272 xp won't pull a load

[blowfo356]

Used it two weeks ago and ran fine, loaned to my dad and he put in 16 to 1 mix.
I drained and refueled with 50 to 1, will not hold rev or pull load / cut.
What's the problem? He feels bad and wants to take it to the shop, I'm guessing it's something easier than that.

Any help is appreciated.

Ken

 

[trophyhunter]

Used it two weeks ago and ran fine, loaned to my dad and he put in 16 to 1 mix.
I drained and refueled with 50 to 1, will not hold rev or pull load / cut.
What's the problem? He feels bad and wants to take it to the shop, I'm guessing it's something easier than that.

Any help is appreciated.

Ken

A good dose of 16:1 mix could very well have gotten the P&C pretty hot if it was tuned for 50:1, remember it's the fuel not oil that cools. Check compression numbers, if low pull the muffler see if that piston donated some of it's skin to the cylinder walls. You can check and see if the rings are free while the muffler is off as well.

 

[blowfo356]

A good dose of 16:1 mix could very well have gotten the P&C pretty hot if it was tuned for 50:1, remember it's the fuel not oil that cools. Check compression numbers, if low pull the muffler see if that piston donated some of it's skin to the cylinder walls. You can check and see if the rings are free while the muffler is off as well.

Great compression, still idles and revs to half to 3/4 throttle then falls flat on its face, will even stall out fully if throttle is not released quickly enough.

 

[514mach1]

I'd change fuel filter and try to run it for a bit. Also I'd count the turns to lightly seat the high side carb screw and then screw it back out to where it was (should be around 1.5 turns). Spark plug still look mostly clean?

 

[z71mike]

Pull the muffler and see how gunked up it looks inside. You may also have a clogged screen in the muffler and carb. It was running sludge.

 

[514mach1]

^ I can't believe I didn't think of that. And some of my saws still have muffler screens too. :redface:

 

[blowfo356]

^ I can't believe I didn't think of that. And some of my saws still have muffler screens too. :redface:

We will try both of those things, thanks for some pointers.

 

[trophyhunter]

Great compression, still idles and revs to half to 3/4 throttle then falls flat on its face, will even stall out fully if throttle is not released quickly enough.

What's it pumping up to? It's one thing to pull the rope and have it feel like "great compression" and another matter altogether to test it first and then pull the muffler if readings are low to discover eveythings scored so badly it's just a grooved piston dragging the cylinder wall.

 

[blowfo356]

What's it pumping up to? It's one thing to pull the rope and have it feel like "great compression" and another matter altogether to test it first and then pull the muffler if readings are low to discover eveythings scored so badly it's just a grooved piston dragging the cylinder wall.

I'll have to put a gauge on it, no comp valve on this one - pulled every bit as hard as before... will also pull the muffler and give a look, too bad work gets in the way of tinkering.

 

[rupedoggy]

A good dose of 16:1 mix could very well have gotten the P&C pretty hot if it was tuned for 50:1, remember it's the fuel not oil that cools. Check compression numbers, if low pull the muffler see if that piston donated some of it's skin to the cylinder walls. You can check and see if the rings are free while the muffler is off as well.

Really???????????:msp_rolleyes:

 

[Cloud IT]

My guess is that the screen is gooped up blocking airflow. Take it off and see if letting it breathe will help.

I can't think how running 16:1 for a little bit would harm anything. I bet she was smokin!

 

[trophyhunter]

Really???????????:msp_rolleyes:

I take it you disagree that fueling a saw tuned to run @ a 50:1 ratio with fuel mixed at 16:1 immediately creates a lean running condition, thereby turning the P&C into a crispy critter if run long enough? opcorn:

 

[ncfarmboy]

Can't go by feel on compression this model will fool you ask me how I know. Tillotson RK23HS carb kit if piston and cyl are good.
Shep

 

[rupedoggy]

I take it you disagree that fueling a saw tuned to run @ a 50:1 ratio with fuel mixed at 16:1 immediately creates a lean running condition, thereby turning the P&C into a crispy critter if run long enough? opcorn:

Someone has sold you a bill of goods. You may think logically this makes sense. Try it! I have, and you are wrong. If gas cools the engine, try running no oil and see if it melts the piston to the cylinder no matter how rich you tune. More oil does not cause melt. The old saws ran on 32,25 and 16 to one. Take an old one apart and see the piston is still good. The new 50:1 saws come into my brothers shop everyday...... melted!! Mike

 

[walexa07]

