McCulloch Chain Saws

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Back on track. :rock: Ron
 
Hey ShopMonkey!

I have apparently been anointed the title of 'WingNut' by Pope RandyMac ....

Just want to let you know you aren't alone! :ices_rofl:

P.S. I just think he's still stingin' a bit over the 'Red Hat Incident'

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Hey, when the PM700 starts getting low on fuel, she starts revving out of control!

Never seen one act like that before. They usually lean out a little then sputter and quit.
 
Hey, when the PM700 starts getting low on fuel, she starts revving out of control!

Never seen one act like that before. They usually lean out a little then sputter and quit.

A lot of two strokes do that. Even my lawn boy revs up right before it runs out and it also has a terrible spark knock sound when it leans out. I try to not run it completely out of fuel. You can always pull the choke out if you don't want it to rev so high.
 
Yeah, I know 2-strokes lean out when they start running out of fuel...

but this one just runs AWAY. It'll rev up to screaming even if I let go of the throttle. I have to hit the kill switch.
 
Yeah, I know 2-strokes lean out when they start running out of fuel...

but this one just runs AWAY. It'll rev up to screaming even if I let go of the throttle. I have to hit the kill switch.

They will do that, but maybe your L circuit is set a tad lean to begin with, running out of fuel just compounds it.

Or, maybe your fuel line has a pinhole near where it meets the filter.


If those 2 things check out I wouldn't worry at all, controlling a 2 stroke's RPMs is all about controlling fuel/air mixture, when you lose control of one you lose control of the engine.


Chris
 
They will do that, but maybe your L circuit is set a tad lean to begin with, running out of fuel just compounds it.

Or, maybe your fuel line has a pinhole near where it meets the filter.


If those 2 things check out I wouldn't worry at all, controlling a 2 stroke's RPMs is all about controlling fuel/air mixture, when you lose control of one you lose control of the engine.


Chris
I had on old Honda CR250 that had a crack in the intake manifold that wouldn't even stop when you pulled the spark plug wire off! The only way I could get it to stop screaming was to pull the carburetor off the engine. Yeah, you've got an air leak somewhere, better chase it down before you also need a piston.
 
It only does it when the tank is empty, though. The rest of the time there's no sign of air leaks.

Fuel line's new. I'm sure the carb needle settings aren't quite right yet... Whoever had it before me had them totally whacked to compensate for the carb being stuffed full of sawdust.

When I finally got it running reliably it was so fat that it wouldn't 2-stroke. Smoked like a chimney, all fuel.
 
It only does it when the tank is empty, though. The rest of the time there's no sign of air leaks.

Fuel line's new. I'm sure the carb needle settings aren't quite right yet... Whoever had it before me had them totally whacked to compensate for the carb being stuffed full of sawdust.

When I finally got it running reliably it was so fat that it wouldn't 2-stroke. Smoked like a chimney, all fuel.

I guess the only thing to do would be to go through the carburetor and make sure the plunger lever is set in the middle, and adjust the carburetor to the right settings. And make sure you don't run it too low on fuel.
 
when your tank is empty the carb has to pull fuel the farthest, pulling more vacume in the fuel line. probably opens up a small pinhole, allowing air into the line. Just my .02. Is the PM700 solid or have AV? The AV saws have the intake boot, which is a common source for air leaks. That doesn't explain why it leans out on a low tank tho.
 
It could be something as simple as the fuel line is hung up and not resting on the bottom. Or like other suggested, a pin hole in the fuel line somewhere.
 
when your tank is empty the carb has to pull fuel the farthest, pulling more vacume in the fuel line. probably opens up a small pinhole, allowing air into the line. Just my .02. Is the PM700 solid or have AV? The AV saws have the intake boot, which is a common source for air leaks. That doesn't explain why it leans out on a low tank tho.

PM700 is a rigid (non-AV) saw. You may have something there regarding the tank fuel line though Brad...
 
Nah, I wish. I stopped to take those pics and got to talk the property owners. They milled the logs from their own tree farm, found a timber framer to do the actual framing work. The site is a historic roadside Inn and filling station, built in the 20's. The new owners are creating more space for outdoor functons, seminars, weddings, ect. The back patio space is outstanding, with covered bbq space, water features, lot of stone walls and trees in the background. My home-made covered patio is microscopoic by comparison. DS
 

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