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Tuning for torque

Started by cliffreaves, August 02, 2016, 02:07:53 PM

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cliffreaves

I know I've read it somewhere, but now I can't find it.  If I want to add more torque, do I tune richer or leaner.  My mind seems to get it's wires crossed with higher and low, lean and rich.   I want to be able to dog into a cut without it stalling.  395xp with a big bore and new chain shouldn't stall right?

Jiles

Personally, I think torque is built into the saw. Stihl relies on high RPM where Makita/Dolmar seem to have more torque for the same cc saw.
I have several chainsaws and M/D is my go to saw when heavy cutting is required.
If the saw is tuned to "fourstroke" out of cut and not in cut, and the drive sprocket is sized right for saw and type chain, it is probably doing all it can.
Satisfy needs before desires

John Mc

When a saw is tuned to "four-stroke" out of the cut, it is actually running a bit on the rich side. Tuning it just enough rich to four-stroke out of the cut, and clean up in the cut is generally where you want to be. You certainly don't want to be so lean that it bogs down in the cut.

FWIW, the best performance mod you can do is a well-sharpened chain.
If the only tool you have is a hammer, you tend to see every problem as a nail.   - Abraham Maslow

ZeroJunk

If you have a suitable log you can do timed cuts. Tweak your mix for the fastest time and supposedly that is as in tune as you can get. I always tune mine richer than the fastest cutting speed because getting the last ounce of speed out of it means nothing to me. And, it's safer in case you get some bad gas or something.

HolmenTree

My opinion the only proper way to get more torque out of a chainsaw, is to lower the "gear ratio" at the drive sprocket.  That is run a smaller drive sprocket.

Back in the day gear transmissions were a very reliable way of producing extra torque. .....
Making a living with a saw since age 16.

John Mc

Quote from: HolmenTree on August 02, 2016, 09:46:56 PM
My opinion the only proper way to get more torque out of a chainsaw, is to lower the "gear ratio" at the drive sprocket.  That is run a smaller drive sprocket.

Yeah, but that assumes it's running properly in the first place.
If the only tool you have is a hammer, you tend to see every problem as a nail.   - Abraham Maslow

cliffreaves

I understand what you guys are saying.  In my case my saw was able to be dogged in until I tried to tune it myself.  My biggest struggle was getting the idle set low enough that chain would stop moving while idling. I turned the high and low down a bit as well because I thought it was screaming a bit too much.  Now I'm just trying to get it closer to where it was before I messed with it and without messing it up more.  I think I'll try John's idea tomorrow.

John Mc

If the only tool you have is a hammer, you tend to see every problem as a nail.   - Abraham Maslow

cliffreaves

That's exactly what I needed John, thanks again!

ZeroJunk

The saw will be four stroking no load anywhere it is not too rich to run below somewhere around 13,000 RPM.  I have tuned them after repairs and they seemed to be running fine to me and after checking with a tach they were only turning 10,500 no load WOT. Doesn't exactly jump out at you.

ladylake

 Too lean they will bog easy, keep in mind even the biggest saw will bog with enough pressure on a good sharp chain.  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

SawTroll

Quote from: cliffreaves on August 02, 2016, 02:07:53 PM
I know I've read it somewhere, but now I can't find it.  If I want to add more torque, do I tune richer or leaner.  My mind seems to get it's wires crossed with higher and low, lean and rich.   I want to be able to dog into a cut without it stalling.  395xp with a big bore and new chain shouldn't stall right?

As far as I know, the engine will make the most torque all the way trough the rpm range when the carb is correctly tuned - not lean and not rich.

If you want to change where in the rpm range there are as much torque as possible you likely have to change the cylinder porting, even though there also is other factors that contribute to "how high" the torque curve generally will be (carb size and how open the muffler is are exemples).

Unless you are using a saw that really is too small for the task at hand, it generally is best to have the peak torque as close below max power rpm as possible (very close isn't possible, so there is no risk that it comes too close). The point is to have torque backup, to keep the rpm in the max power range when the wood is large enough that the rpm isn't higher.
Information collector.

DelawhereJoe

What size b/c are you running on the saw and is the chain full comp, half or full skip ? Also what type and size wood do you have it into ?
WD-40, DUCT TAPE, 024, 026, 362c-m, 041, homelite xl, JD 2510

cliffreaves

I usually run a 24" bar full comp.  It did fine until I "tuned" it.  I think the saw can handle it, and it's just user error.

RIDE-RED 350r

ANY saw can be force-fed more than it can handle, no matter how big or powerful.

State of tune is very important, but so is cutting technique. A saw won't readily eat oak as fast as it can eat the same sized hemlock. The hardness (species) and dryness of the wood plays a significant role. If you try to dog it in and push it too much for the type/condition of the wood, it will bite and slip the clutch.

Now if all of the above are addressed and as they should be, a base gasket delete is a relatively simple mod that increases grunt. I have done this on a couple 394 with success and no need for milling... I assume that the 395 would be suitable for this mod as well. It may lose a pinch of top RPM, but it gains in torque and throttle response.
Swedish, you know, like the chef.

cliffreaves

I played with the tuning tonight and got it back to where it easily cuts cookies without bogging even when dogged into the cut.  It took me about an hour to get it where I like.  I think I will get a new bar and a skip chain though.  My 24" bar is still jacked even with a new chain it still quite cutting once the bar is buried.  The saw cuts better by far with my 36" bar right now.  Thanks again guys.

