Stihl MS194t Problems...

[singinwoodwackr]

I haven't done a check on the impulse line, however it might just be my high/low settings that are wrong. Started the saw again, with the idle screw all the way in. The "switch" on the handle was all the way down, in the start position. Started it as per the book and just let it run high RPMs. Ran fine. As soon as I pulled the throttle in, it died.

This is most likely just bad carb settings, correct?

Not necessarily.
If it won't run right with basic settings of 1 turn out, there is something else wrong. Idle screw should not be all the way in.

 

[lone wolf]

I haven't done a check on the impulse line, however it might just be my high/low settings that are wrong. Started the saw again, with the idle screw all the way in. The "switch" on the handle was all the way down, in the start position. Started it as per the book and just let it run high RPMs. Ran fine. As soon as I pulled the throttle in, it died.

This is most likely just bad carb settings, correct?

Pressure and vac test it and we can go from there.

 

[Bludenz]

Not necessarily.
If it won't run right with basic settings of 1 turn out, there is something else wrong. Idle screw should not be all the way in.

Idle screw is only all the way in because this is what ZeroJunk reccomended for testing. For me, it had to go all the way in until it kept running.

Pressure and vac test it and we can go from there.

Will do tomorrow hopefully. Will let you know the results.

 

[singinwoodwackr]

Idle screw is only all the way in because this is what ZeroJunk reccomended for testing. For me, it had to go all the way in until it kept running.


Will do tomorrow hopefully. Will let you know the results.

Test, yes but that ain't normal...somting wrong...

 

[ZeroJunk]

The one I am working on is doing more or less the same thing with two different OEM carbs.
It will slow down to an idle and then slowly die from that initial idle. That's just revving it up and trying to get the idle needle right. Really not sure where the idle speed screw is set.
But, when I stick it in my testing log it cuts off immediately when you let off the throttle.

Probably be Tuesday, but I'll let you know if I figure it out. May just be end of life low compression.

On yours, seems if it was an air leak you would be chasing it turning out your low needle since it is already getting air somewhere. Adding air by turning the idle speed screw all the way in doesn't indicate an air leak.

Check that little short impulse line. It could leak enough not to pump at idle, but have enough pulse revved up.

 

[lone wolf]

Air leak or maybe carb. Pressure and vac test, if good, it's the carb. Sounds like a big air leak to me!

 

[singinwoodwackr]

The one I am working on is doing more or less the same thing with two different OEM carbs.
It will slow down to an idle and then slowly die from that initial idle. That's just revving it up and trying to get the idle needle right. Really not sure where the idle speed screw is set.
But, when I stick it in my testing log it cuts off immediately when you let off the throttle.

Probably be Tuesday, but I'll let you know if I figure it out. May just be end of life low compression.

On yours, seems if it was an air leak you would be chasing it turning out your low needle since it is already getting air somewhere. Adding air by turning the idle speed screw all the way in doesn't indicate an air leak.

Check that little short impulse line. It could leak enough not to pump at idle, but have enough pulse revved up.

Check the low needle for damage...bent?

 

[singinwoodwackr]

Air leak or maybe carb. Pressure and vac test then replace carb if needed.

With 2 different carbs doing the same thing I would think it is something else

I have 2 192s to assemble next. Hope they don't follow this

 

[lone wolf]

With 2 different carbs doing the same thing I would think it is something else

I have 2 192s to assemble next. Hope they don't follow this

Pressure test is very helpful, it is the basis of all good builds.

 

[singinwoodwackr]

Pressure test is very helpful, it is the basis of all good builds.

as soon as the cylinder gets nailed down and sealant (if used) has time to cure, the p&v tools get attached, before the muffler and carb go on.

 

[ZeroJunk]

With 2 different carbs doing the same thing I would think it is something else

I have 2 192s to assemble next. Hope they don't follow this

I tried two different carbs. I think he is still on the original .

 

[stihltech]

"I think it is the adjustments" minus a vacuum/pressure test=scored piston and cylinder. Common issue in the shop.
Good luck.

 

[Bludenz]

Thanks for all of your responses.

I am still, on what is believed to be, the original carberator. It is a Zama C1Q-S138A. The part number does not match up from the Stihl MS192t IPL and manual. The manual/IPL says the Stihl ms192T carb should be Zama C1Q S103 or C1Q S104 (Japan). Could this be my problem? The carb fits and everything lines up - could be a 192/194 carb though - a quick google search did not help me out with this.

Piston and cylinder looked good through the exhaust port, might have to re-build again and get a new piston for it if it happens to be scored for whatever reason.

