HELP! Stihl HS80 engine rebuild. NEED HELP (advice)

[WDC1]

Well I have a spare Chinese cylinder kit so I'm going to give it a shot and skim the base. It will be Saturday as I'm waiting for a four jaw chuck to be delivered which will make for a better job.

I'm not certain about the exhaust timing, etc. or what to look for, but the only thing I see on the physical dimensions would be the 2ea. coil mounting bolts which I may need to elongate the holes on the coil using a mill. Straightforward.

The headroom space (in line with the wrist pin, Left – Right) with cly gasket .0754 - .0775 and I need to reduce it to .0300- (120-130 PSI).

I'll keep everyone posted. Any thoughts, please feel free to add your comments.

 

[Mammyrat]

I was just wondering if there are any updates.

 

[Hulpio]

One std procedure is to reduce possible piston ring leak by putting some oil into the cylinder before compression test. Half a teaspoon or something is enough. The rotate engine a couple of rounds without sparkplug so that oil spreads evenly. Now if you test compression again and get remarkably better results the problem is in the piston - piston ring seating area.

 

[WDC1]

Gentlemen, sorry for the delay but this project lives on after a week of vacation and the second week being sick (not of the project).

That said, this is where we stand. As stated for reasons I do not understand the headspace appears to be double what it should have been around thirty thousands. My was "The headroom space (in line with the wrist pin, Left – Right) with cly gasket .0754 - .0775, producing only 65 psi.

I machined off 0.04025, leaving 0.0480 headspace and tested the PSI, which produced 170PSI. A little high but let's see how it goes.

So far, so good, just need to get it together and take it for a test drive. I'm sure something will crop up along the way but I'll keep you posted.

I did find @Wonkydonkeys comments regarding changes in the exhaust timing interesting, but way over my head. But I do appreciate them, it gives me something to worry about at night...lol

Take care. I will keep you posted.
Will