John Mc

Quote from: cliffreaves on August 03, 2016, 10:13:17 PM
... I think I will get a new bar and a skip chain though.  My 24" bar is still jacked even with a new chain it still quite cutting once the bar is buried.  The saw cuts better by far with my 36" bar right now.  Thanks again guys.

Try the Pferd Universal Edge Sharpener on that bar (I linked to it in another thread you started). It does sound as though your bar is worn unevenly and needs to be trued back up.
If the only tool you have is a hammer, you tend to see every problem as a nail.   - Abraham Maslow

SawTroll

Quote from: John Mc on August 03, 2016, 10:24:45 PM
Quote from: cliffreaves on August 03, 2016, 10:13:17 PM
... I think I will get a new bar and a skip chain though.  My 24" bar is still jacked even with a new chain it still quite cutting once the bar is buried.  The saw cuts better by far with my 36" bar right now.  Thanks again guys.

Try the Pferd Universal Edge Sharpener on that bar (I linked to it in another thread you started). It does sound as though your bar is worn unevenly and needs to be trued back up.

If that is the same thing that Stihl sells (that one is made by Pferd) it basically is useless for anyone that has the slightest knowledge of how a saw chain should be filed - but it may be an option for those that know nothing about that, and only use semi-chisel chain.

The "thing" rides on the cutters on both sides of the cutter (and raker") you file, which will mess those cutters up, at least if it is a chisel chain. Then the raker part of it obviously doesn't work progressively, so the rakers always will be left too high on chain that is used, and the cutters filed back.
Information collector.

cliffreaves

I will try that first John.  Thanks again!

cliffreaves

Sawtroll and I posted at the same time.  Are you saying I should try something else, or not try it at all? From what I can see, the item that John suggested is basically an easy way to even up a bar that's worn unevenly.   Nothing to do with the chain unless I'm mistaken.

HolmenTree

Cliffreaves,  I own a 395XP and it came from the factory with the smallest diameter 3/8" rim sprocket. ...a 7 tooth with a 32" bar.  Again as I previously said lower gearing produces torque.
Sounds like you may have a pressure leak like a bad crankshaft seal or dried up carb diaphragms.
The 395 has carb high and low setting screw limiters so I can't  see where you can run it too lean.
Pretty well fool proof with intact  limiters if your saw still has them.
The Pherd or Stihl 2 in 1 filing guide is a good setup don't let SawTroll sway you. A good tool for the novice. Keep sharp files in it and your good to go.
Making a living with a saw since age 16.

HolmenTree

Quote from: cliffreaves on August 03, 2016, 11:28:22 PM
Sawtroll and I posted at the same time.  Are you saying I should try something else, or not try it at all? From what I can see, the item that John suggested is basically an easy way to even up a bar that's worn unevenly.   Nothing to do with the chain unless I'm mistaken.
Hahaha, now we're speaking 3 different languages. Bar dressers and file guides from 3 different opinions.
Making a living with a saw since age 16.

cliffreaves

Yeah, probably my fault.  I started talking about my bar in a chain sharpening post, then I started talking about it again in a tuning post.🙃  I have trouble staying on topic even when I bring it up.😂

HolmenTree

Not a problem on Forestry Forum . Everyone may slip time to time but the beauty of this forum is negatively is kept low key. Great bunch in the community here willing to share their experiences.  :)
Making a living with a saw since age 16.

John Mc

Quote from: SawTroll on August 03, 2016, 11:25:15 PM
Quote from: John Mc on August 03, 2016, 10:24:45 PM
Quote from: cliffreaves on August 03, 2016, 10:13:17 PM
... I think I will get a new bar and a skip chain though.  My 24" bar is still jacked even with a new chain it still quite cutting once the bar is buried.  The saw cuts better by far with my 36" bar right now.  Thanks again guys.

Try the Pferd Universal Edge Sharpener on that bar (I linked to it in another thread you started). It does sound as though your bar is worn unevenly and needs to be trued back up.

If that is the same thing that Stihl sells (that one is made by Pferd) it basically is useless for anyone that has the slightest knowledge of how a saw chain should be filed - but it may be an option for those that know nothing about that, and only use semi-chisel chain.

The "thing" rides on the cutters on both sides of the cutter (and raker") you file, which will mess those cutters up, at least if it is a chisel chain. Then the raker part of it obviously doesn't work progressively, so the rakers always will be left too high on chain that is used, and the cutters filed back.

SawTroll - I think you misunderstood what I was talking about. I think you were ranting about the depth gauge tools - and I completely agree with you, the style that rests on a couple of teeth with a dropped part for the depth guage to poke through is far from an optimum solution (we've had this conversation before, agreed 100%, and I won;t go back into it in any depth here, unless the OP has an interest in it.)

When I was talking about the Pferd Universal Edge Sharpener, I was referring to their bar rail dresser, which squares up and deburrs bars. It has nothing to do with sharpening chains. Yes, you can use a belt sander with a jig to hold the bar square, but not all of us have access to those, and the Pferd tool gives excellent results for $24 from forum sponsor Comstock Logging Supplies (who incidentally also happens to have the best price I could find on this tool). Unfortunately, the picture below shows the non-working side of the tool or it is incorrectly assembled. It is designed to hold the file at 90˚ to a "plastic shelf" that rides on the bar as you deburr & square it.)

If the only tool you have is a hammer, you tend to see every problem as a nail.   - Abraham Maslow

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