Four stroking “nicely”?

[av8or3]

I just read where a fellow describing how his newly ported saw was four stroking nicely while cutting. It’s my opinion that these saws should NOT be four stroking while cutting. Four stroking means you’re not achieving full power, bunch of unburned fuel will soon be oozing out your muffler onto your saw and you’re clogging your exhaust up with carbon. In an effort to not burn up old saws I will tune so that it will four stroke just as the load is removed (not necessarily only reduced). As a saw heats up I’ve noticed it tends to run a little leaner. I try and have them at full operating temp when I put the final twist on em’ and accept however they run at all air and saw temps after. They run rich if you’re just starting and stopping, but if you’re really running them hard as can be, they’ll be alright. It tells you in the operating manual for the Solo Twin to tune the high screw so it DOES NOT four stroke. It is written as a warning for some reason.
I pay more particular attention setting up the new saws (with their 50:1 mix ratios) using a tachometer just to prevent overspeeding. I’ve noticed there ,that you cannot always count on an overly rich mixture w/o a load at wot. Sometimes the “tone” doesn’t change as the saw bites in on those. I don’t worry myself with that if it comes in at factory specs using a tach.
With the really new saws isn’t it nice not to have to give a shoot? I mean I really like the auto tune and m- tronic saws.
What an I missing on the nicely four stroking? I kinda just rambled on here.

 

[drf256]

If you’re 4 stroking in the cut using intended bar size/raker height/bar pressure the saw needs to be leaned out.

A saw will need a different tune in different ambient temps and load. Sometimes a good tune at the beginning of the cut won’t be the same at the end of a cut because of heat buildup.

I find ported saws with big muffkin mods to be less forgiving in terms of proper tune than a stocker.

As you state above, it is quite nice that AT saws are always at optimal tune. That’s part of why they will usually be quicker through a cut than the same manual tune saw.

 

[Frankavich84]

I just read where a fellow describing how his newly ported saw was four stroking nicely while cutting. It’s my opinion that these saws should NOT be four stroking while cutting. Four stroking means you’re not achieving full power, bunch of unburned fuel will soon be oozing out your muffler onto your saw and you’re clogging your exhaust up with carbon. In an effort to not burn up old saws I will tune so that it will four stroke just as the load is removed (not necessarily only reduced). As a saw heats up I’ve noticed it tends to run a little leaner. I try and have them at full operating temp when I put the final twist on em’ and accept however they run at all air and saw temps after. They run rich if you’re just starting and stopping, but if you’re really running them hard as can be, they’ll be alright. It tells you in the operating manual for the Solo Twin to tune the high screw so it DOES NOT four stroke. It is written as a warning for some reason.
I pay more particular attention setting up the new saws (with their 50:1 mix ratios) using a tachometer just to prevent overspeeding. I’ve noticed there ,that you cannot always count on an overly rich mixture w/o a load at wot. Sometimes the “tone” doesn’t change as the saw bites in on those. I don’t worry myself with that if it comes in at factory specs using a tach.
With the really new saws isn’t it nice not to have to give a shoot? I mean I really like the auto tune and m- tronic saws.
What an I missing on the nicely four stroking? I kinda just rambled on here.

You might want to ask the original poster to what their definition of “nicely 4 stroking”... it may be the same as you they just didn’t take the time to define it in that post. Lots of rambling here lol but anyone is entitled to that!


Sent from my iPhone using Tapatalk

 

[smokey7]

I'm hoping he was meaning it was 4 stroking nicely out of wood or in wood with no pressure. Some saws I run that are old I run them that way where they lightly stroke in wood and clean up while working them good. Also on alot of my stuff the tune leans out a good bit once warm.

 

[1.5hp]

+1 on using a tach. used to think my saws were pretty well tuned. tach said no. now they all run better than ever. on saws with a rev limiter, tachometer is a must.

 

[CR888]

On tools like backpack blower or handhelds that have no clutch and are always under load, I try to tune out near all four stroking right through the rev range, not just at wot but 1/4, 1/2, 3/4 throttle too.

 

[Lightning Performance]

I think saws with a limiter are easier to tune by ear. You can clearly hear the saw hit the limiter. If does not your good. Easy enough to check it hot if your doing a lot of long cuts.

Older saws are easier to ring-out and hurt something imo. They are set pretty rich when it's cold in the wintertime. When someone, "thinks" it runs best... they burn up soon after sometimes Seen that happen as a kid twice lol.

 

[XP_Slinger]

When I set initial tune on a rebuild I check tune in the cut by taking pressure off the chain, most call it lifting. As Al said a safe tune before a cut might not be safe after some heat builds up. That said, a saw should definitely not be 4 stroking while cutting, should clear up.

 

[drf256]

A tach can help, especially on ported saws. It’s a good reference, but not an authoritative tuning device.

I find than many of my ported saws will 4 stroke and clean up in the cut over a pretty broad rpm range. So I will tune differently based upon its use that cutting session.

