chainsaw technique

[foodforests]

I have been using my bosses chainsaw clearing brush. He came up to me the other day while I was cutting and told me that I was revving it too high. He asked me to tease the trigger a bit more when cutting smaller stuff. He actually said that I should only pull till about half the maximum revs when cutting smaller stuff. He said that the high pitched whine he hears when I use the saw means that I am hurting the engine.
I can see his point that I shouldn't run the saw at full throttle when I'm not cutting anything, but had always thought that it was better for the saw to run it at full throttle when actually cutting. I have read somewhere since our discussion that cutting smaller material at lower revs increases the likelihood of kickback and other mishaps.
What do you guys think/do?

 

[pinus]

IMO, if the engine load is small. The keeping half-throtle and rpms down is normal and rather good for engine. Cutting at heavy load at half-throtle, that can hurt engine

 

[t_andersen]

I agree with Pinus and your boss.

 

[sawn_penn]

I've never seen a manufacturer say anything but "always cut at full throttle"

 

[Jim Mesthene]

I've never seen a manufacturer say anything but "always cut at full throttle"

I thought that was the universal rule. It says that in all the instruction manuals.

 

[Lakeside53]

I thought that was the universal rule. It says that in all the instruction manuals.

...but that's for cutting wood, not brush. The idea is to apply full throttle then let the cutting keep the rpm down. You can't do that on small stuff as the saw has too much HP... You still have to be able to control your rpm.

Reality - you should be using a much smaller saw on brush, or a brush cutter.

 

[carvinmark]

I tickle the triger to keep rpm's down,I have to pay for repairs myself,THINK ABOUT IT!!!!

 

[toolmaker]

My Stihl delaer says to run all two-strokes "WFO".

 

[Lakeside53]

My Stihl delaer says to run all two-strokes "WFO".

he's right, but he's wrong in the case of a saw with too much power for the job, and no internal rev limiting.

 

[spacemule]

Here's what one the more knowledgeable ex members had to say on the subject:

Well actually depending on what carb your saw has, there could be harm to your engine running for extended periods at partial throttle. Many, if not most diaphragm carbs have no mid range fuel circuit. They have a lo speed and a high speed circuit that begins to supply fuel at a higher vacuum. The area between these two ranges is not precisely metered.

It`s my belief that this is why so many carvers and log home builders who "sweep" with their saws have such a high failure rate.

On the other hand, bumping knots with the throttle pinned is also bad.

Russ

 

[Lakeside53]

yes, Jokers is right - partial power is bad in many saws, but so is WOT, so there's a trade off. In any case, cutting brush isn't running partial power for long periods - usually short gunning bursts, much like with limbing small branches.

 

[spacemule]

yes, Jokers is right - partial power is bad in many saws, but so is WOT, so there's a trade off. In any case, cutting brush isn't running partial power for long periods - usually short gunning bursts, much like with limbing small branches.

So, you're saying you don't continuously hold the throttle at half, but gun it and let it "coast" through the limb? I could go for that.

 

[clearance]

yes, Jokers is right - partial power is bad in many saws, but so is WOT, so there's a trade off. In any case, cutting brush isn't running partial power for long periods - usually short gunning bursts, much like with limbing small branches.

Yes, exactly what I do. Years of slashing powerlines, limbing little trees with 60-70cc saws. Never let it scream, never let it bog. Stihl dealers seem to razz the snot outta new saws wot, seen it myself buying new saws, made me cringe, heard about it from others and here. Why?

 

[spacemule]

If I'm not mistaken, you have to have the saw wide open to accurately set the high speed mixture.

 

[pinus]

On large Husq brushcutters-clearing saws are the possibility to fix (limit) max throtle range between the max-half (speed regulator knob). There is no big difference between saws and brushcutters engines.
Physics will do the job. The inertial forces are growing with rpms and the wearing speed too.

 

[foodforests]

Thanks for the respoonses... I'm glad my boss isn't wrong. I kinda like him.

 

[SawTroll]

So, you're saying you don't continuously hold the throttle at half, but gun it and let it "coast" through the limb? I could go for that.

BINGO!

 

[rbtree]

What I learned, from the saw gurus on this board, is to not run a saw at partial throttle as most carbs don't have metering jets that work correctly at partial throttle, so it is possible to crete a lean condition, which of course is not a good thing. So, blipping the throttle is the way to go when you can't keep the rpm in the power band. Continued cutting at peak rpm could likely do more damage to a saw, though.

Here's the thread where the discussion took place...thanks Jokers!!

http://www.arboristsite.com/showthread.php?t=25472&highlight=half+throttle