Echo 590 Timberwolf "H" setting

[hatfield]

My neighbor is having some problems with his saw running properly. Trouble starting and then stalling. Told him to bring it over to see if I could help.
He had removed both limiter tabs and the deflector plate on the muffler and left the screen in. That's the only mods.
I removed what little fuel he had in the tank and added mine. I run 91 ethanol free all the time. I started adjusting the carb and started to run much better. Finally got it to idle and the throttle response was spot on. Adjusting the "H" in the cut revealed only 1-1/8 turns CCW from full CW. I found this to be strange. My Timberwolf "H" screw is out 3 full turns CCW with the same muffler mod.

Just wondering if anyone else has "H" 1-1/8 turns CCW on their Timberwolf with the muffler deflector plate removed.

Thanks

 

[hatfield]

As not to confuse. Just the metal facing the rear of the saw was removed on the muffler deflector. Not the entire deflector.

 

[Andyshine77]

This may help.

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[hatfield]

Thanks Andy. I know how to tune a chainsaw. I was just wondering if anyone else who owns a 590 has approximately the same "H" screw setting at 1-1/8 turns CCW after a MM.

 

[hatfield]

Just curious. How many turns CCW on yours ?

 

[bmwpowere36m3]

I think that's where mine is... same MM and about 6 tanks thru it. Sea-level and running it this past weekend in 70* weather. Certainly not 3.

 

[hatfield]

Thanks for the response. I checked mine again to make sure. It's out 3 turns.

 

[Andyshine77]

3 turns out on the H is way too much, try one turn out and go from there. To get the H right where you want it, tuning in the wood is your best bet.

 

[Andyshine77]

The carb on the 590 is a bit different than most saws, having the H 1/2 a turn out is not uncommon. In fact the saw will still run OK with the needle fully seated. If you're saw doesn't have any underlying problem, it will be running dog rich with the H turned out 3 full turns.

 

[NC Cutter]

The carb on the 590 is a bit different than most saws, having the H 1/2 a turn out is not uncommon. In fact the saw will still run OK with the needle fully seated. If you're saw doesn't have any underlying problem, it will be running dog rich with the H turned out 3 full turns.

Good thread! I'm all ears whenever people in the know talk tunning.

 

[mountainlake]

Mine is 3/4 turn out and still a little rich in warm weather. Steve

 

[hatfield]

I went back out and pulled my carb to check the caps. It seems the limiter cap on the "H" screw is not a tight fit. I pulled it out, then turned the screw CW without it. I'm at 1 full turn. It appears the limiter cap was only grabbing the screw head at a certain spot. Therefore, making it 3 turns CCW. I switched out the "L" cap. Much tighter fit on the "H" screw. Now it turns the "H" screw properly.

 

[Andyshine77]

Mine is 3/4 turn out and still a little rich in warm weather. Steve

I had mine down to 1/4 a turn out this summer in 98° heat, my MS211 was the same way.

 

[hatfield]

Thanks to all for responding.
Andy. I just won't cut wood or do much of anything outside when it gets that hot. Not good for my heart.

 

[Andyshine77]

Thanks to all for responding.
Andy. I just won't cut wood or do much of anything outside when it gets that hot. Not good for my heart.

Not too crazy about it myself.[emoji6]

 

[Red97]

I had mine down to 1/4 a turn out this summer in 98° heat, my MS211 was the same way.

I know how to fix that if you are interested...

To the op

These 590's like 3/4 to 1 turn out on the high

1- 1 1/2 on the low.

 

[Chris-PA]

I had mine down to 1/4 a turn out this summer in 98° heat

Does your saw have a muffler mod?

 

[Andyshine77]

Does your saw have a muffler mod?

Yes.

 

[Chris-PA]

Yes.

So that's the issue. Chainsaw carbs in general give a fuel mixture that varies wildly with changing air velocity (rpm at WOT), getting much richer with only a small increase in air velocity through the venturi. The carbs on the Echo 590 have a fixed H jet set up to supply most of the fuel with the H needle providing only a small trim to that fuel - a small adjustment range on what is basically a fixed H jet carb.

With an effective muffler mod increasing the air velocity through the carb (which is just like increasing the rpm that causes 4-stroking), the mixture is now richer and out of range of the small H adjustment.

These carbs are not accurate enough for what Echo is trying to do without even a cat. The basic inaccuracy of the carbs is really what AT was intended to address - creating an all position fuel system that can also hold a fixed mixture.

 

[Andyshine77]

The carb was a bypass that provides 80% of the required fuel even with the needle seated. This is how they run stock as well, the issue was the thin hot air IMHO. I haven also never experienced violist issues others have with stock carbs, even with 100% exhaust to port ratio.

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