As this engine may have suffered from lack of oil distribution it needed a full investigation.
To get to it you have to remove the complete clutch first. In doing so I found that one of the six bolt holes in the basket had threaded slightly. I had the one from the spare engine to replace it, so I can repair the thread at a later date. The clutch plates themselves were in good condition so could be used again.
I made good progress working on the two engines simultaneously, for reference and to use whichever parts were in better condition. I had a look at the oil pump of the spare engine and it was very much as bad, if not worse. The oil pump shaft showed more signs of wear so I stayed with the original.
It was quite clear that there were score marks on the rotors, housing and cover so I order a complete pump kit.
I wasn’t impressed by the finish quality of this new oil pump. All of the important surfaces were good so I used it anyway. Lubed each piece and squirted more over the rotors when assembled in place.
There was a big difference in resistance when I turned the gear as against before with the old one.
The oil pump kit had only two screws/bolts with it when I expected three. The reason was that there are two versions available. The earlier models had a total of three securing screws whilst the later models had five. So this kit was adding only the two extra shorter ones required to convert from three to five. Two of the original longer screws had slightly mangled heads so I replaced those from the spare engine. Later versions also came with an extra gasket. Although I didn’t use it.
Apart from one engine used a 3 screw pump housing and the other a 5, I did notice two other differences. The type of bearings used and that the later engine does not have the alignment dot punched on the points gear, so it was difficult to see.
Next was the timing cam chain which looked fine until comparing it with a new one.
I’ve had the chain for at least 18 years so I wasn’t sure it would be OK. Packaging was still intact so no moisture and no rust, so I was a happy bunny.
I lubed it.