The one I am working on is doing more or less the same thing with two different OEM carbs.
It will slow down to an idle and then slowly die from that initial idle. That's just revving it up and trying to get the idle needle right. Really not sure where the idle speed screw is set.
But, when I stick it in my testing log it cuts off immediately when you let off the throttle.

Probably be Tuesday, but I'll let you know if I figure it out. May just be end of life low compression.

On yours, seems if it was an air leak you would be chasing it turning out your low needle since it is already getting air somewhere. Adding air by turning the idle speed screw all the way in doesn't indicate an air leak.

Check that little short impulse line. It could leak enough not to pump at idle, but have enough pulse revved up.

Thanks a lot for your response. Mine will stay in the high RPMs until the throttle lock is touched. The chainbrake does not work for whatever reason and the chain will spin regardless. If you touch the chain into wood it will basically instantly die, or go to very low RPMs. Somehow yesterday, I got it to "idle" after touching it into wood. Died very quickly afterwards though. The throttlelock was still held in. Touching the throttle after it has started (even pulling it in to "increase" the RPMs) will result in the saw instantly dieing.

Too late now, but I'll check the impulse line tomorrow, I have a spare to replace if needed. Might just replace if it isn't too hard.

Regardless, I will fiddle with the carb settings a little bit more before going further again. I will also try a pressure/vac test when I get the chance.

 

[ZeroJunk]

Thanks for all of your responses.

I am still, on what is believed to be, the original carberator. It is a Zama C1Q-S138A. The part number does not match up from the Stihl MS192t IPL and manual. The manual/IPL says the Stihl ms192T carb should be Zama C1Q S103 or C1Q S104 (Japan). Could this be my problem? The carb fits and everything lines up - could be a 192/194 carb though - a quick google search did not help me out with this.

Piston and cylinder looked good through the exhaust port, might have to re-build again and get a new piston for it if it happens to be scored for whatever reason.


Thanks a lot for your response. Mine will stay in the high RPMs until the throttle lock is touched. The chainbrake does not work for whatever reason and the chain will spin regardless. If you touch the chain into wood it will basically instantly die, or go to very low RPMs. Somehow yesterday, I got it to "idle" after touching it into wood. Died very quickly afterwards though. The throttlelock was still held in. Touching the throttle after it has started (even pulling it in to "increase" the RPMs) will result in the saw instantly dieing.

Too late now, but I'll check the impulse line tomorrow, I have a spare to replace if needed. Might just replace if it isn't too hard.

Regardless, I will fiddle with the carb settings a little bit more before going further again. I will also try a pressure/vac test when I get the chance.

Try taking the bar and chain off and see if it will idle... If it does figure out what is wrong with the clutch and drum.

If it is trying to turn the chain even at idle that could be enough load to make it not want to idle.

 

[Bludenz]

Okay... Took the bar and chain off, started it and fiddled with the carby to get it to idle... Reset it to factory settings as per the markings on the little plastic cover for the screws... and it idles and runs fine. Turns out I might've not set the carby settings right the first time...

However, from idle --> high rpms there are a few problems. If it is idling, and I hold in the throttle as much as I can for it to revv up, it bogs down and dies instantly. However, if it is idling and I blip the throttle in small increments, it will revv up and go to high RPMs fine. This, again, might be my lack of carby tuning skills starting to show. Put the bar and chain on and it exhibits the same behaviour. Cuts through 2x4 pine fine. If I let off the throttle it goes to idle fine.

Is it my carby settings that it causing the saw to bog down when I pull the throttle in all the way, or is there something else that could be the culprit?

 

[Bludenz]

Final post. To sum it up:
At first the saw started, high idle, and then died. Turned out to be cracked engine pan.
Got a second hand pan, installed it, reassembled, ran fine - didn't idle.
Turns out my carby tuning skills are not top notch.
Retuned carby, runs fine, idles fine, revs up fine now.

Turns out the brake band snapped for the chain brake, that's why it wasn't working. Will replace that and then the saw will be back to work.

Thanks all for your help!

 

[ZeroJunk]

Final post. To sum it up:
At first the saw started, high idle, and then died. Turned out to be cracked engine pan.
Got a second hand pan, installed it, reassembled, ran fine - didn't idle.
Turns out my carby tuning skills are not top notch.
Retuned carby, runs fine, idles fine, revs up fine now.

Turns out the brake band snapped for the chain brake, that's why it wasn't working. Will replace that and then the saw will be back to work.

Thanks all for your help!

Apologize for taking so long to get back about the one I was working on.
Turned out to have enough piston scoring/low compression not to idle, but would run when throttled up.
A new cylinder kit is surprisingly cheap for Stihl. See what he wants to do.