Can you tune a saw without a bar and chain AND no wood?

[watsonr]

Like many of you, I'm seeing a lot of burned up saws across my bench. A good portion are just old and worn machines that get taken care of poorly. You can tell that by the faded plastics, owner say it sat for years and so on....

Most of this stuff is being used with some sort of regularity, but the quality of fuel in today's economy is something to be desired... bringing me to the question.

Can you tune a saw with some degree of accuracy without a bar and chain attached.... AND never taking the saw to the wood pile.

I'm very good friends with my dealer, they buy aftermarket parts from me to save there repair service based customers money when they can with permission from the customer of course. They are now keeping some customers that would have normally walked out the door by offering a reduced repair bill. Great on them and I've heard nothing but good things from those customers.

I watched them tune a saw the other day with no bar and chain, used a tach to set the saw to the correct RPM. I'll assume that once the bar and chain are installed that the RPM will be reduced and then the wood test would reduce it further.

Would this be in fact true.... that saw should be plenty rich for use?

 

[Adirondackstihl]

1st I heard of anyone tuning like that. Not good practice IMO.
I would almost think the saw would be too rich afterwards.
But if youre gonna err.......err on the rich side.

I just don't like the idea of the "free rev"..........

 

[nmurph]

I've checked plenty of 346's with a B/C and no load, and without a B/C, and there isn't an appreciable difference in the WOT rpm's. IMO, a B/C doesn't put much load on a saw unless you are going way past the normal B/C lengths for a given saw.

 

[nmurph]

I've checked plenty of 346's with a B/C and no load, and without a B/C, and there isn't an appreciable difference in the WOT rpm's. IMO, a B/C doesn't put much load on a saw unless you are going way past the normal B/C lengths for a given saw.

 

[blsnelling]

The chain certainly isn't much load, but I wouldn't do it. Nothing but short blips without the B&C for me.

 

[Chris-PA]

A carb does not respond directly to load at all, it only responds to the velocity of air going through the venturi. The load just reduces the rpm it can turn. Given the way traditional (non-AT/MT) carbs work, the mixture gets richer as the air velocity increases - much richer, causing misfire with just a modest increase and eventually limiting the max rpm it will spin. This is the way they specify the mixture - if you set it so the terminally rich mixture limits the rpm to the factory spec, then it will be right at the lower rpm (& air velocity) in the cut. But that relationship is only true for an unmodified saw.

So with a stock saw if you can adjust it to the factory WOT rpm setting with the H screw it will be correct.

 

[o8f150]

I am with brad on this one

 

[naturelover]

Watch out for the clutch too...


Sent from my iPhone 5 using Tapatalk

 

[blsnelling]

Watch out for the clutch too...

That's no joke! I had one bounce off the hood of my van once

 

[tlandrum]

if your adjusting a carb for no load wide open rpm with a tach the bar and chain are not needed but id not do it without the clutch cover on. I had a clutch disappear like a wild rabbit hopping thru the tall crass once. all you could see was it hop up out of the grass every few feet.

 

[watsonr]

What I thought, thanks fellas!

 

[chrisoppie]

i might, might, adjust the low and the idol with out the bar and chain on.

 

[Arrowhead]

I'd never do it. I've ran them with no b/c just to get a close setting.
I'd never call a saw 100% tuned until I had it in some wood.

 

[Chris-PA]

I'd never do it. I've ran them with no b/c just to get a close setting.
I'd never call a saw 100% tuned until I had it in some wood.

I agree - adjusting the saw at some max rpm where the mixture is so rich the saw won't rev any higher as a way to set mixture at lower speeds seems kinda hokey. It's just a first-pass guess to me.

 

[CTYank]

I agree - adjusting the saw at some max rpm where the mixture is so rich the saw won't rev any higher as a way to set mixture at lower speeds seems kinda hokey. It's just a first-pass guess to me.

I've seen a couple self-appointed dealer geniuses demonstrate that their guess was nowhere close, on my RedMax GZ4000. Should've reported them to the EPA (who they invoked for cover.) Both of them gave the saw back with stinky-rich high-speed a/f, so rich that the 4-stroking under load could not be missed. Whatever the last one did, I could then adjust the carb myself, ended up turning the high-speed screw in about 3/4 turn.
That done, it sings cleanly under load, and makes a proper transition to 4-stroking. Once again, it punches well above its weight. Love it.
Adjusting by tach, to me, is a total waste of time, recourse of fools.

 

[Frogfarmer]

Here's a thought. What if the saw runs fine with no BC but developes an air leak with BC. I have an 026PRO under the bench right now that runs fine with no BC but has the typical clutch side seal leak and wont stay tuned with a BC attached. I call BS doing this with no BC and expecting a saw that is ready to cut. I have never tuned a saw without BC and dont intend to start.

 

[Chris-PA]

I've seen a couple self-appointed dealer geniuses demonstrate that their guess was nowhere close, on my RedMax GZ4000. Should've reported them to the EPA (who they invoked for cover.) Both of them gave the saw back with stinky-rich high-speed a/f, so rich that the 4-stroking under load could not be missed. Whatever the last one did, I could then adjust the carb myself, ended up turning the high-speed screw in about 3/4 turn.
That done, it sings cleanly under load, and makes a proper transition to 4-stroking. Once again, it punches well above its weight. Love it.
Adjusting by tach, to me, is a total waste of time, recourse of fools.

OTOH I think that setting the mixture to a specific WOT rpm is the factory procedure for mixture adjustment for some brands/saws. What your mechs did must have just been something else!

The best analogy is that of shooting a bow a long distance, or anything with a lot of drop. As long as all conditions stay the same, you can count on aiming at a point way high of the mark and still hit it. The point you aim at represents WOT max rpm, and is otherwise meaningless. And of course if something changes (lighter arrow, bigger bow, distance to target, etc.), that aim point is now irrelevant. And there are many things that can change in saw tuning!

Here's a thought. What if the saw runs fine with no BC but developes an air leak with BC. I have an 026PRO under the bench right now that runs fine with no BC but has the typical clutch side seal leak and wont stay tuned with a BC attached. I call BS doing this with no BC and expecting a saw that is ready to cut. I have never tuned a saw without BC and dont intend to start.

But in fairness the saw is broken, so it is not really a tuning issue.

 

[CR888]

l agree with Brad and l like Terry's rabbit analogy...funny. However stihl dealers in my area get your new saw, take it out the back, start it and b4 shes warmed up have it screaming so they can tune it. I understand you can tune with a tach and no wood and all but l cringe hearing a new P&C doing 14k+ COLD. l insisted that l tune my saw on my next purchase.

 

[Stihl working hard]

The chain certainly isn't much load, but I wouldn't do it. Nothing but short blips without the B&C for me.

What a scarey thought no b&c at wot couldn't agree more just blip the throttle

 

[nmurph]

I've done enough to know it isn't a problem and yields very good results. Sure, I check the tune when I get it into wood, but I do that with all saws as they are run throughout the day.