Used ms250

[jesse916]

Hello, I just bought a used ms250 from a guy. Wasn't sure what they had done to it. Found 2cycle oil in the bar oil reservoir. But can't get it to start. I'm guessing it's the carb. Also not sure it's even the right carb. The serial # is 262891917 . Does anyone know the correct part for the carburetor? I appreciate any help I can get.

 

[epo]

Hello, I just bought a used ms250 from a guy. Wasn't sure what they had done to it. Found 2cycle oil in the bar oil reservoir. But can't get it to start. I'm guessing it's the carb. Also not sure it's even the right carb. The serial # is 262891917 . Does anyone know the correct part for the carburetor? I appreciate any help I can get.

How do you know it was two-stroke engine oil and why do you think it matters?

And what was in the other tank, the one closer to the handle? There should be a mixture of gasoline and two-stroke engine oil.

Why do you suppose it's a carburetor problem?
Have you checked for spark?

Can you describe how you try to start the saw?

 

[jesse916]

How do you know it was two-stroke engine oil and why do you think it matters?

And what was in the other tank, the one closer to the handle? There should be a mixture of gasoline and two-stroke engine oil.

Why do you suppose it's a carburetor problem?
Have you checked for spark?

Can you describe how you try to start the saw?

Yeah its got spark. When I dumped out the oil it was blue. It was just a guess. The chain moves so don't think it's a problem either way. I don't think it's getting any fuel
Starting it I put thr choke on and pull the cord about 3 or 4 times. It's has compression. But haven't tested to get exact reading..got it to pop once . Took the carb apart and the diaphragm looked a little worn. I'll try and attach a photo

 

[jesse916]

How do you know it was two-stroke engine oil and why do you think it matters?

And what was in the other tank, the one closer to the handle? There should be a mixture of gasoline and two-stroke engine oil.

Why do you suppose it's a carburetor problem?
Have you checked for spark?

Can you describe how you try to start the saw?

I figured the carb would be the first thing to replace. But it appears to be an aftermarket carburetor on it. And wasn't sure if they put the right one .

 

[HillyJohn]

The most likely thing with this saw is the previous owner treated it like a 2 stroke motorcycle, with 2 stroke oil in the oil tank, and straight gasoline in the fuel tank. I would remove the exhaust and look at the piston through the exhaust port. If it is scored with vertical lines, or there are aluminum deposits on the piston rings, then you are likely to have a saw with lack of lubrication damage that will not run with any carburetor.

 

[jesse916]

There is some scoring on the exhaust side. I was wondering if they just gassed it. Wich sucks because it's a nice saw. I didn't see any scratches on the intake side. I have done a pressure test to see how much compression it's getting. I just figured I try a new carb to see if I can get it to run at all. I just wanted to make sure i was getting the correct one. Even a 20 dollar anazon one. I have 3 other saws. I only paid 50 for it.

 

[jesse916]

The most likely thing with this saw is the previous owner treated it like a 2 stroke motorcycle, with 2 stroke oil in the oil tank, and straight gasoline in the fuel tank. I would remove the exhaust and look at the piston through the exhaust port. If it is scored with vertical lines, or there are aluminum deposits on the piston rings, then you are likely to have a saw with lack of lubrication damage that will not run with any carburetor.

Would it be worth putting in a new piston.,?

 

[epo]

There is some scoring on the exhaust side. I was wondering if they just gassed it. Wich sucks because it's a nice saw. I didn't see any scratches on the intake side. I have done a pressure test to see how much compression it's getting. I just figured I try a new carb to see if I can get it to run at all. I just wanted to make sure i was getting the correct one. Even a 20 dollar anazon one. I have 3 other saws. I only paid 50 for it.

And what was the result of the measurement?

 

[jesse916]

And what was the result of the measurement?

I sorry that was supposed to say I haven't tested it yet.. I have to dig out my compression tester . It should read no less than 110psi correct?

 

[epo]

I sorry that was supposed to say I haven't tested it yet.. I have to dig out my compression tester . It should read no less than 110psi correct?

It depends on how good a tester you have. For comparison, measure the pressure in your other running saws as well and see if it varies much.

 

[jesse916]

It depends on how good a tester you have. For comparison, measure the pressure in your other running saws as well and see if it varies much.

That's a good idea. Didn't think of that.

 

[jesse916]

That's a good idea. Didn't think of that.

I can feel compression, that's the only reason I was willing to buy it in the first place. But yes I need to get an actual reading. I did get it to fire on one pull. But that was it so far. Then pulled the plug and it was dry. I blew thru the fuel lines and cleaned the carb. Yet still no luck. But the diaphragm didn't look right. That's what led me down the path of just ordering a new carb. Until I saw there are a few different ones. And wasn't sure which one it was. Most things I've read say, zama c1q s76b but the ones I found have the adjustment screws close together. The carb I took off. They are spread apart. So wasn't sure which one was correct for this particular saw.

 

[JimR]

I can feel compression, that's the only reason I was willing to buy it in the first place. But yes I need to get an actual reading. I did get it to fire on one pull. But that was it so far. Then pulled the plug and it was dry. I blew thru the fuel lines and cleaned the carb. Yet still no luck. But the diaphragm didn't look right. That's what led me down the path of just ordering a new carb. Until I saw there are a few different ones. And wasn't sure which one it was. Most things I've read say, zama c1q s76b but the ones I found have the adjustment screws close together. The carb I took off. They are spread apart. So wasn't sure which one was correct for this particular saw.

You should have around 150psi. It sounds like somebody straight gassed the saw. You should be able to clean up the cylinder if it isn't scored badly.

 

[stihltech]

You guys and your compression gauges. Picture of the piston please for starters.

 

[HavinFun]

Yes, spend a few bucks to fix the saw. Usually go for $200-250 used. Pull plug and put a little mix in there, and if it lights off, great. If scoring is not too bad, just wondering if running 16 or 20:1 would give it enough extra lube to delay a rebuild? I like mine, but finicky on gas - should be fresh. I’ve gotten used to limboing withe the 592XP with 28” bar - not bending over as much. Prefer to use the 250, but finicky.