Having removed the foot rest points and auto advance unit. The primary drive cover was persuaded to come of with absolutely no brute force and applied ignorance.
Oil pump easily removed but dismantling the pump was a different matter it was only just possible to turn it with a spanner on the nut that holds the drive pinion on. When the four screws in the pump were removed it would not come apart. Application of brute force to the slightly proud lugs on the top of the pump eventually got it apart. However the driven gear was very tight in the casting, heat and copper jaws in the vice did the job.The pinion measures 10.99mm with my best freshly calibrated micrometer. I still need to get the driving pinion off the shaft It is very tight.
Is it left handed thread?
How much tension do I need to put on the kick start return spring?
Also I didn't take enough notice with the auto advance unit, so a £ to a pinch off sh-t when it goes back together I will have the timing 180' out!!
One other question is the nozel on the oil pump body that transfers oil to the primary drive case cover supplied with the new pump castings and is the cone in the drive case spring loaded to make the seal to the pump body oil tight?