2 stihl saws with the same exact problem

[goatchin]

I have 036 pro and 046.

Rebuilt 036-new piston, no base gasket but used suitable liquid gasket to achieve squish new impulse and fuel line and filter, rebuilt carb, opened exaust up a 1/2" all way around from stock, and had shop tune it for me.

046 required new intake boot and fuel line. no base gasket but used suitable liquid gasket to achieve squish ,opened exaust up a 1/2" all way around from stock also tuned by shop.

I put those two phrases in italics because they are the only things that have been done the same to each saw.

Both start right up, normal cold start procedures. Warm up and cut for 5 min tops (about enough time to be fully warmed up and at operating temp i'd assume). After this the saws will idle real choppy and plum quit. takes two pulls to start back up.

-Both saws are running same fuel mix as my 372 that has no problems (50:1). stall after cutting same hardness of wood-no extra load other than based on engine size.

-I have tryed opening the gas cap after stall to hear for hiss...but always hear a hiss and fuel will spill out cap when opening.

Thinking maybe tank vents are plugged on both???? both saws do this.
-Being both are running without base gaskets but with temp and fuel proof gasket maker. I know many here are using this method to attain desire squish.

I'm out of ideas. I figured i'd ask here first before bought two tank vents and put both gasketst back in. Hope i gave enough info.

 

[gmcman]

What gasket material did you use specifically? Did you torque the headbolts to spec? Just curious to eliminate possibilities.

 

[Saw Dr.]

Your shop tuned the idle circuit too rich on both. Lean it out a little

 

[goatchin]

I'll have to run over to the shop quick to check on specific name. honestly no i didnt torgue to spec because i have gotten the right socket configuration together to be able to use the 3/4" torque wrench on the small bit head and be able to get through the fins.

I didnt mess with the H and L screws. I did though turn down the idle bc they were both set to have the chain turning when i got them back.

 

[goatchin]

Versa-chem Gasket sealant type 2-non hardening, pliable, leak proof.

reistant to motor oil, gas, diesel oil, fuel oil, kero, lube, antifreeze, water, steam, synth. oil, salt solution and mild acids.

temp range=-65f to 425f

pressure range=5100 psi

 

[leeha]

Not sure if i understand the porting at
1/2" all the way around.
If your porting is way off it will be like
putting the wrong cam in a four stroke motor.
And just plain won't run right no matter what
you try to do.


Lee

 

[pioneerguy600]

Hope it was a typo error but please don`t tell me you are contemplating using a 3/4" drive torque wrench on a chainsaw.
Pioneerguy600

 

[gmcman]

I'm gonna say you have the L needle too lean and the idle screw is too low. Leaning the L will cause the idle to raise slightly. I would open the L about 1/8 turn at a time and increase the idle speed via the idle adj screw.

I'm going back to my R/C engines that I have messed with for many years, I know this is not an R/C engine but what you describe is something I have adjusted for friends many, many times.

The fact it could be lean on the low end is why it's stalling out...not enough fuel.

I could be completely off on this and B200 could be right on the money...hard to tell without hearing it. But either way could cause your probs.

Just curious, does your torque wrench read below 10 foot pounds? Never seen a 3/4 drive used for low values like this....curious cuz I would like one

 

[goatchin]

Exuast exit out of muffler-opened it up to each side of the exaust defelctor. all on stock hole. others have done more when doing dual ports.

That was sort of dry humor meaning that I dont have a torgue wrench that small. The wrench itself is either 1/2 or 3/4 cant remember. I tightened the bolts down till they had a small creak when turned more, but no tighter.

nope she dont read below the 10 ftlbs....our farm equip requires a touch more than that....had some humor in there haha

 

[TRI955]

Your shop tuned the idle circuit too rich on both. Lean it out a little

:agree2:
Both sound too rich on the low side....

 

[gmcman]

Depends on your budget, but I have this one and it works great.

http://www.sears.com/shc/s/p_10153_12605_00944593000P?keyword=craftsman+torque+wrench

Or even the beam-style which is cheaper but works fine.

