how to tune ?

[Cummins2016]

I have lurked here for awhile but never posted. I have always taken my power tools to a dealer to have them tuned because I don't know how. As I look around around my shop I see a blower, weedeater and pole saw that won't idle. Also, the fedex man just dropped off MMWS 372 OE at my door and I had to call the MasterMind to have him help me tune the saw to my elevation. I would like to learn how to tune my stuff without having to phone a friend. Could someone help me educate me on this L,H and idle screws, please?

 

[Cummins2016]

I tried to post a pic of the 372 but apparently that didn't work either so I might need to be educated on how to post pictures too.

 

[SOS Ridgerider]

This is honestly the best video I have seen of how to tune a saw.

 

[angelo c]

This is honestly the best video I have seen of how to tune a saw.
https://youtu.be/29FiGmDQkaM

Miss Mitch much

 

[Lightning Performance]

A well trained ear or a tachometer goes a long way. Watch more vids and listen as they lift or finish the cut.
Idol is just fiddlin to get what you like. Throttle response is usually best with a rich low jet but not too much.
If the chain moves at idol, turn in down or look for problems in the clutch and drum area or an air leak causing a lean condition.

All this is assuming your saw is in good working order and the carb works right.

 

[popopboat]

3 screw, throttle, L and H
throttle simply opens throttle valve, L screw adjust idle, H screw adjusts "run-mode"
simply said, both L and H when rotated to the left richen the mixture, and to the right leans it.

I found that the best way to do it is to try it, but not with expensive stuff heh.
I always do this : turn a throttle screw few turns in, L screw all the way in then 1 1/2 turn back (or even 2 or more depends on the throttle response), start it and it should run, then adjust throttle screw until it idles
For H part, i turn H screw all the way in, then richen it really good so it doesnt fall apart from RPMs, then in full throttle turn H screw to the right until it stops four-stroking and 1/4 turn back, so it four-strokes barely.
If throttle response is slow, richen (L to the left) mixture.

Badly explained but thats how it pretty much goes, tachos are not the best if you dont know the saw, its not the same, some saws may run too lean with lets say 11k rpm, some too rich, depents on the airflow and stuff.

 

[huskyboy]

The H is the easy adjustment when you learn a to know what to listen for on a unlimited saw. Blubber out of the wood and clean up in the cut. Limited coils are a pain in the ass... fatten up the saw till it blubbers in the cut, then lean it till it cleans up in cut. No leaner than that. Be careful tuning too fat on the L, it can tend to hide a lean H adjustment from the extra fuel if the saw idles in between cuts. Then when you go to do a long cut the saw is too lean on the H. Restarts should be one pull when saw is hot. If it takes more than one pull your too lean on the L, open it a touch. I set L by turning it in leaner till idle starts to increase, then back off a hair. That gets you close, fine tune from there. Idle is easy to set... turn in idle screw till chain creeps then back it off a touch. This is all what I do if I don’t have a tach handy.

 

[Cummins2016]

Thanks guys, I have ordered a DTI TACH. I've watched some videos using the tach to tune the H with the throttle pinned. Can you use the tach to tune the L too or only the high?

 

[huskyboy]

Thanks guys, I have ordered a DTI TACH. I've watched some videos using the tach to tune the H with the throttle pinned. Can you use the tach to tune the L too or only the high?

Only the H and idle. L is tuned by listening to the saw, by how good the throttle response is and by how well it starts.

 

[Cummins2016]

w

The H is the easy adjustment when you learn a to know what to listen for on a unlimited saw. Blubber out of the wood and clean up in the cut. Limited coils are a pain in the ass... fatten up the saw till it blubbers in the cut, then lean it till it cleans up in cut. No leaner than that. Be careful tuning too fat on the L, it can tend to hide a lean H adjustment from the extra fuel if the saw idles in between cuts. Then when you go to do a long cut the saw is too lean on the H. Restarts should be one pull when saw is hot. If it takes more than one pull your too lean on the L, open it a touch. I set L by turning it in leaner till idle starts to increase, then back off a hair. That gets you close, fine tune from there. Idle is easy to set... turn in idle screw till chain creeps then back it off a touch. This is all what I do if I don’t have a tach handy.

When you say blubber, you mean the 4 stroking sound described in the video posted above? Thanks for the help

 

[drf256]

I use a tach to tune the L more often than the H.

My sequence, if you care to know:

Set carb needles 1 turn out for L and 1.5 - 2.0 for H. Turn the LA (idle) screw in a few turns.

Start saw on choke. If the idle speed is too low to idle when the choke/fast idle is off, turn LA screw in more. If the idle speed is too high, reduce by sound. Check rpm vs factory recommended setting. Make sure chain isn’t moving at factory idle spec. If it is, probably needs clutch springs. Adjust the L carb screw to highest Idle rpm, then fatten (turn out) just a bit. Check for best throttle response-usually need to fatten L a bit. Once there, adjust LA again to factory rpm. Low is DONE. Reference where the L screw wound up. If it’s more than 1.25 out, suspect an air leak.

