Thanks Mark.  I found one 21mm x 4mm in the UK.  I will hold off on the welch dish plug and wait for this one to arrive.

I will report back if suitable.

Link.

www.bearing-king.co.uk/bearing/ec21x4-en...ide-x-4mm-wide/24791

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Replied By  MarkT  On Topic  Oil Pump End Cap?
I was wrong.  The 21mm x 5mm shaft end cap is not close, it's exactly what Yamaha used. 


Good detective work.  Perhaps there should be a sticky where useful stuff like this can be kept.

I guess there's no pressure involved as pressure is created in the plunger shaft thingy, if ya call it pressure to send the oil up to the cylinder.

Weird, Yamaha listed the oil seal for when the priming wheel was fitted there, but not the blanking plug when it was removed on the later models.

Anyway, looks like you've got it sorted between you!