - the dealer's demo busa has the same problem (and I remember some posts on this subject in this forum a while back).
Has anyone figured out what's causing this problem?

Service Manager told me it is caused from the extreme temp the fluid see's being that close to the motor. The brown is a chemical reaction caused by condensation in the line cuased from the extreme heat and the cooling after the motor is shut down.

I asked and this was the answer. ???
mine did same thing,change fluid to motul600 synthetic.just be sure to flush old fluid good,you can't mix the two.the motul is supposed to be the best,it'll stand up to 595 degrees.
On a Bus,

To replace the clutch fluid, I did the following:

- remove LHS fairing lower
- remove coolant resevoir & place to one side
- connect bleed hose to bleed nipple on top of clutch release mechanism.
- remove clutch fluid resevoir outer & inner covers as well as rubber boot. (take care you don't get clutch fluid *anywhere* - if you do wash immediately with water)
- bleed clutch until resevoir nearly empty
- top up with fresh fluid
- continue to bleed & top up until all residue is gone (takes about 3-4 top-up's)
- put everything back together.

The new master cyl resevoirs are great to work with - they have good sealing systems and they don't squirt fluid everywhere when you're bleeding them. I'm going to have to disassemble the master cyl & resevoir someday, though - there's still some crud stuck to the sight glass on the resevoir.

Hope this helps,

I'm not real convinced about the idea of heat causing the cloudy clutch fluid. If you think about it, you engine temp shouldn't get above 100-120C (212-248F). Brake fluid is designed to work near brake disks, which get a hell of alot hotter. It's got to be a contaminant of some sort. I suspect oil through a seal in the clutch mechanism. One day when I get p.issed off enough about it I'll pull it apart and have a look.
Have those of you who have changed to super-duper brake fluid noticed any further cloudiness develop?

mine is very dark milky black. I flushed it completely by disconnecting the line @ the mechinism. It was clear for maybe a week? back to black again. idfk. i used fully synthetic dot 4
the cross head screws can be a ***** to undo on the clutch master cylinder, remove the clear perspex screen, to get better access, so impact philips driver to release them..the screw heads are soft as butter, at first chance you have change to allen head screws.... whats the difference the dot 2, 3, etc brake fluid... got glycol it works am i missing something usually am...

My clutch completey fails to engage after being laid up ... it works after bit coaxing and tinkering bleeding and tapping the lucky spot with a hammer ;p
ok the lower the dot number the lower the boiling point but i am not planning to cook with this stuff...

at least this bike lot easier then ducati or harley to fix .. god i hate my harley ;p


Evil Demon Busa Rider
Donating Member
Temperature is not what causes the darkness in the fluid. Never have figured it out but it's a common occurrence. I just think the system isn't quite sealed and allows particulates into the fluid but that's only a theory.


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