I think that you will find that the helicaly cut plastic water pump gear is driven by the helically cut primary gear on the end of the crankshaft.
The straight cut gearbox oil pump gear is driven off the small straight cut gear on the back of the clutch.
It is the two O-rings behind this straight cut gearbox oil pump gear that you are talking about and I believe, without checking, that they are identical to the O-ring used under the MC21 two stroke oil pump. The 8mm x 1.5mm O-ring referred to above. 91307-283-000
It seems that people quite commonly refer to the gearbox oil pump gear as the water pump drive gear, but I think this is quite incorrect.
Sorry if I sound a bit anal here. But just trying to be correct.
Does anybody wish to agree with me on this? The gearbox oil pump gear thing, NOT the being anal thing
Well OK,.. both.
For a bit of clarity on this, see the 4th to last picture here.
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