I have has emulsified gearbox oil since rebuilding the engine and am about to fit new seals.
Am I right that the mechanical seal behind the impeller is what seals the water pump and there is no need to remove the complete clutch cover ??
1 Drain Coolant
2 remove the water pump cover
3 unscrew the impeller
4 replace the 2 seals, 1 fitting into the impeller and the other spring loaded seal fitting into the clutch cover.
5 refit the impeller and pump cover
6 fill with coolant
7 test for leaks job done.

Just checking that I am not missing something

I think you are correct from what I remember ....................... .

Have you had to keep topping up the coolant system?
Mike

I may have been losing a slight amount of coolant it is hard to say as the bike has been close to boiling a couple of times.

Its a bit ironic but they get really hot bursting a way through snow drifts.

Breather is well and truly sealed.
When I open the level screw after a short ride with fresh oil, grey stuff comes out and it is definitely emulsified when I change it at the end of a ride. (Ride means a full days trail riding through all sorts of stuff)

I'll fit the new seal and hopefully have clean oil next time.

I had the same problem on a gas gas trials bike but the pump was separate on that and could be pulled off with the cooling system full. It was then possible to see beads of coolant on the engine side of the pump.

Fingers crossed