Technical Question for anyone with the possible answer....

[jfbarron]

Hi All,

This question has to do with clutches and engines.

I own a 2005 R1150RA with 18K kilometres on it now. Dealer serviced since new.

I added some dot 4 clutch fluid at about 15 K because the clutch was feeling funny and it helped the action. At 16.5K I took it to my dealer for new tires, ABS bleed and they also did the clutch fluid as well. Everything seemed fine.

Yesterday I was zooming along our notorious 401 highway in top gear at 4500 RPM when I heard an increase in engine noise from the left side of the bike and the power dropped off briefly-for maybe 1.5 seconds. Then all was OK.

It seemed like the clutch slipped briefly but the noise seemed to come from the left jug area. I was not looking at the rev counter so I have no idea if it went up or not.

I plan on taking it to the dealer for the 20K inspection in about 2 weeks. Does anyone have recommendations based on their experiences?

[GTR350cc]

Partial help at best...

Noises can be coming from anywhere. At speed, with a helmet it is nearly impossible to accurately determine where the noise originated. So don't let that be your only guide to diagnosis.

Next, these transmissions have a reported incidence of occasionally slipping out of high gear at speed and sometimes actually dropping into the next lower gear. Has to do with worn, shift dogs (I think) and your report sounds more like that than a slipping clutch. (Dean and Rob know the real deal on this one.)

Next2, a nearly worn main seal can let fluid past and contaminate the clutch. It is conceiveable that a small, early seepage would have an intermittant effect, i.e. slipped clutch; then go away as the fluid was burned up. Any noticeable odors? Any seeps/weeps that leave any stains on the undercarriage?

I am woefully under educated and hope the smarter guys chime in soon.

Best of luck.

[baltm604]

If the clutch is gone, or if you have a leak and therefore a wet clutch, the engine will rev underload but not accelerate. It will be really noticeable in upper gears.

If you pull the starter, you can check the flywheel and see if it is wet.

Although our clutch is good for 50k+, riding style and environment can kill a clutch in 15K. I unfortunately know this from experience.

Bill

[CycleRob]

I was zooming along our notorious 401 highway in top gear at 4500 RPM when I heard an increase in engine noise from the left side of the bike and the power dropped off briefly-for maybe 1.5 seconds. Then all was OK.

OK. So you were cruising along at 90mph in 6th gear and the left cylinder cut out for less than 2 seconds. Then all was OK. Those symptoms tell me that something like a cornflake sized sheet of carbon got red hot, flaked off and blew out the exhaust. During that time, about 1.5 seconds of power pulses in that cylinder can misfire when the carbon dust cloud bridges and fouls the sparkplug gap and/or prevents the exhaust valve from sealing in the cylinder pressure (=misfire). It's also possible, and very likely, that the left cylinder was detonating (the loud pinging noises) and misfired until you backed off the throttle. A sustained Summer heat headwind, substandard gasoline and a steep uphill could easily cause your malfunction. It would be made worse if it was really hot out and you were drafting vehicles in front of you.

The quick recovery to normal after a misfire was my #1 clue. That, and running in 6th gear at 4,500rpm (=90mph) heats up the combustion chamber much higher than normal riding and will create temperatures and pressures that "blow the carbon out".

[jfbarron]

Thanks guys! CycleRob's answer exactly described the situation and conditions.