Ok, I've been defeated...

[Jason280]

A few of you have been following my Stihl 066 Magnum thread...

http://www.arboristsite.com/community/threads/stihl-066-magnum.263527/

Well, I spent the better part of the morning attempting to get the carb tuned, and I have failed miserably. I went ahead and completely disassembled the carb, cleaned/sprayed everything out, checked seals & gaskets, and reassembled. I started with my L at 1/4 turn out, and the H at 3/4, and was able to get good throttle response...but I simply cannot get the saw to idle. I seems to run great, but there is not enough forward adjustment on the idle screw to make any difference to keep it from cutting off. I went through the routine of turning the L jet out/CCW, which enabled me to get a decent idle set. However, throttle response is sluggish, it will still give me an occasional increase in RPM's (past 4k RPMs) regardless of throttle position, and will maintain 4-5k RPMs when the throttle is released after wide-open.

I'm not sure where to go from here. I have adjusted the L jet about as much as I can, and leaning out the mixture back to 1/4 turn seems to be the solution, except I cannot get the saw to idle and stay running. I even went ahead and did a compression test, just to make sure, and I am pulling 150psi on a cold saw. I've watched several YouTube videos, and something is just not clicking.

Maybe there is another culprit at play, I am not sure. Any suggestions?

 

[Rockjock]

A few of you have been following my Stihl 066 Magnum thread...

http://www.arboristsite.com/community/threads/stihl-066-magnum.263527/

Well, I spent the better part of the morning attempting to get the carb tuned, and I have failed miserably. I went ahead and completely disassembled the carb, cleaned/sprayed everything out, checked seals & gaskets, and reassembled. I started with my L at 1/4 turn out, and the H at 3/4, and was able to get good throttle response...but I simply cannot get the saw to idle. I seems to run great, but there is not enough forward adjustment on the idle screw to make any difference to keep it from cutting off. I went through the routine of turning the L jet out/CCW, which enabled me to get a decent idle set. However, throttle response is sluggish, it will still give me an occasional increase in RPM's (past 4k RPMs) regardless of throttle position, and will maintain 4-5k RPMs when the throttle is released after wide-open.

I'm not sure where to go from here. I have adjusted the L jet about as much as I can, and leaning out the mixture back to 1/4 turn seems to be the solution, except I cannot get the saw to idle and stay running. I even went ahead and did a compression test, just to make sure, and I am pulling 150psi on a cold saw. I've watched several YouTube videos, and something is just not clicking.

Maybe there is another culprit at play, I am not sure. Any suggestions?

I recently had a 026 that was doing exactly what you are talking about. It turned out that the LA screw was not making contact with the butterfly leaver. I tweaked that and it runs good now. I would turn the LA pretty much all the way in and nothing would happen.. so I had a closer look and found for some reason it was out of position. carefully moved it and it made proper contact. Good luck!

 

[broman78]

If it defeats you put it down then come back to it. If it defeats you a 2nd time break out the wallet.

 

[kyle1!]

Surely there is an AS member in your living vicinity that could lend a helping hand so don't throw in the towel just yet. Usually it is something simple that is overlooked but it drives you to commit acts of violence.

 

[old guy]

I have an ms360 that the throttle screw just touches the lever when it bottems out, but in this case I can tune it well enough to work, I've thought about shortening the screw.

John

 

[Jason280]

I checked the position of the idle screw in relation to the throttle arm, and it's making positive contact. Of course, whether it's enough contact is another matter. I'm sure it's just a matter of properly tweaking the L jet, but it has eluded me thus far.

Just to confirm, is there any reason to adjust the H jet at this point? I've left it at the factory preset of 3/4 turn, and haven't touched it...

 

[fearofpavement]

Did you have the screws out and clean those passages?
and based on the number of screw turns, I assume you have the limiters installed?
If the limiters are not installed, then your screw turns are way off for base settings.

 

[fearofpavement]

I checked the position of the idle screw in relation to the throttle arm, and it's making positive contact. Of course, whether it's enough contact is another matter. I'm sure it's just a matter of properly tweaking the L jet, but it has eluded me thus far.

Just to confirm, is there any reason to adjust the H jet at this point? I've left it at the factory preset of 3/4 turn, and haven't touched it...

Yes, it needs to be adjusted.

 

[fearofpavement]

There are a number of AS members in Georgia, tell us again where in the state you live and maybe someone can help you out.

 

[Jason280]

Did you have the screws out and clean those passages?

Yes, I pulled both jets and cleaned the passages.

and based on the number of screw turns, I assume you have the limiters installed?
If the limiters are not installed, then your screw turns are way off for base settings

No, I've removed the limit caps from both jets. I'm basing (and maybe incorrectly) the turns off the pictogram on the side cover of the saw. The "L" is marked 1/4, and the "H" is marked 3/4. I'm assuming this is 1/4 & 3/4 turns out from a solid stop, meaning, the jets turned clockwise all the way in, and then turned out 3/4 for the H jet and 1/4 for the L jet.

