Thoughts on cheap McCulloch 250?

[Coralillo Lo Pro]

Rebuilt the carb, no luck. Got a working small engine tester, tested at 120 psi, so should start fine with that. Aside from new two stroke gas which it initially worked fine with, not sure what else has changed since I got it and it ran. Still just coughs and sputters but doesn't catch for any longer than that. Sort of left w the choice of bad reed valves or a weak ignition, not sure what else.

 

[heimannm]

If you haven't already, try a fresh spark plug. If it is still an ignition issue, pop the flywheel off and clean and gap the points, 0.018-0.020".

Mark

 

[Coralillo Lo Pro]

If you haven't already, try a fresh spark plug. If it is still an ignition issue, pop the flywheel off and clean and gap the points, 0.018-0.020".

Mark

cleaned the plug well, but haven't tried a new one yet. Just cleaned and gapped the points - that was a trip down memory lane, hadn't cleaned points in at least 20 years. My finicky Pinto ignition in high school always had dirty points, reminds me a bit of this sputtering not starting behavior. But will get new plug too, I need to get new plugs for my Stihls as well.

 

[Okie]

Just a hint on them type Mac's: (from experience)

The majority of them that I have seen and that I have want to start with a full throttle opening, hot or cold.
(and I hold the throttle wide open with the toe of my shoe to start them. (with the saw on the ground)
I also have a number 10 solid copper wire loop that I can slide up over the throttle to hold the throttle open and then when it fires for a run just slide the wire down off the throttle.
Lots of time to slide the wire down or remove the shoe toe because them engines do not rev up fast and scream like the Stihls and others. They just sputter to life and are a low rpm, high torque engine.
Also when cold just prime them through the muffler. After priming hold the throttle wide open when starting.
What model/type is your carb??

 

[rogue60]

I had a nice example of one done a few cuts and quickly gave it away to a mate.. Hands down one of the slowest cutting saws I've ever pulled the trigger on

 

[Coralillo Lo Pro]

Just a hint on them type Mac's: (from experience)

The majority of them that I have seen and that I have want to start with a full throttle opening, hot or cold.
(and I hold the throttle wide open with the toe of my shoe to start them. (with the saw on the ground)
I also have a number 10 solid copper wire loop that I can slide up over the throttle to hold the throttle open and then when it fires for a run just slide the wire down off the throttle.
Lots of time to slide the wire down or remove the shoe toe because them engines do not rev up fast and scream like the Stihls and others. They just sputter to life and are a low rpm, high torque engine.
Also when cold just prime them through the muffler. After priming hold the throttle wide open when starting.
What model/type is your carb??

Tillotson HL63
Yeah, from when it was running and everything I've learned about them I gather they're very slow rpm saws. I tried putting a clamp on the throttle before and didn't help. But I've done a bunch to it since then. Will get around to it trying to start it again at some point, have a million other things to do than work on a saw I'm not likely to use. The manual oiler, and the fact it doesn't work, is the main deal breaker, I'd have some fun cutting with it otherwise but can hardly be bothered to repair the oiler just so I can't frantically push it nonstop lol. A pair of working 87cc Stihls render it kinda useless. Will probably flip it to a collector once I have it working okay. Don't have more than $100 invested in it yet.

 

[Coralillo Lo Pro]

I had a nice example of one done a few cuts and quickly gave it away to a mate.. Hands down one of the slowest cutting saws I've ever pulled the trigger on

yeah, that's a beauty but like you say, saws have come a long way since then and just about anything in the 80-90cc class is gonna run circles around it for speed. Now my old 87cc Stihl rebuilds seem good finally, they're an infinitely better working saw.

 

[Okie]

I really like to use my old big heavy Mac's after I get a log down. I use lighter weight saws for felling and trimming.
They really have a nice sound and have a way of getting into your blood.
The 404 chains are easy to sharpen and do not need to turn fast to throw lots of big chips.
What I think does most of them in is not exercising them often enough

Your Tillotson HL63 is easy to work on.
Lots of service info for it at the Tillotson site.
Be sure and clean the sintered iron input filter good.

