Clutch question obviously because I have a problem :(

Sounds like a seal on the system passing very slightly and allowing the pressure to be lost at the slave piston which pushes against the clutch rod. Fluid hydraulics (brake system) will always hold pressure forever as long as the seals hold. The black discolouring sounds like you make have chain lube contamination getting into the slave cylinder seal which then discolours your nice fresh fluid. If it were me I would re-kit the slave cylinder first or replace with an upgrade, as they get hammered in their location.

i wud say its from engine oil passing through the small pushrod seal on the slave thats getting into the clutch system thats making it black .i know some of you guys blame the rubbers in the master thats the problem but if that was the case then why does`nt the brake fluid go the same way so soon after bleeding ? but who am i to say only having 25 odd years in the motor trade 19 of them building gearboxes ,im sure the problem is the small seal in the slave thats the main cause :remeber the engine has some pressure in the inside which could push oil past the small seal when its hot or when worn .but dont say i told you so as i could be wrong lol

The black fluid is caused by aluminium contaminiation from the M/C contaminating the fluid. Rub bare aluminium with a cloth and it will come off black.

It does it on the clutch more than the brake because the stroke of the clutch is considerably more than the brake. so you have twice as much piston travel and the fluid is much hotter so brekks down more quickly. It can't be oil as not only would it have to pass out of the pushrod seal and travel along the pushrod, it would also have to pass through the slave seals also. If oil could remotely get in through a big enough gap in the seal then clutch fluid would be coming out much quicker as it's under pressure.

To answer your question of the clutch going off when hot if your not losing fluid = air. Air expands when hot so your at a standstill and the engine is getting warmer, heating the slave and fluid which causes the tiny air bubbles in it to expand losing your clutch pressure. You can compress air but not fluid. My Ducati has the same issue on the rear brake with the fluid going black as well as the clutch (long stroke M/C). Did it from new as has both Rsv's.

The fluid colour is not an issue other than appearance wise.

Top man!!

well that sound much better than my answer spoonz ,but at least mine was better than the chain lube contamination guy lol dont you think lol..:thumbup: i did say i could be wrong did`n I

mad biff said:

well that sound much better than my answer spoonz ,but at least mine was better than the chain lube contamination guy lol dont you think lol..:thumbup: i did say i could be wrong did`n I

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I'm just an old (ish) fart who has been down this road before with air in the M/C and black fluid. It's a Brembo thing. Any bike that runs Brembo hydraulic stuff is prone to black fluid and air in the clutch system has long been an achilles heal for Ducati and Aprilia. My 04 Factory had 3 revisons of clutch M/C under warranty and still had an air issue. Hence the v4 went cable.

The stator and slave area on the v60 is one of the hottest parts of the crankcases and the fluid and seals get a tough time. Back in 04 we did some testing with a laser temp gauge for an AF1 thread and the slave on a stock bike ran at 106 degress cent at normal idle.

Dot 4 for example has a max operating temp of 160 ish (5.1 -180 ish) and a normal working life of 48 months at average temps beofre it starts deteriorating. Running at 106 is somewhat above average imo and gonna cook it much quicker than 48 months. Unlike your front brake which gets hot and cold in short cycles as you use the brake, the clutch system is hot contantly when the bike is running to some degree.