Stihl 026 bogging down - not sure where to proceed

[302w]

I have a Stihl 026 that I recently rebuilt. It is an unloved saw I sort of inherited.

New AM P/C
New AM carb
New fuel lines and filter (using generic fuel line)
New 18" rollomatic bar
New 18" 3/8 full chisel (yellow) chain
New OE air filter

Saw starts, idles, and revs nicely. Oils well. Cuts very nicely, but starts to bog down quickly when it meets resistance. I was cutting a 12" ash log and would effortlessly cut through 4" of the log, and the chain struggled/stopped by the midpoint.

I had the carb set to one full turn out on the H screw and L screw. Turning the H screw out in quarter turn increments didn't help much.

This saw has been used quite a bit by the previous owner. I'm thinking it is either:

Clutch (can I swap with an 039 to test?)
Crank case gasket leak (did not split case)
Fuel line (not sure if a pre-molded line is correct)

What are your thoughts?

 

[Wonkydonkey]

I would guess it’s the am p&c. Because of poor timings and/or the size of ports…I'm guessing it’s tuned correctly ie 4stroking around 13.5k and cleans up in the cut and then boggs

but I'd like to see others thoughts..

 

[Automender]

I found that aftermarket PCs are not made to the same specs as OEM. I recently rebuilt a TS420 concrete saw and used a AM PC. I measured the squish which is the distance of the piston to the upper limit of travel. This measurement when compared to the OEM measurement will give a heads up on the final compression. The difference was significant plus if I used the aftermarket jug gasket it would have been even worst. I was able to eliminate the gasket which helped to raise the final compression to close to OEM specs.

 

[blacksmith]

I know that I have a 200t that needed a carb. I cheaped out and got an AM carb. It was ok for a little while. Then the same thing started happening to my saw as what's happening to yours.
I bought an OEM carb and the issue went away.

That would be the easiest thing to change out first.
It could also be the P/C as someone else said or a combination of both.