McCulloch Power Mac 6 Advice needed

[DarkOverCast]

So while stopping in to buy some chainsaw parts for one I was working on for a friend I ended up walking out with two complete power Macs.

They're both later variants with the auto oiler, one has a chain brake. Both have low compression and would randomly lock up. The first one without the chain brake was the cleanest.

I've been in the market for an all metal one hander and judging from what I've read these are supposed to be tough little saws...

I tore this saw down today, the upper piston ring was stuck, it took alot of effort to get it free, this saw has been sitting on a shelf for 10-15+ years.

I figured while I have it torn down this far I mine as well slap a NOS piston and ring set in it right? One question I had was on this chrome lined bore is it unadvisable to hone it? I never get crazy with a hone, just enough to add back crosshatch to set the new rings. Searched everywhere and couldn't find a NOS jug...

Also I figured while it's torn down why not port it too? I've never done this before but get the jist of it, go wider but not taller or shorter or you'll change the timing, and polish it really well. This saw has a bridge right in the middle of the exhaust port that seems rather restrictive.

Also how do I seperate the piston from the rod?? I really can't tell how it comes apart. I'm usually a homelite guy but couldn't pass up on this clean yeller saw and the parts saw to go with it.

My recoil starter drum is also cracking, I read somewhere you can install a speedi sleeve over it to help strengthen it up? That would be cool as the only NOS ones I found were also cracked.

Pics:
Saw all torn down and labeled

Bridge I want to remove when I port the exhaust

Cylinder look okay??

Other parts saw

 

[Nutball]

Perhaps you could thin the divider in the exhaust port and otherwise widen the port slightly. Those can be tricky because if that divider gets too hot, it could expand into the cylinder and cause excessive wear on the piston and ring. It's thickness helps it transfer heat away. But, removing it leaves the port with a very flat top and bottom and sides. It holds the ring in place, and without it, the ring can expand into the port slightly and lock it up unless the port is rounded enough to guide the ring back into the cylinder.

 

[DarkOverCast]

I appreciate your reply. I've been doing lots of research and you are correct, that bridge helps keep the rings in the piston.

Sadly it seems most of the smaller Mac saws lack piston ring pins.

I really just needed a light one hand saw and this fit the bill pretty well. I just kinda felt like doing something more (generally seems to be a problem with me) but today I went back and got some more from the same guy. Two more power Mac 6's with next to no compression, and two Mac 110's, which if I remember correctly are the same cc size, run the same coil/points setup, carb bolt pattern but hair but different carb.

One of these Mac 110's came to life with a little fuel down the throat, but didn't really pass much fuel through the fuel filter and the carb didn't seem to want to pump any fuel.

I tore it all down and cleaned everything because it was very dirty but is probably in 7/10 condition otherwise. Has a short little bar on it, I believe I can use one of my power Mac bars on it with the 1/4" chain.

I think I'm gonna rebuild the carb, and replace a few things on it and run it for now and put the power Mac project on the back burner.

This will also give me a baseline to tell if I make any power increases on it or not...

Plan for the power Mac is to pin the rings with a titanium rod, remove exhaust bridge, narrow the intake, and port time both ports a little. Gonna be considerate since these Macs have goofy transfer ports and don't seem to like alot of timing.

Also going to machine the jug down and try to up the compression just a bit, to let me get more timing out of the exhaust port.

This will probably be an all winter off/on project as I have time/parts.

The two power Macs I got today are the early early style with the banana handle, I really like the ergonomics of it so may just build that one too after I find something that works on the first.

At this point I technically have four jugs to try on and hopefully get one good saw that will be all I need for the smaller stuff that's up high.

I really do appreciate the reply and if I make any progress I'll be sure to post pics here.