Tuning Saws for Seasons

[rarefish383]

I often read where guys tune saws with the change of seasons. When I raced cars we kept logs of temp, barometric pressure, humidity, and tuned the carbs appropriately. But, in 50 years of commercial tree work, and with 4 other family members owning tree companies, I have never, nor know of any other commercial companies, that tune on a daily, or seasonal basis. We always had extra saws on the trucks and if one went down, you grabbed another and went back to work. I have at least 6 saws on my shelves that Dad bought new in the 70's and early 80's that I can grab and will start and perform as expected. I know that in the last twenty years I've never touched a carb, and the last GTG I went to, the only remark on my Super 1050 was, "that thing needs more bar!" It now wears a 45". I bought a new 660 8-10 years ago to mill with, and have never touched the carb. Carbs scare me. I can take a saw that runs well and make it run bad, and take one that runs bad and make it not run at all. When I say Dad would drop them off at the shop, that was not a common event. Most of our saws never went to the shop for more than periodic maintenance. So, I guess my question is, "are the guys that tune for change in weather, etc, using their saws for commercial service, or trying to ring out the best performance under every condition. When we tuned a race car on race day, that was for peak performance that day, that hour. I only tune my vehicles per the maintenance schedule. Can some guys be "over" tuning, where they should let it be?

 

[Harmon]

When it gets real cold here you might need to make some carb adjustments, a saw that ran great in september might not like minus 20 degrees F and mixed fuel leftover from the fall (probably got some water in it somehow, which is now ice...) but some minor fiddling and fresh mix back in business. Here they sell winter blend gas which has got some different ingredients in it. That and when the air is real cold it is more dense = more oxygen. So if you make no adjustments yr saw will run lean or just not run. I am not a huge fan of the computer carb on the ms 362c but when its cold cold and the way to stay warm is keep working, having to f around with a tiny screwdriver (dont drop it in the snow!) is not my idea of fun.

That being said, do you have winter in MD?

 

[ericm979]

I tune the carb when I think the saw's too lean or too rich, based on how it is performing. I can hear it when it's too lean or too rich. It ends up being about twice a year but it's not something I keep track of. Most people in the middle to northern US have wider temp variations than we do here relatively close to the ocean and might find it more necessary. I generally do not move the cold weather shutter as temps when I am cutting are rarely much below the threshold. Maybe using the cold weather shutter (on saws that have it, half of mine don't) reduces some of the need to retune for cold weather as the saw is breathing warmed air.

Tuning the carb is making an adjustment, it's not a tune up. So there is no maintenance schedule for it. You do it when needed. The owner's manual usually explains when you would do it.

There's no need to be afraid of carbs, they're pretty simple in concept even if theres' a lot of tiny parts in there. Saw carbs are more complex than say motorcycle carbs, because they have to run in any orientation.

This video explains how the fuel pump part of a saw carb works:
The H and L adjustments change the amount of fuel mixed per unit of air for low throttle and high throttle respectively. (on some carbs L also affects H some). Generally when tuning for an air temp change I only need to make a slight adjustment to the H screw. If you can remember the change you just made 15 seconds ago, it's easy to go back if it was the wrong way.

 

[rarefish383]

When it gets real cold here you might need to make some carb adjustments, a saw that ran great in september might not like minus 20 degrees F and mixed fuel leftover from the fall (probably got some water in it somehow, which is now ice...) but some minor fiddling and fresh mix back in business. Here they sell winter blend gas which has got some different ingredients in it. That and when the air is real cold it is more dense = more oxygen. So if you make no adjustments yr saw will run lean or just not run. I am not a huge fan of the computer carb on the ms 362c but when its cold cold and the way to stay warm is keep working, having to f around with a tiny screwdriver (dont drop it in the snow!) is not my idea of fun.

That being said, do you have winter in MD?

Not for years. might get 2 feet of snow and a week later it's 60 and mud. Might have seen zero 2-3 times in my life. Gets hot and humid in the summer. 100 degrees and 85% humidity is mere likely than Zero.

 

[Timber MacFallen]

Enthusiasts tend to be more interested in tuning and optimizing saws than busy tree services in general. It's like that with all sorts of tools and equipment across industries. Years ago when I worked as an auto technician people in the shop never spent any time maintaining their own tools and cars. After a long day they didn't want to deal with their own things. That's why mechanics often drive boring, simple frumpy cars.

There are definitely enthusiasts who are in tree work, but they are outnumbered by people who put in long days and go through saws every couple of years. This is why autotune and M-tronic make a lot of sense for professionals-just put gas in it and go. Yes, tweaking the carb for when it's 20 degrees out will help the saw perform better, but it's not essential.

Some good local saw shops will optimize the carbs at the time of purchase to work best with local conditions. Certain brands that come a little "lean" from the factory get richened up by a good shop so they don't get you coming back with a burned up saw.

Some manufacturers without modern computer carbs like Echo allow you to flip from Summer to Winter mode:

 

[pioneerguy600]

Ported saws get tuned every time used, sometimes several times a day. Depends on the operators experience with ported saws.

 

[Del_]

Whenever I am cutting I have a carb screwdriver handy and adjust if needed. It's not needed very often.

 

[KASH]

My dad always said if it"s running good leave it alone.You don"t have to change your carb adjustments very often A tweak once in awhile.
At our resort we had 20 hp Johnsons with fixed high and adjustable low speed needle.The low speed knob was on the outside of the hood but connected to the needle on the carb inside with a wire linkage.Humans have a built in desire to turn knobs every red blooded North American boy thinks he can make a machine run better.
I would dissconnect the wire linkage and leave the slow speed knob in place I would take the cover off the motor and set it to trollk perfectly and put the cover back on. When a customer rented the boat and motor when he returned it I would always ask how did the motor run.Nine times out of ten the guy would say super good I just had to adjust the slow speed to get it to troll well.
Kash

 

[Pioneer]

Some saws you need to tune almost every day, some saws rarely. I have a small screwdriver in the toolbox for the purpose, if I hear that a saws not right, it gets tweaked.
With large temperature swings it's pretty much a necessity on non auto tune carbs.

 

[president]

Some saws you need to tune almost every day, some saws rarely. I have a small screwdriver in the toolbox for the purpose, if I hear that a saws not right, it gets tweaked.
With large temperature swings it's pretty much a necessity on non auto tune carbs.

T1

 

[cranman1951]

My 266 xp I cut 125 cord a year with for 6 years and never adjusted the carb....just replaced bars and chains as needed, and in 2012 had to replace the plug. I work on a lot of saws now so I adjust carbs all the time...but when I was working them, never......BTW the 266 is stilll running like new, and pulls the handle out of my hand if not careful

 

[birddogtg]

A saw can change tune from a 35 degree morning to a 65 degree afternoon.