Here is a link to download/save and view the HL series of tillotsons

https://tillotson.ie/wp-content/uploads/2015/07/techinfo_hl_eur.pdf

 

[Coralillo Lo Pro]

I really like to use my old big heavy Mac's after I get a log down. I use lighter weight saws for felling and trimming.
They really have a nice sound and have a way of getting into your blood.
The 404 chains are easy to sharpen and do not need to turn fast to throw lots of big chips.
What I think does most of them in is not exercising them often enough

I thought it cut okay when I had it running for a bit the first time I put the new gas in. The .404 chain was in hideous shape, teeth on one side filed more than 1/8" back than on the other side, I tried evening it up some, but my cheap grinder is too weak for major chain grinding, but got both sides sharp at least and a little more even. Seems like it would cut respectably w new .404 chain. I like the idea of burying it in 24" logs and using its weight to do the work, I can see it would be a nice saw for that. I don't do any felling and sectioning, though, just milling and occasional big big rounds, and I have an MS880 for the big work. I love the sound of it, though. Committed to restoring it to decent working order whether I need it or not, it's a nice piece of machinery. Cleaned out the whole oil tank this evening, may be why oiler wasn't working, lot of glop in there. and rinsed it out w gasoline. Have to double check I didn't do something dumb like reverse the gasket/diaphragm order on the carb. Checked spark again, looks good. Tried priming through muffler with no luck. Little baffled why I'm not even getting a cough at the moment. The more I work on it the worse it gets lol.

 

[rogue60]

yeah, that's a beauty but like you say, saws have come a long way since then and just about anything in the 80-90cc class is gonna run circles around it for speed. Now my old 87cc Stihl rebuilds seem good finally, they're an infinitely better working saw.

I think the Super is the more desirable better running one to own from what I've read.

 

[Okie]

See if the spark plug is wet.

If spark plug is wet install a new correct type plug gapped correctly.
If it has spark and does not start after the new plug let it set/rest for 24 hours and without lots of choking and the throttle wide open.

Sometimes the crankcase will flood and letting them set for several hours will get a run.

If it won't start after setting for several hours and the spark plug is not getting wet from using ONLY the choke on the saw (no prime) You need to check if the fuel pump in the carb is working.
You do this by removing the STUD BOLT that holds the air breather on. When removed it has a passage in the threaded hole into the top of the carb to use a low pressure fuel pump gauge that will detect 1 psi or so. Several pulls on the rope should produce some pressure. I do not remember the exact pressure but several pulls on the rope should produce around .3-.5 pressure and this indicates that the CARB fuel pump is pumping gas to the carb for a start/run. Mac had a adapter that allowed connecting a gauge and hose for testing that the fuel pump would work.
I made a adapter for such.
Do not lose the little copper seal washer if you remove the stud bolt for testing.
If you do not see any pressure you then pressure test the carb for air leaks and the fuel line from the tank to the carb. If you see any fuel at all in the air box is not a good thing, indicates that the carb may not pump enough gas AND that OEM Mac fuel line clamp on the bottom of the carb barb is a source of fuel suction trouble also. (carb pump will suck air due to the clamp not sealing the fuel line good)

 

[Coralillo Lo Pro]

See if the spark plug is wet.

Okay, after reassembly, with throttle clamped down it roared up to speed briefly and then died a few times. Next problem is starter is binding up so having trouble consistently pulling cord. There's an enormous amount of play in one of the pawl dogs so it swings up and binds up on the fanwheel. Tried just putting an e-clip on to take the play out, but the rivet post holding the pawl dog down just pulls out farther when I do. Guess I need a new rivet pawl post - found some on Ebay but for the 10 saws haven't matched anything for sure to a 250. Or just another flywheel with good dogs, there's one for $32 or so on Ebay. Pulled the rivet post out and the raised area on the flywheel with the hole for the rivet post has a piece cracked off around where the post goes into it so it's missing 1/3 of the holding power on the post. I tried brazing it with some expensive filler paste I have but that wouldn't stick at all - so filled it with JB Weld. The rivet post just needed a little more bond to keep it from riding up like it was doing, so hopefully this does the trick.
Btw, I put a hose clamp on the carb barb right after I got it because it was leaking a lot of fuel there - the OEM spring clamp is good for nothing at this point.
Will have to tune it when I have it running, but do you know what the standard jet settings are for the Tillotson HL carb? I have both the high and low set at one turn out at the moment.

 

[mudrat2]

I have an old 250 around here that was given to me in the late '80s. Bugger to start, leaked gas, and heavy.... Figured that is why it was given to me.

Gas leak was due to small bubble in the casting on the bottom. Fixed with a dab of epoxy. Hard start was helped by adding a short piece of coat hanger wire to the choke setup so it would hold the throttle open a crack, gives it a fast idle setting. Never did figure out a way to reduce the weight. ;-)

Still has the original bar with the grooved pully on the nose.

 

[Coralillo Lo Pro]

I have an old 250 around here that was given to me in the late '80s. Bugger to start, leaked gas, and heavy.... Figured that is why it was given to me.

