McCulloch Chain Saws

[sawfun9]

I have a few questions for the experts. I have a 797 with thick rings so I assume it's a standard model. The piston is showing the start of aluminum transfer and the top ring is collasped. It looks like this is due to too much oil as there was a ton of hard carbon in and around the exhaust port. I suspect some of it broke off and scored the piston which has some carbon on the top.

Are there new pistons available?
Will a Mac 125 piston work?
If I can find a thin ring piston will this basically make the saw a super?

 

[joeymt33]

Almost done. I have two issues to deal with.

1. Kill switch doesn't work. Not a big deal

2. The manual oiler doesn't work. That sucks!

 

[Wagnerwerks]

I have a few questions for the experts. I have a 797 with thick rings so I assume it's a standard model. The piston is showing the start of aluminum transfer and the top ring is collasped. It looks like this is due to too much oil as there was a ton of hard carbon in and around the exhaust port. I suspect some of it broke off and scored the piston which has some carbon on the top.

Are there new pistons available?
Will a Mac 125 piston work?
If I can find a thin ring piston will this basically make the saw a super?

The Mac guys will surely know this particular issue better than me, but if the piston is nla and is ok from the rings down, you can lightly sand or buff the piston top, clean the ring lands up and then new rings and a cylinder clean up.
Works in a pinch and as long as the cylinder is clean and the saw is tuned properly, it's an ok fix.

 

[rwoods]

Holy moly! It looks like a saw now!

Nice job, Joey. Now put that frame brace in a vice and straighten it; it will be much easier to get your foot in it.

Here's mine. It only has 128psi and the tank has been painted black until where it meets the handle. I assume it was painted to cover up what appears to be a chainsaw cut across the tank that also chewed up part of the gas cap. I would offer it for trade to Mark for a PM800 but he is probably looking for a nicer specimen. Ron

View attachment 260322View attachment 260323View attachment 260324View attachment 260325View attachment 260326

 

[rwoods]

Almost done. I have two issues to deal with.

1. Kill switch doesn't work. Not a big deal

2. The manual oiler doesn't work. That sucks!

Joey, real nice. Manual oiler fix/replacement should be pretty straight forward for you - just a lot of disassembly. BTW if you would be interested in swapping the correct non DSP chain brake for your DSP chain brake, let me know. Ron

 

[joeymt33]

Joey, real nice. Manual oiler fix/replacement should be pretty straight forward for you - just a lot of disassembly. BTW if you would be interested in swapping the correct non DSP chain brake for your DSP chain brake, let me know. Ron

Thanks Ron, that's pretty tempting but the one that's on there is brand new. I think I'll keep the new one. I do think i'll search for a full wrap handle bar though. That half wrap is different and pretty cool to have but I'd like it on another saw that I use a shorter bar on.

BTW, why trade that PM8200? It could be a nice rebuild.

 

[joeymt33]

This was shot while the manual oiler wasn't working and before the kill switch is fixed. I'm finished for the evening. I'll take it back down tomorrow and hopefully get it fixed, tuned, and a video in action.

[video=youtube;vziXVmA-lts]http://www.youtube.com/watch?v=vziXVmA-lts[/video]

 

[rwoods]

Thanks Ron, that's pretty tempting but the one that's on there is brand new. I think I'll keep the new one. I do think i'll search for a full wrap handle bar though. That half wrap is different and pretty cool to have but I'd like it on another saw that I use a shorter bar on.

BTW, why trade that PM8200? It could be a nice rebuild.

Joey, I like to standardize as much as possible. I have enough standard 82cc parts to keep me going for life. I do have an 805 but it is pretty much the same as an 800 (some updated screws, different decal, serial tag and optional frame brace reinforcement). I also have a project DE80 (different tank, intake and carb) but the rest is basically the same and I actually bought it for the standard parts. The 8200's innards are just too different. Besides having all the models appeals to others more than to me so why hang on to something someone else will enjoy more if you can replace it with something that suits you just as well. Ron

 

[joeymt33]

I understand that. I guess one could easily rebuild a PM8200 with the motor from a sp80, sp81, pm850, etc. I don't think anyone could really tell the difference. It would be easier to use the pm800, or 805 now that I think about it.

BTW, did you ever get that SP70 going?

