MS200T help me please

[TrueARbor]

Hello,

I am having a problem with my MS200T.

Problem: When I start the saw, the only way I can keep it running is by keeping it at full throttle. When it is at full throttle it pulses (the tip of the bar jumps up when I hold it level).

Also if I attempt to put it into a cut the chain slows way down and it will not cut much.

When it runs full throttle it sounds like it is under a load, sometimes the chain even stops spinning.

Sometimes when I start the saw I can hear it for just a second sound normal then it falls back down into a deeper sound and pulsates again.

What I have done:

Checked the fuel filter in the tank, fuel line, I removed the carb and removed the bottom (with single screw) and cleaned the filter with carb cleaner.

I removed the muffler cleaned the spark arrest. I ran the saw without the spark arrest, black junk in the muffler spat out of the muffler, at that point i opened the muffler and let it soak in fuel and used a wire brush to clean it.

Any ideas would be awesome, gotta get back to work.

 

[TonyRumore]

Chances are the accelerator pump circuit is leaking in the carb. You can put a "pump piston kit" in it that consists of an o-ring, piston, strainer, and spring and it will probably fix the problem (P/N 1129 120 9702). But in my experience, it is a short term fix and the problem will reappear. The permanent fix is to tap the accelerator piston bore with a 1/4-28 tap and loctite in a set screw to seal it up. Some guys use glue instead of a set screw, but that's a bit gay if you ask me.

Tony

 

[NPKenny]

Some guys use glue instead of a set screw, but that's a bit gay if you ask me.

How do you feel about epoxy with the original accelerator piston?? What is the benefit of the threaded insert? I can see zero advantage to tapping and threading a screw and I certainly don't plan on removing it..

BTW, this fix is really a necessary step on this saw and, presuming the rest of your saw is functioning properly, will likely make your saw run better than new.

 

[parrisw]

I use JB weld on the pump piston, take the oring off and JB weld in the pump piston, works great and is not GAY. I have one still running over a year now in a commercial environment. Oh, take out the spring behind the piston first. I also take out the tiny welch plug that covers the pump circuit and JB weld that shut too.

 

[tree monkey]

the acc pump only affects the saw at an idle
this is not the op's problem
sounds more like it's out of time
pull the flywheel and check the key
is the piston scored?
is your fuel fresh?
is it flooding?

 

[Naked Arborist]

You guys are just throwing stuff out there. He said the chain stops? Was it stopping free spinning or in the cut? Did he run it with out the bar and chain yet? Could be a seizing bar nose roller, just sayin. The chain brake could be hanging up.
If that's not it I'd have to go check the lower intake boot under the top cover plate before tearing into the saw again. If the saw runs like crap when you pull up on the handle we all know what that is, maybe he doesn't.
Diagnosing stuff site un-seen or un-heard is almost ridiculous.
More information is needed IMHO.

 

[NPKenny]

the acc pump only affects the saw at an idle

I agree with this in the most basic sense. In my experience however, I was always chasing a proper idle and off-idle throttle response through carb adjustments that I was getting a few of the OP's symptoms by never being able to predictably tune it.

 

[tree monkey]

You guys are just throwing stuff out there. He said the chain stops? Was it stopping free spinning or in the cut? Did he run it with out the bar and chain yet? Could be a seizing bar nose roller, just sayin. The chain brake could be hanging up.
If that's not it I'd have to go check the lower intake boot under the top cover plate before tearing into the saw again. If the saw runs like crap when you pull up on the handle we all know what that is, maybe he doesn't.
Diagnosing stuff site un-seen or un-heard is almost ridiculous.
More information is needed IMHO.

your right about the bar and chain

 

[tree monkey]

I agree with this in the most basic sense. In my experience however, I was always chasing a proper idle and off-idle throttle response through carb adjustments that I was getting a few of the OP's symptoms by never being able to predictably tune it.

yea your right
it sounds to me that the saw is laboring at full throttle

 

[TrueARbor]

I have not had time to pull the flywheel and check the key.

The fuel is new, mixed at 50:1

the muffler becomes wet after running

The bar and chain are in good condition, chain will move freely with the chain brake off.

idle is set to factory (LA , H , L )

It will not idle, to start it I need to keep the throttle open

with the carb off, if I attempt to run the saw, it will start and run for just a second if I spray some carb cleaner inside, it is much louder however it does not sound like it is laboring.

I am almost positive there is a problem with the carb

 

[tree monkey]

did you put in a carb kit?
sounds like the inlet needle is leaking

 

[TrueARbor]

did you put in a carb kit?
sounds like the inlet needle is leaking

there is no carb kit in it.

 

[tree monkey]

i think thats where i woud start

 

[tree monkey]

you said you took 1 side of the carb off(with 1 screw)
take the other side off and see if the welch plug came loose

 

[TrueARbor]

it looks clean on the other side (with 4 screws)

welch plug comes to a point and is attached to the rocker with spring

there was some white plastic material attached to the gasket, it must be some locktight or some kind of glue used to hold on the gasket.

could this little bit of material have prevented the rocker from moving and caused this issue. I can't run the saw until later to respect people that are sleeping.

 

[kr5258]

I had a similar problem on 2 of these saws. The welch plug had completely fallen out on one of them, the other was loose and leaking. They would only run at full throttle for a short while then flood out.

Sealed the welch plugs with fingernail polish. Dipped the tip of a pick in the polish and run around the edge of the welch plug. Worked like a charm, saws have been fine now for about 2 years.

 

[TonyRumore]

the acc pump only affects the saw at an idle
this is not the op's problem
sounds more like it's out of time
pull the flywheel and check the key
is the piston scored?
is your fuel fresh?
is it flooding?

I am going to have to respectfully disagree with you here. When that accelerator pump circuit goes bad, the fuel mixture goes lean/rich at random, from idle to WOT. It causes the operator to chase the tune up and down, over and over, until they finally give up.

Sometimes you will get it tuned out, then after you run it for awhile, the thing goes lean at WOT. So you fatten it up and it runs good for awhile, then all of a sudden, it running rich again. That's why this problem drives guys nuts.

I will agree with you though, when the accelerator pump circuit is operating PROPERLY, it only effects idle/off-idle response.

Tony

 

[lone wolf]

Op, I think your impulse line may be off check the left side under the air filter box and take a look at it!

 

[Chris-PA]

Can someone tell me the model number of this carb with the accelerator pump?

 

[TonyRumore]

C1Q-S126
C1Q-S127
C1Q-S128
C1Q-S129
C1Q-61D
C1Q-61E
C1Q-108
C1Q-108A
C1Q-S96A
C1Q-S109
C1Q-S61

I believe there were other models installed on these saws, but those are the models shown in my IPL.

C1Q-S32 is the only carb showing in my IPL that does NOT have the accelerator pump parts in it. It appears that carb was used on some of the rear handle 200's, not the top handles.