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[Dennis C]

Has the bike been stood with oil in it while the top end was rebuilt?, if so possibly it has wet sumped.

The return oil should cointain air bubbles as the scavenge pump is bigger than the feed, have you tried draining the sump to see if it has excess oil in it?.

[Isettaman]

Just off out to the garage to check on the oil level in the crankcase and then the return flow and rocker feed.

Will report back.

[Isettaman]

I think I might have found the problem. I unscrewed the drain plug in the crankcase bottom, where, I believe the return oil goes up and 1 3/4 litres of oil drained out. This leads me to think that there must be a problem with the crankcase seal between the oil tank and the crankcase chamber. I have taken a photo but cannot see a way to upload it here just to make sure I have the correct plug. On my engine, there is one right at the front of the crankcase, another in the centre and the third is on the side, veritcally below the filler cap. It it the centre one I have removed, is that correct?
How do I upload pictures?
Dave

[Dennis C]

Not 100% sure which is the crankcase drain on this engine, but if your oil tank is still full I guess you got the correct one if not you just drained the tank.

[Isettaman]

This might be right for a picture?

[Isettaman]

Oooh! A Picture

The middle one is the one I got the 1 3/4 ltrs out of.

When I unscrewed the rear one on the side of the crankcase, I just got a dribble out.

Looks like an engine out job again!

Dave

[PeteF]

1 3/4 litres!!! I think you just drained the tank.
Shine a torch up the one you removed and look down the oil filler. It should be the front one to drain the crankcase.

[Isettaman]

Shone the torch but couldn't see any light through the filler cap but you are correct that the centre plug empties the supply tank.
I removed the front plug and quite a lot of oil came out, clearly in excess of the 30cc stated in the technical notes.
I will replace the oil in the tank and then see how the pump performs.

[Isettaman]

Replaced the oil in the tank and have run the engine for 10 - 15 mins. On draining the crankcase, 400ml of oil came out against the reccomended 300ml. This seems rather a lot of extra oil for a short period of running and indicates to me that the return pump may not be functioning as it should. Also, I noted that the oil from the return pipe into the tank was quite steady at first but then reduced to a drip as the engine warmed up which I feel indicates an issue with the return pump. I have ordered a new pump body and plunger and will see if that improves the situation.

[PeteF]

I would run it for a lot longer on the road to really see what is going on.