 

[heimannm]

I have a few questions for the experts. I have a 797 with thick rings so I assume it's a standard model. The piston is showing the start of aluminum transfer and the top ring is collasped. It looks like this is due to too much oil as there was a ton of hard carbon in and around the exhaust port. I suspect some of it broke off and scored the piston which has some carbon on the top.

Are there new pistons available?
Will a Mac 125 piston work?
If I can find a thin ring piston will this basically make the saw a super?

I believe that thick rings make a super, seems the thick ones last longer. At least my Super 797 has the thick rings. Try Karts and Parts in Canada, they have a lot of pistons and rings available. Lee may comment as well, he seems to be able to locate parts for the big saws pretty easily.

Mark

 

[sawfun9]

Thanks for the help. I'd asked RandyMac a while ago and he seemed to think the thin rings were the super so maybe there's some confusion. Mine was sold to me as a super but there is no label on the saw. fI also seem to have a non stock flywheel cover as mine is an old cheesegrater type.

 

[leeha]

I have a few questions for the experts. I have a 797 with thick rings so I assume it's a standard model. The piston is showing the start of aluminum transfer and the top ring is collasped. It looks like this is due to too much oil as there was a ton of hard carbon in and around the exhaust port. I suspect some of it broke off and scored the piston which has some carbon on the top.

Are there new pistons available?
Will a Mac 125 piston work?
If I can find a thin ring piston will this basically make the saw a super?

Pistons are getting harder to find. Karts & Parts in Canada,
Terry Ives in Ca. or ebay. A 125 piston will work if you use
the correct rod. I would prefer to stay with a 797 piston.
Super 797's have thick rings. STD 797's have thin rings.
Super 797's also were all yellow and the early ones have
the Tilly HL103 carb. Later Supers have the Walbro SDC carb.
All STD 797's have the flatback carb. And the top of the saw
was all black.


Lee

 

[RandyMac]

I always get things backward.

 

[minosi]

Try Karts and Parts in Canada, they have a lot of pistons and rings available.

Mark

Perry @ Karts and Parts (kartsandparts.ca) 905.934.6299

Good dude, lots of knowledge!

-Andy

 

[watsonr]

Pistons are getting harder to find. Karts & Parts in Canada,
Terry Ives in Ca. or ebay. A 125 piston will work if you use
the correct rod. I would prefer to stay with a 797 piston.
Super 797's have thick rings. STD 797's have thin rings.
Super 797's also were all yellow and the early ones have
the Tilly HL103 carb. Later Supers have the Walbro SDC carb.
All STD 797's have the flatback carb. And the top of the saw
was all black.


Lee

Besides the differences mentioned, any real difference in power... like the ports are different or something like that? And which one do you feel is the better saw? Can a std 797 be made into a super by just changing the rings or piston and rings?

Thanks

 

[cpr]

Standard 797 pistons are identical to the 101s. Check the thick ring piston for a boost port channel (it might be full-circle) and to see if your block has the boost ports. A BP piston will work in a LM S797 (that doesn't have the ports), but a non-BP will not duct mix into the ports, robbing you of some giddyup.

Also, take the time to check the piston clearance. .004 should be about right. Otherwise, look to get the block bored and, since the thin-ring pistons are identical to the 101 pistons, you have lots of choices for over-size ones.

 

[Eccentric]

An easy mistake to make, because...

I always get things backward.

There are 'other' brand saw models that had thick rings in the 'standard' saws and thin rings in the 'Super' versions. They're a different color than the 797's however....

 

[ozflea]

Dont worry too much Randy they will think its old age catching up with you .................................. duh

McBob

 

[rwoods]

I understand that. I guess one could easily rebuild a PM8200 with the motor from a sp80, sp81, pm850, etc. I don't think anyone could really tell the difference. It would be easier to use the pm800, or 805 now that I think about it.

BTW, did you ever get that SP70 going?

It is sitting in a million pieces on the kids' ping pong table. I started to switch to an electronic coil but the mounts are different. So I may just put it back stock. I still don't have the MAC special screw but I'll find someting else to replace it. Have you noticed the prices SP70s have been bringing on eBay? Might make it hard for me to keep it. Ron

 

[sawfun9]

Sorry Randy, and thanks everyone. I'll get a handle on this 797 yet. There's just no a lot of information out there unless you find guys with experience.

Yes, I knew the funny darker yellow, really kind of an orange color saw from Sweden or somewhere, had thin rings on their hot rods.