MCCULLOCH McCulloch 797 help

[Scott Kelsey]

I have been reading around but would like peoples opinions from here. What was the recommended bar length from McCulloch that a 797 could run? What have you personally witnessed or ran as far as bar length?

 

[sawfun]

A standard 797 can run more bar than a super 797. Chain and wood type will also deturmine max bar length. I have an PNW loggers saw that has a 36" bar but with 1/2" full chisel. That is probably max bar length for that chain in our type of wood (big Doug Fir). With .404 chisel, 60" is no problem, and some old timers say 72" is max, which is about a foot more than the super or a 125 will do. This is probably due to the higher torque the 797 has over the other two mentioned saws. Old timers used raker height, with regarding type of wood to be cut, which is crucial in regards to efficient large wood/ long bar cutting. I've run 36" .404 and mine cuts like a gear drive with that setup. I've run 50" and it isn't working the saw much at that length buried in large for.

 

[Scott Kelsey]

Sawfun, thanks for the reply. I was reading Mike's Acres and read that the 797s general construction is of magnesium. Would that include parts such as these? The oil and fuel tanks as well? When I picked these parts up they are extremely light.

 

[Lee H]

The only parts that are aluminum are the cylinder block, cylinder cover and flywheel.

 

[Scott Kelsey]

I need a decompression valve for another 797 I picked up. Would anyone be able to tell me if one from another saw would cross? I can't seem to find a specific valve for a 797.

 

[heimannm]

PN 63615 used on the 795, 895, 797, 797 Super.

Mark

 

[Scott Kelsey]

Picked up another 797 out of Pennsylvania. I don't believe it is in to bad of shape. Has the original style muffler than needs a small amount of welding which I will be able to take care of. It needs a decompression valve, hence the reason I asked in this post above. It will also need some work done to the exhaust mounting holes as I believe someone stripped them out and repair them with some form of insert. Sure has a good 30 year old smell of gasoline to it. Has the original carburetor as well. Out of all the hobbies I have had I believe chainsaws are the most fun and peaceful to work on for me.

 

[Scott Kelsey]

Pictures

 

[hseII]

Picked up another 797 out of Pennsylvania. I don't believe it is in to bad of shape. Has the original style muffler than needs a small amount of welding which I will be able to take care of. It needs a decompression valve, hence the reason I asked in this post above. It will also need some work done to the exhaust mounting holes as I believe someone stripped them out and repair them with some form of insert. Sure has a good 30 year old smell of gasoline to it. Has the original carburetor as well. Out of all the hobbies I have had I believe chainsaws are the most fun and peaceful to work on for me.

WOW!


Sent from my iPhone using Jon1212 Pro

 

[heimannm]

I think most of the large frame saws had threaded inserts for the exhaust that were part of the block so they were not called out in any IPL's.

Mark

 

[Lee H]

I think most of the large frame saws had threaded inserts for the exhaust that were part of the block so they were not called out in any IPL's.

Mark

Yes they did, They were actually molded into the block. Screw size was 10-24. When the
105's and 125's came out they went to a 5/16 thread without the inserts.

 

[Scott Kelsey]

This is very interesting information Heimannm & Lee H. I imagine inserts of some sort can be had from some supply company.

 

[Al Smith]

They had some weird thread sizes .I've said before about the flywheel of a 125 that had 12-24 threads in the holes you mount the bar puller .It took me forever to find any long enough and they didn't hold .Hardest pulling flywheel of any I had ever worked on .I either punch them out to 1/4" or 5/16" .That fact there might have been why somebody had bypassed the points and used an Atom Arc trigger .They couldn't find the damned bolts . At any rate the points were still there ,I hooked them back up and every thing was okey dokey .The holes might have been a factory screw up ?

 

[Lee H]

Al, Every one of the large frame Mac's weather it be a 797, 795, 125, 250, 143, and so on all have had
1/4-20 threaded holes in the flywheel. Never seen one with 12-24 threads and never had a problem
removing one either.

 

[Al Smith]

All I could figure out was possibly they had heat shrunk it or something .Evidently it had been off at one time because it had I think a 2.5 degree offset key .Which with the Atom Arc would have advanced it .That thing would not have done anything with the points unless they were set wide .I set them a tad over and might have gotten couple more but not enough to jerk your arm off . 123 cc could hurt you .

 

[Scott Kelsey]

Did some exploratory work on the new 797 I purchased. Was eye opening after I opened up the stuffer. Was full of what you see in the picture. I have never seen anything like it. I had plans to completely tear apart the saw anyway so this gives me more reasons to. I did a lot of soaking, gently cleaned with tools, and blowing out with an air nozzle. The crank bearings, crank, rod, and needle bearings have no rust or pitting, and the crank is rolling over smoothly. The piston looks good and the bore is in decent shape from what I can see, but time will tell once I get everything apart.

I have been curious does anyone know what saws such as the 797, Super 797, CP125, and SP125 cost new?

 

[Lee H]

That corrosion is caused by moisture combined with the magnesium parts
which are the stuffer and the left side case. You need to make sure all of that
crap is cleaned out as the reaction can keep going.

 

[Scott Kelsey]

Thank you Lee. I will make sure I stop it.