Clutch slipping - friction plates or oil?

Questions regarding the DR800

Clutch slipping - friction plates or oil?

Postby Scuzi » Tue Jul 03, 2018 9:54 pm

I’ve noticed lately that under heavy load the clutch is slipping. It seems to be worse when the engine is warmer although that could just be in my mind. Especially noticeable on the motorway in 5th at 70mph (5000rpm), if I roll on for an overtake it slips for a bit up to about 6500rpm then catches itself.

Over the winter I changed the oil for JASO MA wet clutch spec synthetic, Gulf Oil brand. Is Clutch slip more likely with this oil in warmer temperatures or am I looking at replacing the friction plates? Thanks.
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Re: Clutch slipping - friction plates or oil?

Postby BigBob » Wed Jul 04, 2018 8:22 am

Usually when we get asked questions relating to clutch problems, it`s because the cable is starting to seize in it`s sheath and the answer is to take it off and get plenty of lube down it to free it up. Occasionally it`s just because the cable is badly adjusted.
In this case you are using the wrong oil. Your fully synthetic oil you are using is for the latest high revving bikes with lots of power and have plain bearing crankshafts and much tighter tolerances.
When the Big came out in 87 semi synthetic oil had just come out and was for Gixxers etc, whereas we used plain mineral oil as the bike was low revving and had a roller bearing crank.
I used a good quality 10/40 car mineral oil in my Bigs from 88 until quite recently as it`s being discontinued. I now use car based semi synth, and no, I`ve never had clutch slip.
I`ve done some big mileages in that time and gone round the clock with no signs of wear or oil usage at oil.
The one time I used fully synthetic I got clutch slip and the oil level dropped alarmingly so it must have been burning off very quickly.
It sounds counterintuitive but your oil is just far too good for the bike and you need to change to something more agricultural ;)
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Re: Clutch slipping - friction plates or oil?

Postby Deano » Wed Jul 04, 2018 3:28 pm

I have my wife's permission to keep breathing!!
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