McCulloch Chain Saws

[heimannm]

Lots of complete old tractors...

Mark

 

[Steve NW WI]

Lots of complete old tractors...

Mark

As Tim the Tool Man would say:

[video]http://www.youtube.com/embed/LehNm4VVqJI[/video]

 

[cpr]

Tried adjusting the throttle stop, and it did improve a little bit. However, it still is slower than it should be.

If it wasn't getting enough fuel it would, it'd be screaming, right? It doesn't scream at all, in the cut or out of the cut. It clears up from the out of cut burble when the bar is buried.

Anyone else think that since a 36" (according to a few folks here) is the max recommended bar length, then 24" with an 8 pin may be slowing it down so much that it's not in the good power band? The ports are a little different (and higher due to the teardrop) than stock... maybe less low end torque and more upper end power resulted?


So, what I am going to do is swap a 7 pin clutch drum on, and also check the points again to make sure that hasn't changed. It is snatching the recoil handle a little more now than before, so there may be a timing issue there.


Going to have to fix the clutch cover/recoil assembly, again. It is getting beat to hell on this thing and has developed not one, but two cracks. Thankfully not in the repair area I stop drilled. The one without the hole stop drilled at the end, however...

Yes, I do pull the recoil cord out before shutting it down... it's a must with these big Macs. Still, those recoil snatch backs on attempt to get it started are hard on the recoil assembly.


It also needed to be retuned for it to idle and run. (it has gotten a lot cooler out since the last time I ran it)


But then again regarding bar lengths... IIRC, RandyMac claims to have run a 36" bar with an 8 pin on a PM850 in soft wood. So should the 790 be able to pull a 24" with an 8 pin? Or is the difference between 3/8" (.375") and .404" really enough to require a lot more torque and power to run the latter, thus require a 7 pin?

I don't remember you raising the exhaust at all, just transfers and what you did was mild. That's not it. There's something in the tune and/or the chain. Does your flattie have the check ball? Could be sticking down and or dirty in there and not giving you all of the fuel no matter where you have the needles adjusted to.

 

[badhabit]

Wondering if you guys might be able to throw some direction my way.

I have a McCulloch 7-10 I just picked up. Didn't want to start after bringing it home so I put new fuel in it, and I took apart the carb to check the condition of the carb and diaphrams. Looked like there was some dried up fuel in there.

Cleaned everything out and put in a newer (but old) diaphram I had laying around (the round one) and reassembled it.

I can get the saw to start now but that's usually after a lot (at least 30 or so) of pulls on it. After the saw is started up and ran it will restart no problem. Once it gets cold it just does not want to start. Any suggestions on what I should try next? I am thinking I should just put in a new carb kit. I can't remember if I put a new spark plug in it so I will do that for sure.

Love the saw, have already cut up a cord of wood or so with it, great saw with good power at around 70cc's.

Thanks,

Jake

 

[promac850]

I don't remember you raising the exhaust at all, just transfers and what you did was mild. That's not it. There's something in the tune and/or the chain. Does your flattie have the check ball? Could be sticking down and or dirty in there and not giving you all of the fuel no matter where you have the needles adjusted to.

Not the exhaust... the transfers. The exhaust simply had its ports smoothed out to get rid of the carbon trapping square to round transition.

As for the carb, I'm thinking the check ball or sintered element is a possible cause like you mention.

Still trying to figure out if that would be one of the many justifications for buying an ultrasonic cleaner... though in all honesty, I have no idea where the hell I'd put the US cleaner. Guess I'd have to clean up the shop a bit and make a spot for it.

Well, I gotta go fix up my "junk" storage shed... it's leaning a bit at the top over the entryway. Not good.

 

[Warped5]

Not the exhaust... the transfers. The exhaust simply had its ports smoothed out to get rid of the carbon trapping square to round transition.

As for the carb, I'm thinking the check ball or sintered element is a possible cause like you mention.

Still trying to figure out if that would be one of the many justifications for buying an ultrasonic cleaner... though in all honesty, I have no idea where the hell I'd put the US cleaner. Guess I'd have to clean up the shop a bit and make a spot for it.

Well, I gotta go fix up my "junk" storage shed... it's leaning a bit at the top over the entryway. Not good.

Got mine at HFT for like $29, the small one. Handles a carb just fine, since that's pretty much all that ever goes in there.

Snag a 20% off coupon from one of those free car/truck/RV/cycle magazines at the store, or grab one from AARP magazine.

Good luck!

P.S. Shop Weasel, answer your PMs please ... :msp_angry:

 

[badhabit]

Going to go pick up a Pro Mac 10-10A for like $40 off a guy on Craigslist here in about an hour .

What worries me is he said he put straight gas in it to see if he could get it to fire up as he found it in one of his properties garage's

 

[Warped5]

Going to go pick up a Pro Mac 10-10A for like $40 off a guy on Craigslist here in about an hour .

What worries me is he said he put straight gas in it to see if he could get it to fire up as he found it in one of his properties garage's

Test the compression and if it's less than acceptable, give him $5 before you whack him with it.

Poor guy has to get some common sense somehow. :msp_unsure:

 

[mad murdock]

Wondering if you guys might be able to throw some direction my way.

I have a McCulloch 7-10 I just picked up. Didn't want to start after bringing it home so I put new fuel in it, and I took apart the carb to check the condition of the carb and diaphrams. Looked like there was some dried up fuel in there.

Cleaned everything out and put in a newer (but old) diaphram I had laying around (the round one) and reassembled it.