Seekonk or Precision instruments makes nice dial-type for a little more $$$.

I would definately torque the headbolts to spec.

 

[Saw Dr.]

:agree2:
Both sound too rich on the low side....

:agree2:

Mixture gets richer as the saw warms up. If they "adjusted" your saw, and it was not up to full operating temp, then they're too rich.

Make a note of where the "L" screw is, and turn it in 1/4 turn. Then see what happens.

Better to try the easy stuff first, and then worry about the rest.

 

[goatchin]

:agree2:
Both sound too rich on the low side....

I dont know how to tune my saws (would if a shop nearby wasnt so "prickish"). I'm going to assume i would want to turn the idle back up to where the chain is turning and back down the L screw until it stops.

I really dont want to have to make a trip up to Rome to GKS and have them help me bc that is a drive longer than i would like to make....Great people and service just too far for one thing

 

[Saw Dr.]

I dont know how to tune my saws (would if a shop nearby wasnt so "prickish"). I'm going to assume i would want to turn the idle back up to where the chain is turning and back down the L screw until it stops.

I really dont want to have to make a trip up to Rome to GKS and have them help me bc that is a drive longer than i would like to make....Great people and service just too far for one thing

The best way to learn is to just try tuning it yourself. Count the number of turns that it takes to screw the mixture screws in. Don't force them, just lightly seat them. Write these numbers down somewhere. You can always go back to these settings if you need to. I usually start a 1 1/4 turns out. If the screws are not between 3/4 and 2 turns, something is wrong. There are several threads on here and elsewhere on carb tuning.

 

[goatchin]

I'll give it a try...again...and see where i get to.


Thanks for the help everyone-would be nice if shops around me were as helpful and willing to actually to you about fixing your equipment and not just telling you to come back when they are done.

If any more ideas come up give me a shout-thanks again

 

[smilin possum]

These guys have hit it on the head. I agree it sounds like a tune problem. I always run um all the way in lightly and back out about 1 1/4 this will most of the time get um to start and you can fine tune from there.

 

[Brmorgan]

Another vote for the L jet being rich. Many dealers will just tune a saw to the factory specs instead of where it actually runs the best. My 181SE is ported and running w/o base gasket at 180 PSI, and for a long time after doing the mods it would often stall out after being allowed to idle down from a hard cut. It always started right back up though, so it didn't occur to me to lean out the low end for quite a while. Turned it in 1/8 turn and it's been much better.

You may have to pull the limiter caps off your carb to get it to tune to the best spot.

 

[046]

here ya go... tuning instructions
http://www.madsens1.com/saw carb tune.htm

go to Madsens menu for other good articles. you may also need to do a vacuum/pressure test. if you can't get carb dialed in.

I dont know how to tune my saws (would if a shop nearby wasnt so "prickish"). I'm going to assume i would want to turn the idle back up to where the chain is turning and back down the L screw until it stops.

I really dont want to have to make a trip up to Rome to GKS and have them help me bc that is a drive longer than i would like to make....Great people and service just too far for one thing

 

[timberwolf]

+1 046, also learn to tune mixture on a stock saw that is more predictable and easy to hear the change as opposed to something that has been tinkered with and is an unknown. Once you get it down on a stock saw it will be easy to go at a modified saw.

 

[goatchin]

have good news and some frustrating news.

Good news: 036 just took a little tweekin on the L jet and now it doesnt bother a bit.

Frustrating news: got the 046 tweeked in good at first (had full tank of gas). cuttin away with it and could NOT get it to stall-good. Let it sit for a bit then started cuttin again and it would take a long time to idle down when taken out of the kerf. Eventually it got to the point where it was leaning itself out so much it was almost as if i had it at half throttle, then would burble and quit. no problem startin back up.

I got the idea to open the gas cap when it was leanin out on its own and see if it would come back down (testing for plugged vent)...negetive-still raced.

The filter is covered with fuel still-1/4 tank so its still gettin fuel.

Myself, I am thinking that when the saw gets 'hot' (not too hot) an air leak develops some wheres?????? Am i on the right track?