Mcculloch 850 Pro Mac build.

[Sleeper]

Drop starting does not work on a PM850 either... has to have a foot in the loop and a hand on the front handle. 372 (stock XT) is more civilized, I can drop start that no problem with no decomp. Doesn't cut like the 850 though...

 

[Al Smith]

BTW the PM 1000 which of course is a Partner also has a Q but it isn't very large .No decomp valve .

 

[Al Smith]

About all I drop these days are the top handles and the 024 .They all start easy .First start up takes a couple ,after that 95 percent of the time one pull .

 

[FergusonTO35]

Anybody know when McCulloch stopped offering pro saws?

 

[Sleeper]

Anybody know when McCulloch stopped offering pro saws?

I think the last of them were in the very late 80's, maybe very early 90's which is when they started churning out PM 605/610/650 saws for box stores.

 

[Lee H]

So if a super PM850 has the stupid Q port then why is it a super. My 850
has some nut. When I first ran my 800 I was like what is wrong with this
thing. Gutless piece of crap. I can't imagine a logger up grading to a newer
saw from and 850 only to get a new 800. What a disappointment.

 

[Al Smith]

I don't think the Q unless it's high and wide would affect the torque that much at running speeds .It would come under the old thing of port time area open I would think .
When Adam Clark put the soup to that PM 1000 for Wojo I know he dropped the cylinder but I don't know if he carved out the Q .That thing was like roping over a Harley ,my Gawd did it pull hard .

 

[Al Smith]

I don't fully understand exactly how ex port boost ports work .Those I've seen pictures of enter the main port with sideways up angles to about a few degrees ahead of the main opening .They aren't very large .If that was part of that McCulloch idea with the Q or not I have no clue .
I've got some big oak to chunk up this fall when it cools down .If I think about it I'll try to get a comparison between an SP 81 and an early style 850 .

 

[Lee H]

Al, I don't believe the SP81 and the early 850 have the Q port. Although I am far
from and expert in these 10 series saws. I may have a bit of time towards the end
of the month to try my 850 against the 800 against the DE80 against the 81 I have.
The 805 I have is a basket case but I think it had a good cylinder and piston.

 

[Al Smith]

You can use an 850 cylinder but you will need to file off a little bit of the mounting tabs for the coil to get it to align with the flywheel on center .
My 805 also resides in a cardboard box .I have everything but a piston which at the present time is low on priorities of my to do list .It and the canibilized parts from a donor 850 .
I've traveled this road before,it's only a matter of time before, when I least expect it the parts or a donor will show up .

 

[Chainsaw Jim]

Just looks like how one should run to me. He posted another vid today of a ported vs. non-ported PM850. The non-ported wasn't too bad and the ported one just sounded like a way leaned out 850. Definitely ran, but didn't look like a true/fair comparison to me. Would like to see pics of his port work on that saw.

Some say there's nothing to gain by porting an 850. If there is then there is, I'm not the bad guy here. I fixed up a bad cylinder from the factory and gave it a little better port timing...just a little though. If the saws seem close to you then that confirms I did my job following the request of the owner. It wasn't supposed to be a hotrod build, which it is not, but it did turn out better than I expected.
FWIW they both cut on the same log, the same time of day, with the same length bar and chain. Timing the cuts wasn't necessary.
Here's a couple pics of the mess that came from the factory.

 

[heimannm]

Hey Jim - That's ugly and not the way is was supposed to look from the factory. There was supposed to be a kind of lip there around the exhaust port but that one looks like a lot of it has been eaten away. Opening it up and smoothing it out won't hurt, but may not gain a whole lot either.

The PM 850 is strictly a pop up compression release in the top of the head and without the Q port. Actually the DSP (De Stroking Port) is in the cylinder with a passage to the head, there should be an 8-32 SHCS in the side of the cylinder that seal the passageway after it is drilled.

The Q port came on later PM805/800/8200 models. My PM805 is a Q port without the compression release, I have 2 PM 800's, one with the Q without a compression release and one with the Q port and a pop up compression release. The pop up compression release on the PM800/805/8200 models was on the cylinder above the exhaust port, not in the top of the head like the SP and 850 models.

I have a DE80 that came with a replacement 8200 short block that had the pop up compression release bored through to the cylinder, whether that was factor or not I am not sure. The stock DE80 cylinder had the Q port and the pop up compression release above the muffler.

My PM850 Super has the Q port and no pop up compression release.

I did clean up the exhaust port on one PM800 to get rid of some edge similar (but not at bad) as what Jim shows above. Made the saw more challenging to start but did seem to perk it up a bit. I could not duplicate the effort without tearing the saw apart and mapping the port as I have no idea how I really changed the shape.

The stock PM850 is just about a good as any saw ever came from the factory, and without a way to lower the cylinder you can't to a lot of port work to improve it.

Regarding paint, Rustoleum Sunburst Yellow is a very good match for the PM models, the Krylon Safety Yellow is closer to the original shade of the earlier McCulloch saws.

Mark

 

[heimannm]

Just one more thing...don't get in the habit of drop starting your PM850 without the compression release or you will break the flywheel/starter housing.

Mark

 

[Chainsaw Jim]

I've used both of those paints mentioned. One little splash of mix and my hands were yellow from dissolving paint, and that was after a couple weeks of curing time.

 

[Al Smith]

Pictures perhaps .Left is an 850,right is 805 .That 805 BTW had a compression relief valve as well as the Q .

 

[Al Smith]

For posterity sake a pic of the style a Mac 1000 /Partner P100 super

 

[Al Smith]

I might add in this conversation a little tid bit .In my collection of varied and assundry saws I have a 281 Husqvarna which is considered desirable .That saw and any good running 82 cc McCulloch have just about the same amount of cutting power .At the end of a day it would be hard to say which cut more .

 

[Steve]

Pictures perhaps .Left is an 850,right is 805 .That 805 BTW had a compression relief valve as well as the Q .View attachment 86856

Al, you want to sell/trade that 805 cylinder?

 

[Warped5]

I've used both of those paints mentioned. One little splash of mix and my hands were yellow from dissolving paint, and that was after a couple weeks of curing time.

Jim, I've had good success by adding a couple coats of Dupli-Color Clear Engine Enamel on top of my color.

 

[Al Smith]

The 805 cylinder in spite of the saw having the original never sharpened chain had peeled the chrome .Towards the end McCulloch had some quality problems .It would cost more to have it replated than what you find a good one or an 850 cylinder .In addition you'd have to find somebody who would plate a blind end cylinder .
The saw cosmetically looked like a new one because for all intents it was .If I can find a pic I'll post it .