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Temp and tuning

Started by luvmexfood, June 04, 2014, 05:34:26 PM

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luvmexfood

Just wondering. My Stihl 029 had it last carb adjustment last November in cold weather. It has gotten where it will not reach peak RPM and just doesn't cut with full power like it was. Bogs down pretty easy. Would the change in temp and humity cause a notable difference. Have a spare fuel filter I will change before I try it again. Not good at tuning but have a source to get it tuned if it needs to be.
Give me a new saw chain and I can find you a rock in a heartbeat.

Ianab

Cold air is denser than warm air. So in cold conditions you would need to richen the mix a little more than in warmer air. Might be enough to notice?

Running too rich also gives the symptoms you describe. Too lean revs like crazy, but with no power, then melts. Too rich just bogs down, but at least it wont destroy itself.

Ian
Weekend warrior, Peterson JP test pilot, Dolmar 7900 and Stihl MS310 saws and  the usual collection of power tools :)

ladylake

 

  By all means saws need less fuel when it's hot outside.  I just ran my Echo CS8000 that was tuned for the winter and it acted like the choke was on until I leaned it out some.   Steve
Timberking B20  18000  hours +  Case75xt grapple + forks+8" snow bucket + dirt bucket   770 Oliver   Lots(too many) of chainsaws, Like the Echo saws and the Stihl and Husky     W5  Case loader   1  trailers  Wright sharpener     Suffolk  setter Volvo MCT125c skid loader

CTYank

If a saw is running too rich, you should be hearing 4-stroking, an exhaust note that sounds like the engine has asthma. Sometimes microscopic pieces of poo lodge in metering restrictions, and turning the needles a fractional turn in one direction and then right back will be enough to knock them loose. These fragments are so small, they get past a filter pretty easily. They will lean the mixture.

Then, when you adjust for optimum H mixture, the saw should 2-stroke (clear exhaust note) @WOT in the cut, transitioning to 4-stroking when you lift (unload it a bit). If you don't get the 2-stroking, lean it. If you don't get the 4-stroking, richen it. In small increments, of course.
'72 blue Homelite 150
Echo 315, SRM-200DA
Poulan 2400, PP5020, PP4218
RedMax GZ4000, "Mac" 35 cc, Dolmar PS-6100
Husqy 576XP-AT
Tanaka 260 PF Polesaw, TBC-270PFD, ECS-3351B
Mix of mauls
Morso 7110

Huskstihl

Keeping your saw in proper tune is very important.  When I am cutting, I will stop and retune for every 5 degree change in temperature.  I also keep an accurate humidity meter, and will retune if the humidity changes by more than 2.5 percent.  I also have an altimeter on my belt, and if my position changes by more than 10 vertical feet, I will also retune.  This makes tree climbing difficult, but in the end it is well worth the trouble

John Mc

Quote from: Huskstihl on June 15, 2014, 12:42:26 PM
Keeping your saw in proper tune is very important.  When I am cutting, I will stop and retune for every 5 degree change in temperature.  I also keep an accurate humidity meter, and will retune if the humidity changes by more than 2.5 percent.  I also have an altimeter on my belt, and if my position changes by more than 10 vertical feet, I will also retune.  This makes tree climbing difficult, but in the end it is well worth the trouble

Don't forget to retune as your fuel ages as well...  maybe every couple of hours? :D
If the only tool you have is a hammer, you tend to see every problem as a nail.   - Abraham Maslow

shiggins

My Dolmar is going well this season. It does seem to get a bit hot when doing a lot of work (Long cuts) after about half  an hour. No stalling though. If it does seem to get a bit hot should i screw the H screw out a bit? I can't hear the 4 stroking everyone talks about but saying that i don't have anyone to show me. I might go into my local and if they have time see if they can show me.

CTYank

Quote from: shiggins on June 16, 2014, 05:19:45 AM
My Dolmar is going well this season. It does seem to get a bit hot when doing a lot of work (Long cuts) after about half  an hour. No stalling though. If it does seem to get a bit hot should i screw the H screw out a bit? I can't hear the 4 stroking everyone talks about but saying that i don't have anyone to show me. I might go into my local and if they have time see if they can show me.

No guess as to where you are, and ambient temps you're dealing with. Saw engines get much more than "a bit hot" when working. Check head temp with IR thermometer sometime- 350-400 F normal. Those temps don't require carb changes.

What is a really good idea, after any extended runtime, no matter the weather, is maybe 20-30 sec @ fast idle for a cool-down. Bit of a warm-up recommended by many experts on startup before running under (full, of course) load.

With everything up to temp, cutting wood, you should hear clear  2-stroking in the cut. When you lift, still @WOT, exhaust note should go "off-song" from excessive momentary richness. That is 4-stroking- may sound like asthma. If you don't hear that, keep richening H mixture in small increments and re-testing, until that happens. Absent that, piston is at risk. That simple.
'72 blue Homelite 150
Echo 315, SRM-200DA
Poulan 2400, PP5020, PP4218
RedMax GZ4000, "Mac" 35 cc, Dolmar PS-6100
Husqy 576XP-AT
Tanaka 260 PF Polesaw, TBC-270PFD, ECS-3351B
Mix of mauls
Morso 7110

Andyshine77

Very good idea to let a saw idle after making long cuts. Idle is the richest setting the saw runs at, so you have alot of fuel to cool the engine down.
Andre.

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