800ss clutch slip probs
 

Not strictly DD but, as an 800ss has a wet clutch pretty similar to a 620s I thought this would be the place to ask.

I was practising at Croft the other day when towards the end of the day I thought I was detecting some mild clutch slip in the higher gears when winding it on out of the faster corners. It was a very hot day with the oil temp up around 140-150 degrees C.

The bike runs on 15w-50 semi-synth and has done two full days at the track including the day in question. I've not done any fast starts or race starts so, I would've expected better than this. I drained the oil today and it was absolutely minging - black. Again, that surprised me given that it has done about 200 miles. There was no debris in the oil or the strainer.

I'm racing the bike this coming weekend so, I don't want to get caught out. I have a spare clutch in a spare engine and I can always rob the one out of my 800 road bike as well but, I suspect I would face the same problem again.

Has anyone else experienced this with the 620s and what have you done to cure it?

TIA

can you put another clutch plate in.

any way just an idea havent had the problem myself

Had this on the 583/674 myself at Castle Combe last year - the clutch pack got absolutely toasted and the metal plates turned blue, as did most of the clutch inner.

Dr AK advised me to fit an extra plate, if I remember correctly, but as I'd broken two bones in my hand (and it was doing an impression of an over-inflated rubber glove at the time) he kindly took over and sorted it for me by replacing it with a spare clutch I had and sorting the pack. It never happened again after that.

Drop him a message as I'm sure he'll explain in more technical detail.

Thanks Antoyne. I will drop Al' a pm then.

Had some mild slip on the 620 early last season - as I think did quite a few others. Typical remedy is to insert a plain plate in the centre of the pack. Worked for me.

Or get a slipper clutch from Sigma!

I had this problem at Oulton Park last time out.

Bike had been fine on the trackday on the tuesday before, but it was a stupid hot day and the bike was hotter than a hot thing that is very very hot!

Anyway, the first 3 laps in SoT qualifying on the Saturday the clutch was slipping over 7,000 but eventually it went away and was fine for the rest of the day.

No idea what it was, but we thought that the plates may have glazed??? when the bike was running so hot on the trackday??? Not sure.

However, I'm glad you've mentioned it, coz I can remind Chass to have a look.

Hope you get yours sorted.