Chainsaw Repair

2 weeks ago I replaced the top on a customers 066, gave him the price for OEM and aftermarket,
he's just a homeowner and uses it for firewood so he went with aftermarket.

I took care of all the servicing it needed and replaced the top end, it's a
standard bore Nikasil plated Forester brand one.

Well it starts, idles, and runs fine but the power is underwhelming at best.
It has a 20" bar running 3/8 chain, and cutting full bar in red oak it's easily out
cut by my Makita 7900.

It has the new style choked off muffler with a 1/4" outlet hole and cage inside. Well I had to mod
the muffler to improve performance, gutted the cage, and took care of the outlet.

I used the thin .5 mm high compression OEM base gasket.

But the performance is still not impressive at all, I've run stock440's and 460's that would eat this saw alive.
Has anyone else run into poor performance with various aftermarket top ends?

Yeah there doesn't seem to be a mechanical reason for the lake of power. No air leak, lean running,
dull chain, clogged air filter, it just seems weak.

I only have a tank of fuel through it, and I'll check the compression tomorrow and see where it's
at.

It just doesn't have that snap to it, when you pull the throttle and under load
it doesn't bog or die under load. But It doesn't cut with authority, and takes forever to get through
a log.

Cale one thing I found when  I was testing alot of after market stuff was they ran alot hotter than the OEM and I tested alot of different models but mostly stuff like 066/660 and 046/460 , I know of all the ones I tested none were as good as OEM , now I have to say the later one sure worked alot better and run alot longer

Thanks for the responses.

If it were my personal saw I'd have it ported, but being
a customer saw I'll just mod the muffler and give it back to the customer.

Now I understand why guys go after the big bore top ends, you need
the extra displacement!

In addition to the size of the ports, I don't know that they get the port timing right on some of them.

Consistancy is also up in the air with some of this stuff. Get a few good ones, and then a bad one.