Someone has sold you a bill of goods. You may think logically this makes sense. Try it! I have, and you are wrong. If gas cools the engine, try running no oil and see if it melts the piston to the cylinder no matter how rich you tune. More oil does not cause melt. The old saws ran on 32,25 and 16 to one. Take an old one apart and see the piston is still good. The new 50:1 saws come into my brothers shop everyday...... melted!! Mike

Those older saws were tuned for that ratio. Tune one correctly for 50:1 mix, then change the mix to 16:1 and it could very well seize. This has been discussed many times and I have witnessed it myself. I changed to 32:1 from 50:1 and had to slightly adjust most carburetors. The most obvious signs to me are on the low side - after changing to a richer mix ratio some saws will stumble as if lean and/or die while idling, requiring richening up the low jet. Most of my saws are typically tuned rich enough on the high side that they are still rich enough with a heavier mix so not retune typically required there.

Something else that comes into play here is how well the oil burns. Some petroleum oils actually combust more like fuel and are of less consequence (tuning not impacted enough to notice). Other oils such as the full synthetics do impact the tuning and saw must be retuned.

I agree that more oil lubricates better - but with a heavy enough mix there is less gasoline there to burn, effectively creating a lean condition no different than leaning your saw out through carburetor adjustment.

Waylan

 

[514mach1]

I think the 16:1 vs 50:1 tuning issue isn't so much a matter of oil taking up volume as the fuel is metered through the carb (causing lean or rich as far as total amount of gasoline available) so much as the 16:1 mix probably doesn't atomize, and therefore efficiently combust, as well as the 50:1 mix. This failure to fully burn as much of the fuel available as the 50:1 mix acts the same as too little fuel. As in, there's probably enough gas going into the cylinder to not cause a dangerously lean condition but if some of that gas isn't getting burnt because it has too much oil with it, it's the same as that gas never being there in the first place. I'd think a saw would have to be tuned very close to "the edge" with 50:1 for 16:1 to cause it to burn up due to the oil displacing gasoline as it's metered out from the main jet.

 

[walexa07]

I think the 16:1 vs 50:1 tuning issue isn't so much a matter of oil taking up volume as the fuel is metered through the carb (causing lean or rich as far as total amount of gasoline available) so much as the 16:1 mix probably doesn't atomize, and therefore efficiently combust, as well as the 50:1 mix. This failure to fully burn as much of the fuel available as the 50:1 mix acts the same as too little fuel. As in, there's probably enough gas going into the cylinder to not cause a dangerously lean condition but if some of that gas isn't getting burnt because it has too much oil with it, it's the same as that gas never being there in the first place. I'd think a saw would have to be tuned very close to "the edge" with 50:1 for 16:1 to cause it to burn up due to the oil displacing gasoline as it's metered out from the main jet.

Well going from 50:1 to 32:1 in my 346xpNE caused it to be significantly lean on the low speed side. It kept acting like it was running out of fuel and would bog pretty bad accelerating. Prior to that it throttled up perfect. If I continued to run it lean on the low side I would not be surprised if some damage could occur. If I would have gone from 50:1 to 16:1 it would have been even worse. If it can make that much difference on the low side going from well-tuned to acting up pretty good - I can believe that one tuned well on the high side could do the same - except on the high side it would be easier to miss if someone wasn't accustomed to listening for burble as the power output could still be strong.

From the sound of this particular I do not think engine damage has occurred, rather it is more probable that the screen or muffler is clogged, or excessive carbon has built up in the exhaust port.

Waylan

 

[trophyhunter]

Someone has sold you a bill of goods. You may think logically this makes sense. Try it! I have, and you are wrong. If gas cools the engine, try running no oil and see if it melts the piston to the cylinder no matter how rich you tune. More oil does not cause melt. The old saws ran on 32,25 and 16 to one. Take an old one apart and see the piston is still good. The new 50:1 saws come into my brothers shop everyday...... melted!! Mike

I hope your not turning wrenches in that shop. Those "old" saws were specifically tuned for those denser oil to fuel ratios, and it seems everyone here has a basic working knowledge regarding the necessity of proper tuning to avoid a lean out condition except you.

Whatever, burn your own stuff up but don't parrot misinformation for people looking for help.

 

[HuskStihl]

The size of the carb jets are selected for the amount of oil in the mix. 50:1 will flow just fine through a jet that 16:1 will gum up. A modern saw will run on 16:1, but you'd have to enlarge the passages. If you just run it, it will smoke like crazy and be hot 'n lean at the same time

 

[HuskStihl]

I still bet it's the arrestor screen or plug, at least I hope so:msp_biggrin: