New Tach and Tach tuning

[Log Hogger]

"Tach tuning" is something I'm not comfortable with. A stock saw may come with a maximum RPM specification, but due to manufacturing variances that specification is only a guideline. Tuning ONLY with a tach could result in a saw on the edge of a lean seize. I have a tach and use it, but the final adjustment is always determined by the behavior of the saw in the cut. I like a saw to four stroke with only a little gentle lifting of the bar in the cut, which I've found also seems to give the most power.

 

[mtngun]

But don't the factory spec go out the window once a saw has been modified...otherwise whats the point...

The point is more power in the cut, typically at 8000 - 10,000 rpm.

Tuning ONLY with a tach could result in a saw on the edge of a lean seize.

I've never heard of anyone on AS claim that they seized a saw by tuning it to factory spec.

 

[WidowMaker]

The point is more power in the cut, typically at 8000 - 10,000 rpm.


I've never heard of anyone on AS claim that they seized a saw by tuning it to factory spec.

===

So are we saying that factory specs should be followed, even after mods, not arguing, just trying to learn...

 

[Agoraphobia]

Only as a baseline. Do you know of any reasonable deliberate mods that would cause a lean condition at the factory spec?

 

[Iron Head]

Is it just me or the toggle button pad is difficult to push?

 

[Beer Gut]

Is it just me or the toggle button pad is difficult to push?

yes mine is a little you got to get it in the right spot

 

[rbmopar]

yes mine is a little you got to get it in the right spot

That's what she said.

Sorry, I couldn't pass that one up

 

[Log Hogger]

The point is more power in the cut, typically at 8000 - 10,000 rpm.


I've never heard of anyone on AS claim that they seized a saw by tuning it to factory spec.

Dolmar 5100S

 

[Nitroman]

Might be a stupid question but I'm new to saws and 2 stroke engines. But how does using a tach tell you the engine is running rich?

A tach is a reference tool.

You can start your saw tune by turning it so rich it runs poorly, then while holding down the throttle adjust the screw to lean it out. As it leans out the rpms rapidly climb. When you are on the edge of 2-stroke and 4-stroking, it is very easy to hear the difference (Note: Mandatory to use earplugs and earmuffs, any who do not are stupid). Once the saw is adjusted lean enough, it really sounds "clean". When you think it is good, look at the tach. Should be right there.

I think using tach is excellent for folks who have difficulty with tuning, or simply not enough experience, because when those 100cc saws start turning up over 12k, many might believe they are getting too lean and/or frightened by the symphony, and not take it to the correct rpm level.

 

[Nitroman]

This fits here, so I'll ask:
Do I have this correct

Need to richen when: O2 density increases, so at Sea Level or lower elevation, On dry days (low humidity), and when cold.

Need to lean when: O2 density decreases, at higher elevations, at higher humidity levels, when hot.

So if a rank amateur was going to tune once for the season they would be much better off tuning at the lowest altitude they will cut at, on a dry (low humidity) day that is as cold as they are likely to cut on. That way they are at the conditions that require the richest settings and seasonal fluctuations shouldn't phase them or ruin their saw.

Where as if they tuned at high elevation on a hot, humid day, they risk running lean when any or heaven forbid all three conditions change?

Do I have that right? I don't intend on actually doing this (only tuning once for the season), but I want to make sure I understand the variables correctly.

Once you've tuned a few times, it is so easy and quick you'll find yourself doing it without thinking every time you go out to the woods.

Southeast huh? Man I feel for you. I hated Southeast.

 

[Log Hogger]

I think using tach is excellent for folks who have difficulty with tuning, or simply not enough experience, because when those 100cc saws start turning up over 12k, many might believe they are getting too lean and/or frightened by the symphony, and not take it to the correct rpm level.

The problem is tuning a saw isn't a set it and forget it sort of thing. If someone doesn't know how to tune and uses a tach to set max rpms, then they might not recognize when the saw goes out of tune due to an air leak or fuel supply problem.

 

[MacLaren]

Thats a good tach. I got one of them too from edge and engine. I believe they are a site sponsor too.

I agree. Edge and Engine are fantastic. Super fast shipping as well.

 

[Beer Gut]

I would think your ear would be more of the referance tool, who can hear 13,500 rpm's on the head knowone, but you can hear a specific sound (4-stroking) that tells you are in the ballpark. Being able to ear tune can still leave you hundred's of rpm's off. Today I retuned my 044 after finishing dual port mod I let the saw warm up and I tach tuned, then I cut for awhile then I tach tuned, then I cut some more and tuned again. After that the saw didn't change anymore. I let it cool and started again it ran rich at first and after a few cuts and warming up it leaned right back to 2,700 idle 13,500 WOT, at the same time I was listening to the saw. I guess its what you are comfortable with.