I have trouble with my clutch sticking on. Its jammed solid at the moment, I think I'm going to have to dismantle it to free it off. I've owned the bike for 10 years and it has always done this if the bike is left for a couple of months. I changed the clutch and steels a year or so back and it cured it to start with but its now back to how it was again.

I'm beginning to think I may have water getting into the gearbox and rusting the plates. I change the oil every 6-12 months, but when I drain it, the oil always comes out very grey and murky. It looks like its got water in it some how and then emulsified. The oil has always come out like this since I owned the bike. The engine was rebuilt about 2000 miles ago and had a new water pump seal at the same time. The bike doesn't get through coolant, in fact I have never had to top it up.

Is there any other way water could be getting in there. Perhaps when its washed or riding through water?

Well, reading that report made me wince, { i change the oil every 6/12 months ]
Personally, I would change mine every 4 rides, especially if there's been puddles, or stream crossings.
Oil is hydroscopic [ absorbs water], and over that time frame will turn to an emulsion.
If it's only road work that's probably different.
Jet washing will get water in where it's not wanted.
Have you routed the breather at the top of the gearbox up into the airbox.
Buy cheaper mineral oil, but change it frequently.
Mike

I probably ride about once a month, if I'm lucky, so it probably gets changed every 6-10 rides. Every 4 rides sounds a little over kill, but maybe I'm wrong. In theory a 2T gearbox should have zero contamination, unlike a 4T (although mine is getting water in I think) or is that wrong?

The breather is routed into the airbox.

Drain it off after a couple of rides, if it still looks ok,put it back in again.
That'll soon show how quickly the oil is breaking down.
Mike

I do mine every couple of rides these days as I left it too long once (600 miles) and it killed the balancer shaft bearing.
If you are using the bike for laning or enduro it is getting worked hard. The clutch is being used a lot and will put particles into the oil. change every 200 miles max unless you are road riding of course?
There is only 700ml or so of oil in there being abused.

Okay, I think I will flush it out and change it on a more regular basis and see if thing improve.

Thanks Christian.

I use halfords own box oil so not too expensive.