Case in point, an MS460 I just did for a friend. I tuned it by ear and it was 4 stroking hard at 15500 during its first run. I turned it down to 12800 and it was still 4 stroking and cleaned up with bar pressure. The tach was useful at that point because it gave me some reference point. He isn’t great at tuning and I know this spring I’ll be leaning it out for him.

 

[XP_Slinger]

A tach can help, especially on ported saws. It’s a good reference, but not an authoritative tuning device.

I find than many of my ported saws will 4 stroke and clean up in the cut over a pretty broad rpm range. So I will tune differently based upon its use that cutting session.

Case in point, an MS460 I just did for a friend. I tuned it by ear and it was 4 stroking hard at 15500 during its first run. I turned it down to 12800 and it was still 4 stroking and cleaned up with bar pressure. The tach was useful at that point because it gave me some reference point. He isn’t great at tuning and I know this spring I’ll be leaning it out for him.

Agreed. I use a tach for reference also, but we all know a tach can become a huge distraction if someone focuses on just the numbers. One of those things that can only be overcome through experience I guess.

 

[huskyboy]

One thing I have learned is that if you have a lot of compression (Over 200psi).... and a very open muffler.... start a tad fat on the tune. Lean is not mean for work on a saw with lots of compression. They run hotter and need more fuel than “normal” compression saws to keep them cool. After a few cuts they can lean out quite a bit. You tend to have a more narrow window of a safe tune. It’s one of the few reasons I tend to prefer a saw with below 200-210psi for what I do. But to each his own...

 

[Lightning Performance]

One thing I have learned is that if you have a lot of compression (Over 200psi).... and a very open muffler.... start a tad fat on the tune. Lean is not mean for work on a saw with lots of compression. They run hotter and need more fuel than “normal” compression saws to keep them cool. After a few cuts they can lean out quite a bit. You tend to have a more narrow window of a safe tune. It’s one of the few reasons I tend to prefer a saw with below 200-210psi for what I do. But to each his own...

The answer is Mtronic or Autotune as you know.

Do really prefer a saw over 190psi?...
You just admitted it needs more fuel to cool it and I agree.

Anything much over 175 starts eating more fuel imo. Most of my stuff is 180 or less. A few @190 but I have the luxury of not needing a light fast saw. I just go grab a bigger saw and fill it up. Most of my work is 35-70cc saws. Hardly use the 066 anymore. The others mill.

 

[popopboat]

IMHO its how much you care about your saw and again IMHO tacho method is not most reliable for tuning.

If saw has casting flaw and/or some kind of an air obstruction youll have to lean it out to achieve desired RPM therefore reduce lubrication and its life. (dirty filter maybe too?)
I know this does not happen too often but..

Four-stroking method is superior for durability.
Means that you are giving as much lubrication and cooling as possible and but not interfere with combustion.

Ive used that method since i taught myself to adjust carbs, fourstroking @ no load, twostroking in the cut.
Taking the jug off and cleaning carbon is not too much of a hassle to me so i dont care much about carbon buildup.

just my IMHOs

 

[smokey7]

I totally agree the higher the compression is (close to 200) the tune window when actually working the saw is. Heat changes everything

 

[qurotro]

Why not 32:1? More room for slightly improper tune. With good quality oul, carbon is not an issue.

 

[kneedeepinsaws]

I just read where a fellow describing how his newly ported saw was four stroking nicely while cutting. It’s my opinion that these saws should NOT be four stroking while cutting. Four stroking means you’re not achieving full power, bunch of unburned fuel will soon be oozing out your muffler onto your saw and you’re clogging your exhaust up with carbon. In an effort to not burn up old saws I will tune so that it will four stroke just as the load is removed (not necessarily only reduced). As a saw heats up I’ve noticed it tends to run a little leaner. I try and have them at full operating temp when I put the final twist on em’ and accept however they run at all air and saw temps after. They run rich if you’re just starting and stopping, but if you’re really running them hard as can be, they’ll be alright. It tells you in the operating manual for the Solo Twin to tune the high screw so it DOES NOT four stroke. It is written as a warning for some reason.
I pay more particular attention setting up the new saws (with their 50:1 mix ratios) using a tachometer just to prevent overspeeding. I’ve noticed there ,that you cannot always count on an overly rich mixture w/o a load at wot. Sometimes the “tone” doesn’t change as the saw bites in on those. I don’t worry myself with that if it comes in at factory specs using a tach.
With the really new saws isn’t it nice not to have to give a shoot? I mean I really like the auto tune and m- tronic saws.
What an I missing on the nicely four stroking? I kinda just rambled on here.

I agree works both ways, cant be too lean or too rich well said

 

[FergusonTO35]

I always tune the saw in the sort of wood I expect to cut most with that particular saw. I adjust the high speed screw rich until performance noticeably worsens, then back it off a bit. Check the max rpm with my tach and call it good. Echo 2 strokes do not like to run rich. My CS-400 in particular is chugging and smoking like a hit and miss by the time you get it to 4 stroking nicely.

 

[Red97]

I want it to 4 stroke so hard I can taste it.... out of the wood....