Treeaddict
Treehouser
Can the idle adjustment have an impact on starting? Also, is the best idle position just below the point where the chain doesn’t move or just above where the saw stalls?
Idle speed and starting
- Thread starter Treeaddict
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Burnham
Woods walker
Yes, and the first.
CurSedVoyce
California Hillbilly
Treeaddict
Treehouser
- Thread Starter Thread Starter
- #4
Thanks fellas! Just adjusted my climbing saw idle. Hopefully it’ll be 1 - 2 pull start again. I’ve read and watched many videos on tuning but only fooled with idle speed so far. A tach is going to be ordered in the near future so I can adjust high and low jets. I can’t hear pitch well enough to trust my ears and certainly don’t wanna damage anything
Nutball
TreeHouser
I think a lot of it depends on the particular saw and how it has been run, along with the weather conditions. The best practice is not only learn how to keep your saw's carb properly adjusted, but learn how best to start it. For a 2511T I find it starts best either with the choke set to full, then backed off by about 1/3, or just slightly squeeze the trigger when starting, if you have that precise of control in your fingers. I start almost all saws in a 2/3 choke position with fast idle engaged as it gets the most reliable start, and gets the fuel flowing faster if it is too cold or too hot. Understanding the sound of the engine when it was shut off can help too, because it may have experienced a very lean or rich condition which will help you know whether to give it more fuel, or more air when restarting. If my saw goes out of tune due to weather or something, or if it has a known restart problem, I will make restarting easier by how I choose to shut it off. A ms180 I use easily gets vapor lock in warm weather, so I may let it idle for a bit to cool off, then kill it with the choke, so it is primed for an easy restart.
I had someone complain that a 2511t I modified for them was hard to start, which they aren't the easiest in my opinion anyway. He seemed to have a method of using it opposite of what I anticipated and what I had used for testing. I tuned the carb to work best fully warmed up, and capable of making lots of big cuts without overheating while still quickly coming down to a steady idle. If it cooled down too much, it would not idle well.
I rarely use rpm for tuning, I go by idle stability, idle to full speed transition qualities, and whether it is 2 stroking or "4 stroking" at idle and full throttle.
I had someone complain that a 2511t I modified for them was hard to start, which they aren't the easiest in my opinion anyway. He seemed to have a method of using it opposite of what I anticipated and what I had used for testing. I tuned the carb to work best fully warmed up, and capable of making lots of big cuts without overheating while still quickly coming down to a steady idle. If it cooled down too much, it would not idle well.
I rarely use rpm for tuning, I go by idle stability, idle to full speed transition qualities, and whether it is 2 stroking or "4 stroking" at idle and full throttle.
davidwyby
Desert Beaver
This one is the quickest most to the point and best sound I know of. Wavering back and forth with the weight of the saw is good, and loaded and then lift, should 4stroke right away. Tune hot, they get leaner hot.
Magnus
TreeHouser
A strong steady idle before clutch engage is best IMHO.
As low as possible and still be strong and steady. Usually mean it is just under rpm were clutch engage.
As low as possible and still be strong and steady. Usually mean it is just under rpm were clutch engage.
davidwyby
Desert Beaver
Idle is tricky because the mix and idle speed screws both affect idle speed, quality, and responsiveness…there is a balance that can be hard to pin down. If a saw really doesn’t want to tune right, it may have a carb issue or air leak.
Ed L
Treehouser
Years ago, could NOT get my 026 to hold a "tune", problems were not consistant. Idle today, starting tomorrow, etc.
Took it in...Gene pulled the cover, played touch-e-feely with it...I'll order you a carb.
WTF?
Your throttle shaft bore is worn out, got play in it. No ****ing wonder it runs like crap.
Problem solved, lesson learned, something to check on a saw that sees heavy use.
Ed
Took it in...Gene pulled the cover, played touch-e-feely with it...I'll order you a carb.
WTF?
Your throttle shaft bore is worn out, got play in it. No ****ing wonder it runs like crap.
Problem solved, lesson learned, something to check on a saw that sees heavy use.
Ed
CurSedVoyce
California Hillbilly
I had a 200t do that to me and a couple FS250s. Leaned them out proper.
Magnus
TreeHouser
It is not a common problem with worn carb bodies. You see it sometimes on most carbs.
I thought it was a specific brand/model issue at first, but it isn't.
I thought it was a specific brand/model issue at first, but it isn't.
They also pool fuel at idle in the inlet boot, so after a while idling, they tend to load up, especially if you tip or move them, and spill the pooled fuel into the crank, but yeah, worn throttle shaft will do it too
.Ive had to bring back carbs to basic settings quite often after the owners have gotten creative with a problomatic saw.
Once the problem/ s are found and fixed you can proceed.