I can get the saw to start now but that's usually after a lot (at least 30 or so) of pulls on it. After the saw is started up and ran it will restart no problem. Once it gets cold it just does not want to start. Any suggestions on what I should try next? I am thinking I should just put in a new carb kit. I can't remember if I put a new spark plug in it so I will do that for sure.

Love the saw, have already cut up a cord of wood or so with it, great saw with good power at around 70cc's.

Thanks,

Jake

I would put a kit in the carb, they are only about 12 bucks. Well worth it, after you kit it, and retune, the thing should start in 2-4 pulls cold, even after sitting around not used for a few weeks. I did that to my PM700 and it starts like that all the time, When warm usually first pull sometimes 2.
Great saw!

 

[Duke Thieroff]

Not the exhaust... the transfers. The exhaust simply had its ports smoothed out to get rid of the carbon trapping square to round transition.

As for the carb, I'm thinking the check ball or sintered element is a possible cause like you mention.

Still trying to figure out if that would be one of the many justifications for buying an ultrasonic cleaner... though in all honesty, I have no idea where the hell I'd put the US cleaner. Guess I'd have to clean up the shop a bit and make a spot for it.

Well, I gotta go fix up my "junk" storage shed... it's leaning a bit at the top over the entryway. Not good.

Kyle,

Put a known working danged HL on it to see if the saw runs correctly. After you determine the result of that conquest, you can either relate the issues to your carb, or to some other system on the saw.

My 1-76 has a Mac carb on it, and I had it running fine, but it was awful finnicky. I put it up in dry storage for a few months, one day I got the bug to hear it run. No dice man, couldn't get that thing to run worth a crap. It would pop on prime, and just start to draw fuel, then nothing.

I've been in a lot of old barns full of Macs....9 outta 10 have the flatties on em ripped halfway off....that oughta tell you something. If you put a known good HL on it and you are still experiencing the same issues that would either indicate an air leak somewhere or an ignition issue.


Chris

 

[promac850]

Got mine at HFT for like $29, the small one. Handles a carb just fine, since that's pretty much all that ever goes in there.

Snag a 20% off coupon from one of those free car/truck/RV/cycle magazines at the store, or grab one from AARP magazine.

Good luck!

P.S. Shop Weasel, answer your PMs please ... :msp_angry:

I was thinking the big one might work for cylinders and other engine parts though... I only want to spend money on one, not talk myself into a bigger one after already having the small one... really don't need two of them laying around.

I'll get one tomorrow and yeah, 20% coupon will be used for sure. Might get a couple other things there as well since it's all the way across town.

P.S.

Shop Weasel? Who's that?

 

[8433jeff]

The two US cleaner is the plan, too hard to keep the big one clean for carbs.

 

[heimannm]

On the drive today I stopped in an old, familiar shop in Amish country.

I now have another 10-10S and another PM800 for trading stock, as well as a complete 610 and 300 (the old one) that had to be included to make the deal.

I'll try to get a photo of the back of the truck tonight...

Mark

 

[heimannm]

Here they are. The 10-10S and the PM800 both run, two pulls for the 800 and 4 for the 10-10S...

I didn't try the 610 or the 300 but the 300 is equipped with the Tillotson HL63.

Lots of misc gaskets on the pieces of plywood. That brown looking thing in front of the PM6 box is one of those "Keep Indiana Green with McCulloch Chain Saws". I am not sure yet what I will do with the parts rack but I expect I will find something. I started out this week looking for a couple of the "full wrap" style handles for the Super 33's in the attic but only found a couple of the standard ones, plus a few more handles.

Lots more goodies in the boxes including a NOS cylinder for the SP81 and a +0.020" 795 cylinder and a couple of the DSP valves for the 795 block.

Mark

 

[heimannm]

This genuine McCulloch breaker spinner was a nice addition as well.

I think my truck is getting full.

Mark

 

[watsonr]

Looks like yesterday was a MAC day! :msp_w00t:

My measly haul

 

[boda65]

A picture of a nice load of hickory I got yesterday. Cut about 95% of it with my 10-10s and 5% with my Power Mac 6. Call me weird, but I love that little saw, I don't for the life of me know why they came out with those satanic Mini Macs when they had such a fine small saw.

 

[heimannm]

Looks like some big old brutes there Randy!

Jim, why not the PM800?

Mark

 

[Chris Crouse]

DSP Valve Problems?

I have a Pro Mac 850 with a beat up push pull DSP valve I think is giving me problems. The spring clips that are supposed to hold the valve open or closed have been bent up to where they don't do the job anymore. The valve opens and closes very easily as a result. Are these fine thread DSP valves notorious problem spots? Is there a good way to eliminate the DSP either via it's port or the "clean-out"? It seems like I would have to bottom out a long bolt in the DSP hole to remove it properly.

Thanks, Chris

 

[Eccentric]

I have a Pro Mac 850 with a beat up push pull DSP valve I think is giving me problems. The spring clips that are supposed to hold the valve open or closed have been bent up to where they don't do the job anymore. The valve opens and closes very easily as a result. Are these fine thread DSP valves notorious problem spots? Is there a good way to eliminate the DSP either via it's port or the "clean-out"? It seems like I would have to bottom out a long bolt in the DSP hole to remove it properly.

Thanks, Chris

The fine thread DSP valve is easy and cheap to replace. When they won't stay open while cranking, it's time to replace them. I wouldn't eliminate the DSP valve with a bolt, as the starter parts on these saws are somewhat marginal for a high compression 82cc saw. The DSP valve takes a lot of the strain off of them. Remember that they're the same parts that were designed for the 54cc saws. The later saws without a DSP valve (PM800) have the 'Q port' exhaust port to lessen the strain on the starter parts (although the DSP valve is more effective at doing this job).....