McCulloch Chain Saws

[Jethro 2t sniffer]

Is that the lightweight? Love mine!

It is but wrapped around a 10-10S engine

You're missing a screw there J2t

Yeah it's stripped out. Meaning to re tap for M6 for a good few years now

 

[Little Jerrry]

I only remember using one chip, I believe it was a NOVA II but I cannot confirm that. That was on a 10-10 McCulloch and it certainly would exceed 6,000 RPM...

I swapped chips and it made no difference, so I swapped polarity and bingo, she revs....but it idles way too high (3200rpm ish) with no idle adjuster screw input. With the L jet adjusted to give crisp acceleration the idle sits around 3200rpm, if I richen it up to bring idle down it bogs down. The L jet is out approx 1 turn.

I pressure tested the carb I rebuilt and its fine. I also adjusted the metering lever to be level with the carb body thinking I was getting too much base fuel and it helped a little.

Does anyone have a 7-10 with the Tillotson carb? It seems like the idle screw does next to nothing (hardly makes contact even if screwed right in). I thought maybe the throttle lever could be twisted so its revving higher and also not really being impacted by the idle adjuster screw? It looks fine to me.

Am I wrong in thinking the only other thing to adjust is the metering lever that would have the saw idling so high as its getting lots of fuel? It doesnt surge on anything, runs quite nice but just revs to high.

Funnily enough when i emptied the fuel tank and ran the carb out of fuel, the idling settled down for the last 10 seconds or so?

 

[heimannm]

It could be that your throttle rod is out of shape and not letting the throttle close all the way to the stop. Next time the saw is running try forcing the throttle closed at idle and see if it slows down.

Mark

 

[bob kern]

It could be that your throttle rod is out of shape and not letting the throttle close all the way to the stop. Next time the saw is running try forcing the throttle closed at idle and see if it slows down.

Mark

I agree with Mark. That could be an issue. I have had an obstruction cause that before.

 

[rwoods]

You're missing a screw there J2t

I have heard that said of many MAC enthusiasts.

Ron

 

[docholliday64]

I have a 7-10 with the Tillotson carb - used it last weekend to cut up some firewood - idles fine - my problem is that it runs rich at full throttle (4 strokes). Can this be tuned-out with only one jet to adjust?
At the end of the job, it started misfiring and I realized that the kill switch guts had fallen out, leaving only the top of the switch in place! Looked for the parts, never found them. Fortunately, have some spares at home.

 

[Rallyeguy]

Ive found that on 2 jet carbs on the mccullochs the low jet can have some crossover effect on the high jet. With a fixed high jet, this may also be what you're running into. The saw should four stroke when free revved, but clear up under load in the cut (assuming you're running a sharp chain). If its not clearing up in the cut, you could try to lean out the low a little and then adjust the idle screw accordingly if idle rpm changes. This might get you where you need to be...

 

[docholliday64]

Ive found that on 2 jet carbs on the mccullochs the low jet can have some crossover effect on the high jet. With a fixed high jet, this may also be what you're running into. The saw should four stroke when free revved, but clear up under load in the cut (assuming you're running a sharp chain). If its not clearing up in the cut, you could try to lean out the low a little and then adjust the idle screw accordingly if idle rpm changes. This might get you where you need to be...

Thanks Rallyeguy - I will give that a try once I get the kill switch problem fixed!

 

[Jeffrey F.]

Thanks Rallyeguy - I will give that a try once I get the kill switch problem fixed!

It's kinda like a four barrel primary's first then secondary's but primary's still function.

 

[Rallyeguy]

Just be sure it four strokes when free revved and you wont go too lean. Hate to see a burn down trying to help someone on a forum.... Pistons and cylinders are getting tough to find for the 70 cc McCullochs...

Best of luck...as others said, if you can't find happiness with that carb, you could try to find a two jet version and swap them.

 

[heimannm]

I think the Tillotson they often used on the 70cc saws was a governed carburetor, they always run very rich at high speed as that was the governor does, dumps more fuel as the RPM/vibration increases.

Mark

 

[knightmax]

So I did a thing... Yes it is NOS...

 

[Squareground3691]

So I did a thing... Yes it is NOS...View attachment 1183667View attachment 1183670View attachment 1183673View attachment 1183674View attachment 1183675

Awesome Max,

 

[Jethro 2t sniffer]

Holy crap you must have robbed a cartel for that

 

[heimannm]

Max is the cartel...

 

[knightmax]

Holy crap you must have robbed a cartel for that

I saw it, thought let it go, then I thought when or where will I ever get a chance at a NOS 125c again? So I pulled the trigger. Wife isn't even bothered about it lol. Let a NOS PM 8200 go a couple years back. I regretted it decided not to repeat that mistake. The 125 came with its original box and all paperwork, tooling and a dawg. There was a time in my life I could not even think of spending money on something like this, I am fortunate I have gotten myself to a place where I can. An America Muscle saw made by arguably the most known saw manufacturer in the world, in an era where America was at her height of industrial might in manufacturing. Nostalgic? Yes. Patriotic? Absolutely. Also fortunate, and grateful. This saw is another blessing to me in an already blessed life.

 

[knightmax]

Max is the cartel...

That Mark guy...He funny!

 

[Squareground3691]

I saw it, thought let it go, then I thought when or where will I ever get a chance at a NOS 125c again? So I pulled the trigger. Wife isn't even bothered about it lol. Let a NOS PM 8200 go a couple years back. I regretted it decided not to repeat that mistake. The 125 came with its original box and all paperwork, tooling and a dawg. There was a time in my life I could not even think of spending money on something like this, I am fortunate I have gotten myself to a place where I can. An America Muscle saw made by arguably the most known saw manufacturer in the world, in an era where America was at her height of industrial might in manufacturing. Nostalgic? Yes. Patriotic? Absolutely. Also fortunate, and grateful. This saw is another blessing to me in an already blessed life.

Would of done the same , only go around once in life, go big or go home,

 

[docholliday64]

I think the Tillotson they often used on the 70cc saws was a governed carburetor, they always run very rich at high speed as that was the governor does, dumps more fuel as the RPM/vibration increases.

Mark

That's what I was afraid of - everyone just seems to replace them with SDC's, rather than monkeying with them. I have an SDC 37A that I can slap on (even though my desire was to keep it as original as possible). Did the same thing with a PM 55 that had a single jet Walbro.

 

[Jethro 2t sniffer]

That's what I was afraid of - everyone just seems to replace them with SDC's, rather than monkeying with them. I have an SDC 37A that I can slap on (even though my desire was to keep it as original as possible). Did the same thing with a PM 55 that had a single jet Walbro.

Really like the 37A seems to just have a crispness to it over the other common 65. Not sure why maybe someone does but that's my 2cents. In saying that my 7-10 with the fixed tilly runs real good too. Just tweak the low as lean as it will take n should help a little.