Question on Saw tuning

[NYWoodsman]

What is the relationship between the idle adjust and low speed adjustment. Where should the idle adjustment be? Two turns in to open the throttle butterfly, or just one turn? It seems manufactures never give you a starting point? Being that the idle adjust and low jet both effect idle speed how do you know your chasing the right adjustment to raise and lower idle if you don't know where to set the idle screw from the get go. Any clarification will be appreciated. And I'm talking about saws that have had limiters on adjustment screws removed.....

 

[ErnieG]

Good video here ....https://youtu.be/83NF1q0UYPw

 

[Mad Professor]

Adjust your idle so your chain don't spin. Then adjust low rich (CW) until it dies /gets too rich, then adjust it lean until it races (CCW). Set it between those two points. Reset idle speed if needed. You may need to repeat this a few times.

See if saw revs if properly from idle. If it stumbles richen low. Adjust idle.

 

[Gypo Logger]

What is the relationship between the idle adjust and low speed adjustment. Where should the idle adjustment be? Two turns in to open the throttle butterfly, or just one turn? It seems manufactures never give you a starting point? Being that the idle adjust and low jet both effect idle speed how do you know your chasing the right adjustment to raise and lower idle if you don't know where to set the idle screw from the get go. Any clarification will be appreciated. And I'm talking about saws that have had limiters on adjustment screws removed.....

Here’s what I do when I set up a carb after a rebuild.
I get the saw running and I turn in the idle screw enough to get the chain turning, then turn in L to hear and see the highest rpm, then back off L about 5 minutes, then check for throttle response,
Then back off idle to where the chain is at rest.
Ok, to repeat to get it just right.
Lastly adjust H to highest revs and back off 5 minutes.

 

[Mad Professor]

Here’s what I do when I set up a carb after a rebuild.
I get the saw running and I turn in the idle screw enough to get the chain turning, then turn in L to hear and see the highest rpm, then back off L about 5 minutes, then check for throttle response,
Then back off idle to where the chain is at rest.
Ok, to repeat to get it just right.
Lastly adjust H to highest revs and back off 5 minutes.

???

 

[NYWoodsman]

Good video here ....https://youtu.be/83NF1q0UYPw

Good Video

 

[Gypo Logger]

???

Just envision the face of a clock.

 

[Mad Professor]

Just envision the face of a clock.

You shoot rifles at all? A minute can be minute of a degree. First thing I thought of.

You implied 1/12th of a turn/circle/revolution.

That might not do it on Hi to get back rich enough from max rpm. I go from rich out of cut to cleans up in the cut. Can fine tune leaner from there in small increments.

 

[ZeroJunk]

You have to adjust the idle screw in enough that the saw will stay running, even if the chain is turning. Then adjust the idle mixture to peak RPM. Richen from there counter clockwise maybe an 1/8 of a turn, or 1/16 would probably be closer to 5 minutes. Then back the idle adjust back until the chain stops turning. Re adjust as necessary until you get a smooth transition from idle to higher throttle.
Reason being when you open up the butterfly, particularly if you do it quickly, you have to have enough fuel coming out of the low jet that it doesn't stall.

Caveat to all this being that you don't have a bad clutch, broken or weak clutch springs so that the chain never stops unless you hit the chain brake if it has one. See this quite a bit on older or high hour saws. I can't stand a chain turning all the time and replace the springs if it does.

 

[2StrokeFondler]

What is the relationship between the idle adjust and low speed adjustment. Where should the idle adjustment be? Two turns in to open the throttle butterfly, or just one turn? It seems manufactures never give you a starting point? Being that the idle adjust and low jet both effect idle speed how do you know your chasing the right adjustment to raise and lower idle if you don't know where to set the idle screw from the get go. Any clarification will be appreciated. And I'm talking about saws that have had limiters on adjustment screws removed.....

If you look closely at the carb, there will be one or more tiny holes just behind the fully closed butterfly. When the saw idles, she gets all the fuel through these tiny holes, controlled with the L screw. My starting point for the idle screw is just open enough that I can see the first tiny hole. Plus a turn, or so. It doesn't really matter, as long as the saw starts and runs somehow. Gonna adjust the carb properly anyway.
Obiously, this doesn't work on saws where the idle screw is not part of the carb, but part of the case.