Ms200t bogging

[scheffa]

Hey all, looking for some help.
Just put a new piston in a 200t that was burnt up at work, put it all back together started fine.
It has a big big when accelerating?
Runs good if you feather the throttle.

I found this part in the box of bits and can't find a home for it and not even sure it belongs to this saw, any help would be awesome.
Pn 11281217000Wo

 

[Chainsaw Jim]

The spare part is a plate that stabilizes the throttle linkage for the ms440/460.

It will be necessary to diagnose the problem that caused the failure or it will likely be doomed to fail again very soon.
You may have a bad carb on the 200t if it is an early one. Did you rebuild the carb with a new kit? They tend to go through fuel filters. also check the tank vent.

 

[scheffa]

Nah didn't rebuild the carb, piston looks as though it had bad fuel, would a fuel filter or vent cause the big off idle? I would have thought that impact wot more so

 

[scheffa]

 

[rd35]

Based on your description it is running lean.....which is likely the reason why it "burned up" in the first place. Like Jim alluded to...I would be looking at the fuel filter, fuel line, thank vent, and carburetor to figuring out why it is starving for fuel.

 

[rd35]

Oh, you posted the pics while I was replying. WOW that piston top took a beating. Looks like a spark plug tang broke off and bounced around in there. Nasty! Is your cylinder okay?

 

[Whiskers]

Did you check the spark arrestor in the muffler. They get clogged on the 200t and make them run like crap. You can also do some research on the carb issues on these.

 

[lone wolf]

Sounds like the vac line is off at the handle- airbox end or the carb is sucking vacuum. Check to see if the vac line is connected then we can check the carb next.

 

[SEAM]

Possibly a worn accelerator pump (piston) in the carburetor causing sluggish performance (running lean!!)... The 020T carb was better.

 

[scheffa]

The impulse line is connected and all looks pretty good.
Weird thing is we have two 200ts that the same thing happened to.
Cylinder is ok. Some pitting in the head but otherwise ok

 

[Poleman]

Looks like something went through the saw. Is the catch for the air clearer cover still there? I've seen those come loose and trash a saw.

Also it does sound like it is lean off idle, try richening the L screw to see if that helps. If not you'll have to look deeper. A carb rebuild may be in order. How did the saw run before all this?

 

[scheffa]

So I have checked the impulse line, filter and tank vent, ran the saw with the filter off and fuel cap off and still sluggish of idle, with the saws a fee hundred revs above idle the throttle response is great.
Remove the carb which is a zama 126, will block off the accel pump tomorrow after getting some Jb weld or similar

 

[SEAM]

I did an MS200 today - same symptoms, but SURPRISE , no accelerator pump...

Cleaned the jets and needles, and the saw runs like new. Now I got to tackle the flippy fuel cap which is leaking - I hate those...

 

[Whiskers]

Did you check the spark arrestor or not?

 

[Echoboy86]

That damage is caused buy the helical air filter twist lock tab(s) breaking off and going throughte saw. I've had 5 like it this year. Exactly the same damage, piston top an squish band peened to hell but, cylinder plating is pristine. Your current erratic running is more than likley a worn accelerator pump piston or o-ring. JB weld should fix it. Savage Saws.

 

[lone wolf]

The impulse line is connected and all looks pretty good.
Weird thing is we have two 200ts that the same thing happened to.
Cylinder is ok. Some pitting in the head but otherwise ok

I need to see a pic of the carb with it mounted on the saw to see if it has an accelerator pump, then we can try to fix that.

 

[spudulike]

That damage is caused buy the helical air filter twist lock tab(s) breaking off and going throughte saw. I've had 5 like it this year. Exactly the same damage, piston top an squish band peened to hell but, cylinder plating is pristine. Your current erratic running is more than likley a worn accelerator pump piston or o-ring. JB weld should fix it. Savage Saws.

This fella is bang on with this diagnosis, also seen this issue a few times, usually when the filter cover screw has been forced.

The bogging - could just be the L screw a little lean but other than this, the accelerator pumps are always an issue on these saws. The welch plug on the back of the saw can leak and will seep fuel if it is connected to the fuel line and the throttle opened and closed a few times. The welch plug covering the low speed jets can leak on older carbs, the red seal used on later carbs is usually damn good but the earlier ones often leak.

 

[Chainsaw Jim]

Jb welding the carb or disabling the accelerator pump as a troubleshooting tactic is a very very bad idea. Especially if the carb doesn't have a new kit in it. New oem pistons for these saws are only about $25 or $30. The case needs pulled apart to clean or replace the bearings and seals as aluminum dust has likely contaminated them.

 

[lone wolf]

Jb welding the carb or disabling the accelerator pump as a troubleshooting tactic is a very very bad idea. Especially if the carb doesn't have a new kit in it. New oem pistons for these saws are only about $25 or $30. The case needs pulled apart to clean or replace the bearings and seals as aluminum dust has likely contaminated them.

I cant see how it would hurt to delete the accelerator pump? He can pick up a cheap carb from Definitive Dave and they actually work fine they have a high and low adjuster needle. The H is not restricted either.

And yes he should clean that case out.

 

[spudulike]

Disabling the accelerator pump will lose a little pickup speed when cranking the throttle open but it will return a steady idle to the saw without effecting WOT. I usually replace the pump and only disable as a last chance option.