PP455 / P45 compression concerns

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CamMann

ArboristSite Operative
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Sep 1, 2018
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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!
 
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