There is a process that stihl outline that gives you correct position of the LA or butterfly idle position on the saws.
This can be adopted to most other saws as well.
Depending on the size of the saw depends on the rpm its set to, smaller saws have higher idle etc, but for a 70cc type saw, ie a 460 here is the procedure.
LA is butterfly position.
L is the low mixture screw.
Warm up saw,
Set the LA to 3300 then lean out the L screw for max rpm, clockwise, if the max rpm is over 3700, bring back the LA to 3300 and start again. and ensure the max rpm is not over 3700.
Then set the LA to 3300rpm, then bring down idle speed to 2500 by using the L and richening it up turning anti clockwise.
Make sure its got good crisp acceleration off idle, and that it is happy idling and not loading up over 20-30 seconds and your good to go.
This ensures that the butterfly is set correctly, and your not chasing your tail adding LA then L and then LA etc
there is also a good vid online that shows this process too.
Yeah, a tach is a worthy investment when messing about with 2 strokes.
There are other ways to get close to this if you dont have a tach, ie most clutches engage at around 3600, so you can get close, but again, for what our pro saws cost, a tach is a small investment so we can make sure they are set right.
I also use the tach to get close to wide open throttle max rpm, but prefer to tune in the cut afterwards.
Magnus
TreeHouser
Setting up with tach can easily get a bit wrong. Not all saws in same model/version run as the spec's say and in some cases you set it less than it could perform.
Setting by performance is the way to go for me.
I set them to run right and perform as it is best. Difference in wood were it perform best can vary 3000 rpm often, sometimes 5000.
Take 5 saws of same model/version and test. I have done this many times.
Setting by performance is the way to go for me.
I set them to run right and perform as it is best. Difference in wood were it perform best can vary 3000 rpm often, sometimes 5000.
Take 5 saws of same model/version and test. I have done this many times.
davidwyby
Desert Beaver
Magnus
TreeHouser
It should run correct no matter position except starter down, some saws don't do that well.
Tipping front and it raise rpm usually indicate airleak in intake/cylinder if fuel line is right and correct.
Tipping front and it raise rpm usually indicate airleak in intake/cylinder if fuel line is right and correct.
moving it back handle down, bar up, wont make the fuel dribble back towards the carb or go lean, moving the saw about will dislodge the pooled fuel, the air flow will move it, and cause the saw to stumble as it goes into a rich condition.
Fuel pools there when you let it idle for prolonged periods of time, or if its set a bit too rich, happens a bit quicker.
Seems to be an issue with the 026/ 260 saws due to the intake boots design.
yeah, tach is a good place to start, then fine tune by how it responds to throttle etc, but having a tach does help to bring it back to a more usable base to tune from, tho after you have done it many times, you get an ear for it too.
davidwyby
Desert Beaver
Yes, the tilt down is a “too rich” check
Just to confirm, your talking about your ms260 saw ?
as mentioned before, its any real movement that will spill out the pooled fuel in the intake boot that will cause it to go rich and stumble at idle after its been idling for a bit.
moving your saw about, and getting it to change its idle on other saws can indicate many other things, tear in impulse, intake boot, seal leaks, stiff fuel hose, and filter not picking up/ moving with the fuel etc.
davidwyby
Desert Beaver
Magnus
TreeHouser
You have fuel in liquid form after carburetor?
If it is on start up after sitting it is some times a leaky main inlet valve.
When you use a saw it is in all positions pretty fast before it reach operational temp and optimal time for setting.
Setting saws after performance when they are warm usually allow you to notice/get passed these things before setting. When it performs correct, with max power it is often set at its best. Not much more to wish for. When it is set this way it is often on the richer side than normal, but as it runs and perform correct, it actually use less fuel over a day's work with better performance.
Setting saws on bench without load works, but you may not get the most out of the saw.
If it is on start up after sitting it is some times a leaky main inlet valve.
When you use a saw it is in all positions pretty fast before it reach operational temp and optimal time for setting.
Setting saws after performance when they are warm usually allow you to notice/get passed these things before setting. When it performs correct, with max power it is often set at its best. Not much more to wish for. When it is set this way it is often on the richer side than normal, but as it runs and perform correct, it actually use less fuel over a day's work with better performance.
Setting saws on bench without load works, but you may not get the most out of the saw.
Treeaddict
Treehouser
- Thread Starter Thread Starter
- #23
So warm up the saw before adjusting carb to factory rpm’s ?
davidwyby
Desert Beaver
Definitely. Like actually do some cutting. They get leaner as they get hotter.
Treeaddict
Treehouser
- Thread Starter Thread Starter
- #25
Great to know! Just got a tach yesterday and will be tuning all my saws. All of them have been at factory settings since purchasing. Some are 1.5 yrs old. Curious to see how close they are to factory rpm’s. How often should they be tuned?
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