.. Adjusting Hi / Low screws

This is a tricky question, and hard to answer. Mainly, it depends on the weather in your area. Big temperature and humidity changes, yes, all the time. Fairly stable temps and humidity, no.
"Purists" looking to eek every bit of power out of the saw, every time they run it, period!
In a nutshell, it's up to you, I fiddle with them when the temp changes dramatically, or when the saw isn't running like I know it can.
Brian, being in Florida with a fairly stable temp and humidity, may never mess with them all year long. He doesn't have to. Here we go from 120 to -20 over a year, we have to.
If the fuel you use changes you have to as well. I use the highest octane fuel I can get, but even then it's not the same station to station. I have to adjust for that. Now we are looking at E20 fuel, I'll have to adjust again and lose power to compensate for the moisture.
Basically, if you are just a tree cutter, not interested in eeking every bit of power you can from the saw, run them a little rich and be happy. If you think you need every thing the saw can give, tune it every time you start it.
It's a fine line. I hope that helps at least a little.
 
Some saws seem to need more frequent adjustment, some none at all. You don't need a tach to adjust, but having a good one is cool. It's nice to reference a tach sometimes, it helps to teach your ear too. I dig adjusting, finding the sweet spot. I think it's a deep thing that borders on spiritual.
 
We used to have to adjust them for the conservation corps when I worked in Nevada. The saw shop was in Reno, 4500', Lake Tahoe was 6200-8500'. Death Valley was around sea level, or possibly below sea level, to 8000'. Different elevations have different amounts of air pressure, and available O2 levels. We used a tachometer. I never learned to do it by ear.

Now I stay at about the same elevation, essentially 0-300' above sea level, and have a small window of temps, usually 30-90 degrees F. I have a bunch of other things to focus on, and haven't messed with my saws adjustments really.
 
I stay at a constant elevation, and I've always felt they only need adjustment when they start to get old. Like when they need adjustment, it's the beginning of the end.
 
I can have about a 1, 2-3000 foot elevation variance to different job sites. I just carry the tach in the truck.
During the summer months, I will often check RPM on the brush cutters every couple of days or if there is a severe change in temp. They are the most susceptible to lean out of all my equipment.
 
Like your new motto, Stephen.

Is that a Daniel Murphy quote?
 
I stay at a constant elevation, and I've always felt they only need adjustment when they start to get old. Like when they need adjustment, it's the beginning of the end.

I'm in the same boat as Cory. No more than a hundred feet elevation change and temps are within a fairly tight range from 50-95 degrees. The saws can act up if I have to use one on a very cold day, but once they get warmed up they are fine. If an old saw starts running lean and begins to need more than a couple adjustments in a season then there's either an air leak or a bad carb.
 
After being here for 40 years I'm not really suited for adapting to sub freezing temps. We do get below freezing a few times per year here, but it is so rare that it is major news with the talking heads on tv all telling us how to survive. :roll:
 
Funny thing with adjusting the carb on the newly acquired 020, a Zama with no fuel pump. I couldn't get the high speed adjustment to bring the saw up to the max rpm specs, even with it closed all the way. :\: The low speed was too rich even though the idle and rev up was good. With the low speed closed more, the high speed adjustment worked as it should. Odd, that the low speed affected the high speed, usually it's pretty much only the reverse, has been my experience.
 
Somebody on the forum once posted how to tell if the low speed jet was too rich, and it has helped me a lot. Warm up the saw and then set it on the bench and let it idle for a full minute. Then quickly pick it up and flip it upside down without touching the throttle. If it stalls then the low speed jet is too rich, fuel is puddling in the bottom of the crankcase.
 
You are actually running on both jets . Once the pressure drop is greater across the high speed than the low speed the former takes over .

They will run faster than you might think if you have a plugged high speed jet and are just running on the low speed .

Fact is the last boot I blew on the 038 mag I'll bet it was running 10,000 with the butter fly completley closed off because it was sucking that much air . Because no air passed the high speed in that case it was all the low speed doing the work .
 
Somebody on the forum once posted how to tell if the low speed jet was too rich, and it has helped me a lot. Warm up the saw and then set it on the bench and let it idle for a full minute. Then quickly pick it up and flip it upside down without touching the throttle. If it stalls then the low speed jet is too rich, fuel is puddling in the bottom of the crankcase.

Awesome info and post Brian... Thanks..
 
Just repeating what I've read here.

As a climber it was always important to have a saw that could idle without dying and requiring a restart for every cut. I've always had trouble getting the low speed dialed in and it usually was because I had the low jet too rich (lean seize phobia). When I get one that I just can't get the idle right, I'll use this trick to see if it's too rich on the low end.
 
I had lots of practice setting carb screws on the old Jonsereds in the 1970s. Their carbs were bolted solid to the cylinders and every 8 hr day the vibs would turn the screws out a little. I had to carry a carb screwdriver in my work pants all the time.
Then in 1980 I bought my first 038 AV and its rubber boot intake maniflod solved that problem.
On most saws warm the saw up for a few minutes, then turn the hi, lo screws in seated but not too tight, back out 1 turn. Start saw rev up ,let idle set idle screw to right rpm [chain doesn't turn and doesn't die] squeeze throttle off idle if bogs turn lo out 1/8- 1/4 turn when accelerates good , hold WOT and adjust Hi till you get that sweet spot. Most saws I run the lo is 1 1/4, hi is 3/4 turn out.
There simple as that.
Willard.
 
The rpm on the 020 is quite stable when adjusting the high speed, compared to a lot of saws that when viewed with a tach, fluctuate a lot at the high end. It seems like a good quality. Like yours, Brian, mine seems right at home at about 14,200.
 
Skwerl, definetly a cool sounding trick. But if a saw will idle for a full minute on the bench, and without the chain moving at all, it probably has a good low setting, no? If after sitting a minute idling, you then floor the throttle and it revs without hesitation I would say it is good to go even without checking it upside down.
 
Jay, talking about the high end, what do ya'll think about how long it is acceptable to test run a saw at top rpm with no load? I may be wrong but I never like to hear it for more than 3 seconds, seems like it could blow.
 
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