MS200T Power Loss

[Moto Vita]

My ten year old MS200T starts, idles, accelerates and revs to 14,000 rpm, but bogs down in a heavy cut. I've been using the saw almost daily recently and it seemed to happen overnight. When I noticed it I cleaned the air filter and put on a fresh chain, that didn't help. I read here about problems with accelerator pumps, so I pulled the carb off and I don't have one, it's a Zama S61A. I went through the carb anyway and everything looked OK. I don't run ethanol diluted gas and have always used high quality synthetic oil. I removed the spark screen when I got the saw but I pulled the baffle out and ran it that way, it did get more responsive but still bogs down in a heavy cut.
No one but me has ever run this saw, it doesn't have a ton of hours on it but it does get used hard periodically. It's always impressed me until now, it will cut limbs fine but doesn't have the torque to cut 12" soft wood logs like it used to.
Does anyone have any specific advice for me before I tear into it?

 

[Stihlbillie]

Comp test

 

[Stihlbillie]

And i dont think your carb has a accelerator pump

 

[Moto Vita]

And i dont think your carb has a accelerator pump

Correct.

 

[Moto Vita]

Comp test

Yeah I have a compression gauge but it's at my other shop. What pressure should I be looking for?

 

[CR888]

130-160psi. Is you spark arrestor screen clean in the muffler?

 

[Moto Vita]

130-160psi. Is you spark arrestor screen clean in the muffler?

Thanks,I don't use a screen in the muffler.

 

[DND 9000]

And i dont think your carb has a accelerator pump

The C1Q-S61 carburetors have an accelerator pump.

 

[Chainsaw Jim]

Sounds like the carb needs rebuilt with a new kit.
It shouldn't rev properly if it has low compression or scored cylinder.

 

[lone wolf]

My ten year old MS200T starts, idles, accelerates and revs to 14,000 rpm, but bogs down in a heavy cut. I've been using the saw almost daily recently and it seemed to happen overnight. When I noticed it I cleaned the air filter and put on a fresh chain, that didn't help. I read here about problems with accelerator pumps, so I pulled the carb off and I don't have one, it's a Zama S61A. I went through the carb anyway and everything looked OK. I don't run ethanol diluted gas and have always used high quality synthetic oil. I removed the spark screen when I got the saw but I pulled the baffle out and ran it that way, it did get more responsive but still bogs down in a heavy cut.
No one but me has ever run this saw, it doesn't have a ton of hours on it but it does get used hard periodically. It's always impressed me until now, it will cut limbs fine but doesn't have the torque to cut 12" soft wood logs like it used to.
Does anyone have any specific advice for me before I tear into it?

Need to check the compression first. It could be low compression. Carbs do cause lots of trouble on those especially if its ten years old. Maybe try deleting the accelerator pump. You tried fresh gas right? BTW The carb without the pump is a C1Q S32. You can buy an aftermarket carb from Definitive Dave it would not have the accelerator pump and a third of the cost of OEM.

 

[blsnelling]

Sounds like low compression to me.

 

[Moto Vita]

The carb is marked S61A, I swear it has no provision for an accelerator pump, I'll order a kit for it. I've been using the saw daily so fuel is fresh. I'll check compression too.

 

[CR888]

When the accelerator pump fails they behave in a distinct manner, my guess is its not accelerator pump related.

 

[lone wolf]

The carb is marked S61A, I swear it has no provision for an accelerator pump, I'll order a kit for it. I've been using the saw daily so fuel is fresh. I'll check compression too.

No need to order that yet. We can tell if it has the pump. Does it have the plate on it like this one that the arrow is pointing to?

 

[lone wolf]

My ten year old MS200T starts, idles, accelerates and revs to 14,000 rpm, but bogs down in a heavy cut. I've been using the saw almost daily recently and it seemed to happen overnight. When I noticed it I cleaned the air filter and put on a fresh chain, that didn't help. I read here about problems with accelerator pumps, so I pulled the carb off and I don't have one, it's a Zama S61A. I went through the carb anyway and everything looked OK. I don't run ethanol diluted gas and have always used high quality synthetic oil. I removed the spark screen when I got the saw but I pulled the baffle out and ran it that way, it did get more responsive but still bogs down in a heavy cut.
No one but me has ever run this saw, it doesn't have a ton of hours on it but it does get used hard periodically. It's always impressed me until now, it will cut limbs fine but doesn't have the torque to cut 12" soft wood logs like it used to.
Does anyone have any specific advice for me before I tear into it?

Does it do this on the first cut or does it take a minute to happen?

 

[J.W Younger]

Does it do this on the first cut or does it take a minute to happen?

Do think it could be the nose sprocket?

 

[lone wolf]

Do think it could be the nose sprocket?

Not too likely. I was wondering if it did it warm or cold , I would like to see if we can eliminate the coil as the problem. On those saws its usually a bad carb , vac leak , then bad compression and in that order. Still waiting for the compression numbers to get posted.

 

[lone wolf]

Sounds like low compression to me.

Could be , he said it happened over night, this would indicate a scored piston and rings possibly. Problem is until you tear it down you aint going to see everything.

 

[J.W Younger]

Not too likely. I was wondering if it did it warm or cold , I would like to see if we can eliminate the coil as the problem. On those saws its usually a bad carb , vac leak , then bad compression and in that order. Still waiting for the compression numbers to get posted.

My memory is bad but seems like I had one acting similar with a bad bar.

 

[lone wolf]

I compression test first , swap carb with a runner then tear down if needed and usually find the problem to be vac leak or scored piston at that point.