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Discussion Starter #1
Owned the F4 1078 from 2009 for two years, 10k miles on clock. Ridden fast but sensibly, no track days or wheelies. Done 3k miles myself, serviced last summer when valve gaps and other items were checked.

Rode fine since 2015. Serviced last May, incl oil change. Went to Isle of Man for long weekend, with no problems, in July. Changed the brake and clutch levers end of July. End of August returned from a shortish ride (no problems outbound) and got a slight slip in top gear at 4000rpm, seemed to go away and then appear intermittently since, some test rides I can floor the throttle and no problem whilst others see slipping and rev rises. May be ambient temperature related but not firm. Tonight went out (hot day) and sensed slipping straight away. Whereas normally 60mph at 4000rpm in top I was getting 45mph. Aborted ride after 10 miles and refuelled. On heading back had virtually no drive through the clutch. Changed the clutch on my 916 myself so I can visualise the system. Managed to limp home as it gradually improved a bit but lucky!

Only concerns with clutch had been that it felt 'grabby' when cold and you engage first gear (felt a minor jump and if you manually wheeled it backwards to manoeuvre it felt like you were working against the engine slightly). You felt it was slightly engaged even with lever held fully in. However this would be the opposite of the slipping problem where the clutch just doesn't transmit power even when fully 'engaged' with lever untouched.

Anyone got any ideas? It is a slipper clutch but that is irrelevant to this. Do hydraulics maybe just need bleeding, could that make the pushrod disengage the drive? What about the slave cylinder and pushrod system itself? It's easy to blame the clutch pack but it has only 10k miles of fairly sensible riding. Forum mentions springs, how likely is that? I have a local Italian bike specialist about to look at it but desperate to know what experiences people have had. It just doesn't feel like it's going to be simply a worn out plate pack.
 

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Check the adjustment on your aftermarket clutch lever.
Have seen these causing issues in the past.
 

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?

Put the stock levers​ back on.......
Then give the clutch a thorough bleed.....

Bet that fixes it!

sounds like the pushrod is too long and not uncovering the return port....

:wink2:
 

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Discussion Starter #4
Right! I think this has sorted it. My suspicions were right, it didn't make sense given the timing of the issue and the intermittent nature etc... Thanks so much to the forum responders for giving me the confidence to take another look. Couldn't get away from the problems only starting since the levers were changed. Took the bike for about 6 miles, this the morning after the problem nearly left me stranded with no power. Not too bad initially, then the slipping starts in top and other gears under acceleration, not as bad as night before but still there.

Found the original stock lever in the garage, it was snapped but useable (from a stationary topple over last July) so dismantled the new lever. The brass ferrule which makes contact with the protruding link to the hydraulics was solid in the lever, managed to get it out with some force from a screwdriver and fitted it into the old lever. Thinking about it, that was the problem there and then, the ferrule was not mobile in the recess of the lever. With the old lever having free play for the ferrule the next 6 mile ride saw no issues and the engine power transmission just 'felt' better. No sign of slip.

So the acid test. Refitted the new lever after a little lube from some Wurth dry chain lube. Looking at the new lever, the recess at the back had seen the black paint rubbed away so there was clearly friction going on. Fitted the new lever and did the same 6 mile ride, using some of the engine's performance as a real test. No problems.

Obviously needs monitoring but looks like that's it, rather than dismantling the clutch and buying new bits which wouldn't be cheap. Gut feel is often right, it just didn't add up.

Thanks again guys, hope this string helps someone else too!:smile2:
 

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Another victim of "Whatever was done last is the cause of the new issue..."
 

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Discussion Starter #6
Update:

Took it to the Isle of Man after a couple of trouble free warm ups. Packed all the minor tools needed to dismantle the lever if needed. Couple of rides in, started getting the same symptoms. Dismantled the lever and reassembled after freeing the brass ferrule in the lever and all was OK.

Bike stands outside when we're away, a bit of damp here and there probably doesn't help. On way home, coming out of the Mersey tunnel, it slipped badly again. Dismantled the lever and the contact pin which transmits the pressure from the lever to the hydraulic line itself came out (it seems like it is meant to). It had a lot of grease on, it went back in OK but for the clutch to slip this pin must be being pushed in or maintaining positive pressure even when the lever is withdrawn. Could it be this pin that's at fault do we think, or is it still the lever/brass ferrule. The clutch was OK to get me home, I have now emery clothed the ferrule to smooth it out a bit, but the pin is now making me wonder. Should it have all that gunge/grease on it or should it be dry so it moves more freely?

Any thoughts welcome. In the meantime, my downshift return spring has failed (see another thread!) so I need to fix that first.
 

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I think that dried grease can cause the pin to stick in the "actuated" position.

Were it me, I would clean the pin and the recess. Then I would lubricate with a dry lubricant like graphite.
 

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Discussion Starter #9
It went in to be looked at, view was that the aftermarket lever dimensions kept more pressure on the hydraulics when disengaged than the stock system so the pressure wasn't able to fully rebalance after activating the clutch. As a result the pressure stayed in the system to a degree and eventually started to activate the clutch rod, causing slippage. Overhauled the actuation system and shortened the activation pin by a couple of mm as the lever was not allowing it to withdraw fully. Working OK now but still monitoring it as this was a gradual decline in the past, with the slippage coming into play as time passed.
 

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Try and get some original levers and put them on as has been mentioned.
I have the the original levers on my 1078 and never had an issue with the clutch.
 
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