Gas leak was due to small bubble in the casting on the bottom. Fixed with a dab of epoxy. Hard start was helped by adding a short piece of coat hanger wire to the choke setup so it would hold the throttle open a crack, gives it a fast idle setting. Never did figure out a way to reduce the weight. ;-)

Still has the original bar with the grooved pully on the nose.

By the early 80's it was a pretty archaic saw compared to what Stihl was coming out with in the 045/056 Super/Magnum line. Kinda like Packard's heavy Straight 8 becoming obsolete with Ford and GM adopting the V-8 in the early 1950's. Bars were nice, I like the old roller/pulley noses. Those noses have become valuable among hot/fast saw enthusiasts. Hoping mine becomes a good runner with new rings - does want to run and did when I bought it with the heavy 16:1 40 weight oil mix, just compression a shade too low with two cycle gas. Pulls as easy as a 50cc saw at the moment, and my understanding is it should hurt your shoulder with proper compression. Will just go to a collector though once I get it going again. The weight is just impossible for doing anything practical with it but putting it on a go kart.

 

[Okie]

I have an old 250 around here that was given to me in the late '80s. Bugger to start, leaked gas, and heavy.... Figured that is why it was given to me.

Gas leak was due to small bubble in the casting on the bottom. Fixed with a dab of epoxy. Hard start was helped by adding a short piece of coat hanger wire to the choke setup so it would hold the throttle open a crack, gives it a fast idle setting. Never did figure out a way to reduce the weight. ;-)

Still has the original bar with the grooved pully on the nose.

You say:
Hard start was helped by adding a short piece of coat hanger wire to the choke setup so it would hold the throttle open a crack, gives it a fast idle setting.

I do this fast idle setting also to get a more user friendly start on the 1-43's thru the 250's by using a #10 solid copper electrical wire wrapped around the throttle trigger to give her some throttle when starting and when it starts just push the copper wire down off the trigger and leave it on the handle for next time. These saws do not rev up fast so lots of time to reduce the throttle rpms when they first start even at full throttle.
When coming out of storage I can sometimes just prime the saw through the muffler with 50:1 especially if it has the cast type muffler which is a direct shot to the piston and not have to remove the air filter cover plate.

 

[mudrat2]

I would have to pull it apart and take a look to be sure, but as I recall it, pull the throttle, pull the choke, release the throttle and a bend in the hanger wire drops down and keeps the throttle partly open. When it starts and you push in the choke, the wire keeps the throttle cracked open until you open the throttle and then the wire moves out of the way and everything operates like normal.

Made it a lot easier to start.

If anyone is interested I can open it up and take a photo or two.

 

[heimannm]

It would be interesting to see, and the same solution would apply to a number of other front tank models.

Mark

 

[Coralillo Lo Pro]

After first catch on choke, and getting it to keep running briefly when I released the choke, I then held the throttle down to restart it and it actually caught and ran awhile today and revved kind of decently before eventually losing power and dying. Compression is low but seems enough to run so may yet just be a matter of tuning it. I cleaned the points initially, but need to pull the flywheel and check the gap on them. I misplaced my feeler gauges for awhile. It's just sort of a background project I tinker with when I have time.

 

[Coralillo Lo Pro]

Ran it about three minutes today and briefly got it past choppy sounding to full revs at one point though mostly reverted to half power. After that I could only get it going briefly while trying a lot of jet adjustments and finally flooded it too bad to do anything more til it dries out. Given my experience with my 045 and 056 Supers where I chased flooding forever tinkering w fuel things until I figured out it was the ignitions almost all along, I suspect I'm chasing my tail til I make sure the points are gapped right. But encouraged how strong it sounded (even with fairly low compression) the brief times it revved full, so feel like I'm on the right track. Gapped the points, cleaned them, put it back together and no spark. Took it apart again found I'd gapped the points a bit wide, re-gapped, cleaned everything again, put it back together, had spark. Sputtered first time on choke, sputtered with choke off, then back to no life again.
Suppose I could buy a new condenser first, or I could just get a chip - they're cheap enough - and skip dealing w the points and condenser anymore, and then get a coil if that doesn't do it. Not a hundred percent certain, but think the whole problem is erratic spark. It has spark on my tester when it's working at all and no spark when it's not, so pretty clearly an ignition issue. Ordered the chip so I don't have to bother pulling flywheels again. Tired of it enough on my 045/056 Supers every time I was chasing ignition problems.

 

[mudrat2]

Finally remembered to take some photos.

When you pull the throttle then engage the choke, a bend in the wire added to the throttle catches against the choke linkage and holds the throttle open just a crack.

Saw has the original bar on it.