Mcculloch pro mac 850

[paul crocker]

Hey guys, could someone please enlighten me on the max rpm for a McCulloch pm850. I am still waiting impatiently for the saw to turn up in the post, but trying to source as much info as I can. Cheers great site too btw

 

[rwoods]

I doubt that info was ever published. I have a just rebuilt 850. If the builder has a tach, I will ask him to measure it after tuning. FWIW these older saws were user tuned by ear, not by using a tach.

Ron

 

[paul crocker]

I doubt that info was ever published. I have a just rebuilt 850. If the builder has a tach, I will ask him to measure it after tuning. FWIW these older saws were user tuned by ear, not by using a tach.

Ron

That would be greatly appreciated thanks Ron, I am certainly looking forward to getting my hands on it and seeing how the old girl cuts? I have to ask what does (FWIW) mean????

 

[bcsman]

For What It's Worth

 

[paul crocker]

For What It's Worth

Yeah sorry my bad, I did figure that out about an hour after I asked the stupid question. Us Aussies must be a bit slow on the draw.

 

[paul crocker]

The good news though, the old girl runs fine. I put my tach on it and its pulling 12000 rpm, seems a tad rich still. But I want to cut a bit then see how it goes. Thanks for your help

 

[bcsman]

For What It's Worth, enjoy your new saw....

 

[rwoods]

Hey guys, could someone please enlighten me on the max rpm for a McCulloch pm850. I am still waiting impatiently for the saw to turn up in the post, but trying to source as much info as I can. Cheers great site too btw

From today's testing, we check the rpm's of each saw after being tuned in the wood. Brian's tach is a photo cell so we measured off the clutch drum. Results were a little surprising to me. Brian's PM 800 - almost 12,900. PM 850 - right at 12,500. My PM 800 - around 11,700 then Brian discovered that the decomp was loose; tighten it up and it jumped to 12,300. DE 80 - consistently 9,900 to 10,000. Brian leaned it some and it hit 11,300 but we put it back to where it was originally tuned.

Ron

 

[paul crocker]

Thanks for the update Ron, I haven't put the tachometer back on it yet. I just did a muffler mod today and seems to be better. I will have to do it again, and use your 12,500 as a bench mark. But my saw seems like a bit of a dog compared to my dads 064. It only has a 16"bar ATM, but going to a 20"soon.I was wondering if I should go to a 8 pin drive sprocket, like on the 064. Which cuts really fast, and plenty of torque. Any thoughts on the drive sprocket? I only cut seasoned hard wood, which has usually been on the ground for years. The other issue I have is, its pumping out a huge amount of oil. But I don't think you can adjust it? Thanks again for your help and advice

 

[paul crocker]

Just in case anyone wants to do a muffler mod on their pm850. What I did was just cut out another plate that fits into the muffler, then just drilled about a 13mm hole right in the centre of the new plate. This eliminates that stupid little flap type plate they have in there, which just seemed to heat up the back of the saw. My hand was getting pretty warm too I might add. But now the exhaust gases just flow straight out the side. I don't know if there is a noticeable improvement in power or not, I haven't cut with it yet.

 

[rwoods]

Paul, I don't know about your Aussie hardwood as I read it is really hard but for what it is worth I run an eight tooth sprocket on my PM 800 and it pulls a 33" bar on our live hardwoods just fine,

The oiler is adjustable. You have to take the front cover off to get to it. You should see a small screw with a lock nut on it. The chainsaw forum has a great thread on Mac oilers by Mark Hemermann.

I don't think a 13 mm hole is large enough. I believe the hole should be as large as the hole in the plate you removed. Search the Mac stickie in the chainsaw forum to find some pictures of a plate I made. I don't think it has enough holes. I just ordered off eBay two different spark arresting screens to try.

Ron