KH Over Oiling - a different question

[SteveHands]

No Paul, the one-way valve in the breather hasn't solved the issue, but it has reduced it a bit.

Since my last posting I have modified the rocker oil feed so that it's now tee'd off the return to the tank. I put a small restriction in the tank side of the T-Piece to ensure flow to the rockers. I've done about 170 miles with that setup and the rockers haven't seized so I guess that's working. That also didn't reduce the smokiness.

I'm now wondering if I'm getting oil pooling in the left side crankcase. Some long time ago the left case was damaged, possibly by a broken rod punching through or maybe an accident. Wasn't obvious at first because the repair is so good, but I finally noticed it when I realised why it had a gasket between the halves - because the case had been re-faced following repair, and the gasket it there to correct the spacing.

I'm thinking that if the internal shape of the case is now distorted and retaining a pool of oil, that could be picked up by the flywheel and thrown up the bore. Or maybe the clearance between flywheel and case is now too small which could cause the same thing. I know it's fairly close anyway. I also know that many wet-sump machines have a baffle plate in the sump to prevent oil surge being picked up by the crank.

Final thing - I'm going to try running without the mesh box around the pump. It's been suggested that the ultra-fine mesh is restricting oil flow to the return side of the pump. I have had a similar thing in a race bike where the pattern-part filter mesh on the oil tank pickup was so fine that once the oil was aerated by the return churn it would just suck the air bubbles through and not the oil and destroy the crank. Took three cranks to spot that one and the problem went away when I cut the mesh off. Thoughts?

[Paul Slootheer]

Sorry to hear you are still struggling with the oil problem. I guess you allready know KH pumps are notorious for wet sumping? The pump on its own looks to work ok, so this can not be the problem. You also altered oil flow upstairs. What more can you do? I can’t imagine distortion of the cases will create this specific problem. I know it’s a lot of work, but did you checked the piston rings for the gaps/damage?

[nevhunter]

The scavenge Pump should have about 2 times the capacity of the supply one. That should ensure that Bubbles are returned soon after starting the Motor. The ARIEL 500 twin has a fairly high rate of Oil flow which is very evident with the filler lid OFF. It's a special OIL tank. Nev