Thanks Otter.

T_F

Test results (a/k/a, a surprise): All three cline regulators showed air bubbles on the laser 120.
All three passed the Tidley underwater pressure test.
All three were tried on a Saito 100. All three showed the same pattern: No problem through about half throttle. Above that air bubbles appeared, and near full throttle it was essentially all air and the Saito stopped.

So I pulled a cline regulator purchased about five years ago, which had run on a Webra 120.

It performed as advertised on the Saito, no air bubbles.

Are we not down to the conclusion that the three current cline regulators won't work on the laser and saito?

I can't quite understand why the air bubbles. That has not been a problem with any of the Cline regulators that I have run.
Maybe the leak is not in the regulator.

Have been running a Cline regulator on a Moki 210 and the engine performs as well most of the time as can be expected of a model engine. It will idle endlessly, runs hard at the top end, yields good tank time, and would be a perfect setup, except for one thing: this side mounted engine will not run when the plane is inverted. It will quit every time. I have checked the inside the tank mechanics-the feed line moves to the top of the tank when the tank is inverted, the clunk moves freely. Any ideas?

If you ran three Clines regulators and they did not work but an old one did, of course it has to be the regulators, and not the fuel system. Sorry to leap to the wrong conclusion above. I have had balky Clines that finally worked after pulling fuel thru them-diconnecting the fuel line from the engine and pulling fuel through them.

Mr. Cline suggested this to me at some point and early in the season it seems to jump start them. Probably clears any goop from them. Anyway in my case, that helped.

Have you had your units apart? If you take them apart, watch that little spring and make sure it doesn't get away.