Stihl 026 idle changes when on its side.

[777funk]

I've long read this is seals and always assumed the saw has bad seals. Today after 10 years of it running like this, I decided to tear it down and pressure/vacuum test.

I sealed the exhaust port with an innertube patch, dropped the whole saw in a bucket of water full to the intake with my thumb over the intake manifold where the carb meets it and put 10 psi into the impulse line. I expected instant bubbles on the clutch side and...

NOTHING.

So I spun the engine over a few times slowly and put pressure on the PTO shaft as well as flywheel to simulate torque. Still nothing.

Now 7in HG on the MightyVac pump tester (out of the water of course) and it holds for as long as I had patience to watch it without the needle budging.

So from what I can see, the saw is good and tight. I'm not sure what to think. Anywhere else I can look?

 

[Woodslasher]

Sounds like a relatively common issue where fuel will puddle in the bottom of the intake boot, so when you tip it on its side it gets a surge of fuel followed by a consistently larger amount of fuel. I wouldn't worry about it.