MS 250 Stuck

[Policy Peddler]

Young man told me last week that he lent out his Stihl saw, when the guy brought it back he said "i do not know what happened but it is stuck". He said sure enough it would not pull over. I told him to bring it over, which he did. When I got it, it pulled over hard, but it did turn over.
The saw is a MS 250
Checking the gas in it, there was no color marker, but it did feel like it had oil in it rubbing the gas between my fingers.
I put some Stihl synthetic through the spark plug hole and carburetor, did not help.
Is there someplace that tells how to take the cylinder off this saw?
Is the cylinder either good or replace it, no repairing it?
If the cylinder does need to be replaced is there something better than OEM to replace it with?
In this situation, what are the chances the rod and crank bearings are still good?
Any other feed back would be greatly appreciated.
thank you
Richard

 

[Rockjock]

Richard pull the muffler and look at the piston. I have had a saw like that come to me and it was thought to have been scored. The customer dropped it and the coil got pressed up against the flywheel. Pulling the muffler will let you see the condition of the piston. There is nothing better than OEM IMO. There are several videos on youtube on a ms250 tear down.

 

[alexcagle]

I recently had a locked up saw turn out to be a small nail that the flywheel magnet picked up out of the back of his truck. It ended up wedged between the flywheel and the coil. Also a screw that got tucked in a recess on the flywheel backside that got wedged tight between it and the crankcase. But those are rare lucky cases.

 

[Rockjock]

I recently had a locked up saw turn out to be a small nail that the flywheel magnet picked up out of the back of his truck. It ended up wedged between the flywheel and the coil. Also a screw that got tucked in a recess on the flywheel backside that got wedged tight between it and the crankcase. But those are rare lucky cases.

I like the lucky cases personally. I would like to have some more please!!!

 

[Policy Peddler]

thank you for your reply's.

 

[Policy Peddler]

will the 250 benefit from a MM? What has to be done to it?

 

[angelo c]

will the 250 benefit from a MM? What has to be done to it?

Yes, but some do not have the fully adjustable carb. Open up the muff to 70% of the exhaust port size and retune. Key being RETUNE correctly.

 

[Policy Peddler]

maybe i will just leave it.

 

[alexcagle]

@Rockjock: Me too!
I have a backlog of 65-85 saws at any given time. I can usually go through about 7-12 a day, depending on how many are completely roached out. It's fun to me, so it's not work! Lol
...
@Policy Peddler;
As far as fixing that MS250 if it's piston and cylinder are scored; I agree with @rock Jock, that oem is best quality. It is the most expensive as well.
Next best are Meteor, then Hyway Nikasil plated cylinder kits IMO. The bearings and crank rod big end can be flushed of contaminants with WD40, then blown out. If you take good notes and pics during disassembly, you can probably figure it out.
Just don't force things together on reassembly. Remember that all Stihls were designed with serviceability in mind.
Sometimes you can get away with dremel sanding the heat transfered aluminum off the hard chrome cylinder plating, if it's not too bad. Try a dremel #502 or #503 sand paper paddle wheel from Lowes or Home Depot, then all you would need is a new piston kit. If it wears through the chrome though, (which Is very tough stuff), or there is broken ring gouge in the wall of the cylinder, then it's new cylinder kit time.
The clamshell design of the 1123 series requires sealant to seal the two halves of the engine together.
Permatex Motoseal (most any auto parts stores keep it), Yamabond, or any similar compounds work very well. It is important that you apply a very thin coat as most of it will squish in and out when tightened. It's got to be clean and dry when applied. I use laquer thinner in a spray bottle designed to handle caustic sprayables, like a wd40 brand refillable type bottle. The laquer thinner reeks,and is flammable, so ventilate well. Getting brain damage or being on fire is probably not high on your list of fun things to do.
Be careful removing the factory sealant with a wire wheel on a grinder with the aluminum surfaces of the pan and cylinder. It is a precision fit surface to insure the bearings don't move in the crankcase, the seals are centered and retained, and it has an airtight seal.

 

[Policy Peddler]

use permatex flange sealant 518 on the case halves?

 

[alexcagle]

This is it: works great, and can be disassembled when dry.

 

[idiotwithasaw]

Ms250s are by far my favorite clam shell to disassemble. I've taken several apart. The only bad thing about them is that you have to strip it all the way down.

 

[Policy Peddler]

idiotwithasaw so you are saying send you the saw and you will fix it for the fun of it!

 

[idiotwithasaw]

U pay shipping and parts, sure. Lol

 

[idiotwithasaw]

Or I'll just sell you a running one. I've got a couple for sale.

 

[atpchas]

Young man told me last week that he lent out his Stihl saw, when the guy brought it back he said "i do not know what happened but it is stuck". He said sure enough it would not pull over. I told him to bring it over, which he did. When I got it, it pulled over hard, but it did turn over.
The saw is a MS 250
Checking the gas in it, there was no color marker, but it did feel like it had oil in it rubbing the gas between my fingers.
I put some Stihl synthetic through the spark plug hole and carburetor, did not help.
Is there someplace that tells how to take the cylinder off this saw?
Is the cylinder either good or replace it, no repairing it?
If the cylinder does need to be replaced is there something better than OEM to replace it with?
In this situation, what are the chances the rod and crank bearings are still good?
Any other feed back would be greatly appreciated.
thank you
Richard

Check your Inbox for a link to a shop manual for that saw.

 

[Policy Peddler]

Thank you

 

[Policy Peddler]

It is going to have to wait, 4 super charged motors my suburban transfer case and a super charger are apart on my bench now. No room.