Yes, it needs to be adjusted.

I guess what I should have asked, could it being out of adjustment have something to do with my current issues?

Oh yeah, I'm located right outside of Milledgeville, about 45 mins NE of Macon.

 

[wisecobandit]

The settings ive got for the 066 mag are 1 turn out on each if that helps.
Assume you have set the needle height correctly as that would affect it.

 

[Jason280]

Assume you have set the needle height correctly as that would affect it.

Not sure I understand...

 

[fossil]

That would be the lever height of the metering needle inside the carb.

 

[zogger]

A few of you have been following my Stihl 066 Magnum thread...

http://www.arboristsite.com/community/threads/stihl-066-magnum.263527/

Well, I spent the better part of the morning attempting to get the carb tuned, and I have failed miserably. I went ahead and completely disassembled the carb, cleaned/sprayed everything out, checked seals & gaskets, and reassembled. I started with my L at 1/4 turn out, and the H at 3/4, and was able to get good throttle response...but I simply cannot get the saw to idle. I seems to run great, but there is not enough forward adjustment on the idle screw to make any difference to keep it from cutting off. I went through the routine of turning the L jet out/CCW, which enabled me to get a decent idle set. However, throttle response is sluggish, it will still give me an occasional increase in RPM's (past 4k RPMs) regardless of throttle position, and will maintain 4-5k RPMs when the throttle is released after wide-open.

I'm not sure where to go from here. I have adjusted the L jet about as much as I can, and leaning out the mixture back to 1/4 turn seems to be the solution, except I cannot get the saw to idle and stay running. I even went ahead and did a compression test, just to make sure, and I am pulling 150psi on a cold saw. I've watched several YouTube videos, and something is just not clicking.

Maybe there is another culprit at play, I am not sure. Any suggestions?

Throttle linkage? Either a wrong cable or a bent rod, I don't know what ya got. My 394 was giving me fits like that, turned out I had to trim about 1/8th off the throttle cable casing so it would fit the trigger assembly dealie better, and give full throttle play.

It's still hard to start for me, but at least once running it will run and spool up nice and idle.

 

[zogger]

If you remember what exact carb you have, you can go to that carb company website and see pics of how to check or adjust metering level height. It's not hard to do, but makes a BIG difference in how the carb works.

 

[Big_Wood]

the metering lever on the metering side of the carb is most likely set to high like wisecobandit said. 1/4 turn of the low is not enough. your getting the best response there because closing the jet is holding off alot of the diaphragms pressure which is what pumps the fuel through the jets to the nozzle. set it properly with jets opened a turn each and it should be good to go.

 

[Jason280]

I think I figured out what you mean by the metering lever. If I understand this correctly, its simply the opposite end of the lever holding the needle in the inlet. I've found a few links, and looks like 0.065" below the surface/edge should be a good depth. It reminds me of having to adjust the float on a small engine carb. Guess I need to dig out some feeler gauges and pull the carb again!

eta: just found a pic of the Walbro "W" tool, doesn't look like it would be difficult to fab one up in the shop.

 

[hseII]

I haven't read your other thread;

Have you checked/ changed your impulse line?
I had a MS460 do the exact same thing to me, and yep, it was an impulse line that worked until the saw warmed up.

YMMV

 

[Bilge Rat LT 20]

On any used saw that is not running right, unstable RPM etc. you should replace fuel line, impulse hose, and the intake boot. Rubber parts die over time and cause trouble.

Also get the numbers off the carb and get a carb rebuild kit. Get the metering lever tool too, they are cheap and most suppliers that have the carb kits have them.

Rebuild the carb then you will have the fuel system in good shape to run the saw for a while.
Air leaks from bad rubber parts kill saws.

In your other post the RPM problems point to carb and rubber line issues.

This is an older saw that has been run not by you, no telling how the PO treated it.

 

[Beer Gut]

Yes, I pulled both jets and cleaned the passages.



No, I've removed the limit caps from both jets. I'm basing (and maybe incorrectly) the turns off the pictogram on the side cover of the saw. The "L" is marked 1/4, and the "H" is marked 3/4. I'm assuming this is 1/4 & 3/4 turns out from a solid stop, meaning, the jets turned clockwise all the way in, and then turned out 3/4 for the H jet and 1/4 for the L jet.



I guess what I should have asked, could it being out of adjustment have something to do with my current issues?

Oh yeah, I'm located right outside of Milledgeville, about 45 mins NE of Macon.

I think we all missed it here. You're saying you removed the red limit caps? Then it's one full turn out CCW from fully seated on the H and L.

Unless I miss read something.