PP455 / P45 low compression concerns

[CamMann]

I recently bought two saws with the same powerhead, one is a Poulan Pro 455 chainsaw and the other is a Target concrete saw, both essentially Pioneer P45 powerheads. They both have a feeling of low compression when pulled over without using the decompression valves. Now, they’re 72cc, and I have 42cc saws that give as much resistance when pulled over!

Both P&C sets looked excellent through the exhaust ports, figured I’d try my luck with new rings & fresh crosshatching. So, I pulled off the cylinders to investigate & see what style of rings they have, and the rings look quite clean w/ plenty of spring left! I’m a bit confused. Gaskets looked good. Decompression valves seem to seat well. Everything looks fine!

Is there something about this model that just gives it that comparatively low-comp feeling when pulling over? I guess I should have just ran them and seen how they performed, but they just didn’t feel right to me. I see the cylinders & crankcases have booster ports as opposed to just two transfers like every other saw I’ve pulled apart. That wouldn’t affect the feel, would it?

Any feedback would be appreciated. Thanks & all the best!

 

[pioneerguy600]

Really need a comp tester to know for certain, some say try holding the saw up in the air holding the recoil handle, see how quickly the powerhead drops. If rapidly then compression is likely low. A saw with a large diameter recoil spool feels much easier to pull over than a saw with a small dia one. What feels easy to one person may feel much different to another.