Now for H, piss rev saw. See where your rpm is. Start to lean the H out by screwing the needle in. I usually bring a saw to around 12k, then put it in wood. If it’s not smooth sounding in the wood, lean out a little and try again. Keep doing it till you hear the right sounds, blubbering out of wood and smooth sounding in the cut.

For limited coils, tuning in wood is your only way. By sound until it goes from fat to clean sounding in the cut.

I’ve found out the hard way that the best way to know when a saw is broken in is to keep it on the fatter side and just listen. The saw will tell you when it’s ready for more. When they break in, they suddenly get fatter and fatter at the same rpm that they weren’t fat at before.

I will try to find an old 036 video of mine for you. I think it will let you hear what we are talking about.

 

[drf256]

 

[huskyboy]

w


When you say blubber, you mean the 4 stroking sound described in the video posted above? Thanks for the help

Yessir. This is the best video I’ve seen on tuning a saw.

As Doc said above if your clutch is bad... you will not be able to tune the saw like this.

 

[andyshine77]

[emoji106]

 

[Cummins2016]

Thanks guys,

Update, I have watched a ton of videos, the ones you guys have posted on tuning as well as many of just people making cookies to help train my ear to the gurgle. I put this new new knowledge to the use on an old Stihl blower this afternoon. I popped the limiter caps screwed everything in and then backed the L&H 1 and 1/4 and the idle 2. I had hell getting it to idle and rev like it was supposed too. Long story short, I pulled the screen out of the spark arrestor, which was clogged. Then, I went back to tuning and now it's running like a champ again.

Another couple of other questions that I have since my education on this has begin. In several of the tuning videos people talked about running new saws fat until they break in. How many tanks do you consider break in and do you lean your saws up after?

I understand my blower wasn't breathing. Conversely, I have a weedeater than is relatively new and ran fine last year. What would cause it not to idle this season. (It has never had ethanol mix)? I would think once the carb is tuned it would be okay for quite awhile. How often do you tune your carbs?

 

[Deets066]

Did you leave gas in the weed eater over tge winter?
Old gas, or oil deposits can cause irregular tune.

 

[huskyboy]

Thanks guys,

Update, I have watched a ton of videos, the ones you guys have posted on tuning as well as many of just people making cookies to help train my ear to the gurgle. I put this new new knowledge to the use on an old Stihl blower this afternoon. I popped the limiter caps screwed everything in and then backed the L&H 1 and 1/4 and the idle 2. I had hell getting it to idle and rev like it was supposed too. Long story short, I pulled the screen out of the spark arrestor, which was clogged. Then, I went back to tuning and now it's running like a champ again.

Another couple of other questions that I have since my education on this has begin. In several of the tuning videos people talked about running new saws fat until they break in. How many tanks do you consider break in and do you lean your saws up after?

I understand my blower wasn't breathing. Conversely, I have a weedeater than is relatively new and ran fine last year. What would cause it not to idle this season. (It has never had ethanol mix)? I would think once the carb is tuned it would be okay for quite awhile. How often do you tune your carbs?

Blowers and weedeaters are different than chainsaws as far as tuning goes. You lean the H out to where they juuust barely stop
4 stroking and no leaner. This is because they are already constantly “loaded” with either the blower fan or string trimmer head/string. Whether as saws are not loaded till you put them into the wood. You might need new carb gaskets in your string trimmer, but try tuning it and see what happens.

 

[Cummins2016]

Did you leave gas in the weed eater over tge winter?
Old gas, or oil deposits can cause irregular tune.

I drained at the end of the season but used it sometime in Jan. and that fuel has set in it until recently. I used canned gas in Jan.

 

[beaglebriar]

Thanks guys,

Update, I have watched a ton of videos, the ones you guys have posted on tuning as well as many of just people making cookies to help train my ear to the gurgle. I put this new new knowledge to the use on an old Stihl blower this afternoon. I popped the limiter caps screwed everything in and then backed the L&H 1 and 1/4 and the idle 2. I had hell getting it to idle and rev like it was supposed too. Long story short, I pulled the screen out of the spark arrestor, which was clogged. Then, I went back to tuning and now it's running like a champ again.

Another couple of other questions that I have since my education on this has begin. In several of the tuning videos people talked about running new saws fat until they break in. How many tanks do you consider break in and do you lean your saws up after?

I understand my blower wasn't breathing. Conversely, I have a weedeater than is relatively new and ran fine last year. What would cause it not to idle this season. (It has never had ethanol mix)? I would think once the carb is tuned it would be okay for quite awhile. How often do you tune your carbs?

Fresh gas and clean the air filter if you haven't already.