MS 250 stuck

[eonk]

I recently tried to start the saw and the pull cord wouldn’t come out. I removed the cord and it worked fine. When looking for the problem I tried to remove the chain sprocket and it won’t budge. I suspect that the bearing broke and the pins are jammed in the sprocket. Any suggestions on how to remove the sprocket? Yes, I did remove the e clip and the washer.

 

[Woodtroll]

The sprocket should be loose even if the crank is seized. Sounds like either the chain brake is on, stuck, or broken. Or possibly the clutch was overheated and melted the case around the sprocket, if the brake was left on at high idle. Could also possibly be gummed up if you had biodegradable bar oil in it that sat for a long time. But my first look would be at the chain brake mechanism.

Good luck!

 

[eonk]

The sprocket should be loose even if the crank is seized. Sounds like either the chain brake is on, stuck, or broken. Or possibly the clutch was overheated and melted the case around the sprocket, if the brake was left on at high idle. Could also possibly be gummed up if you had biodegradable bar oil in it that sat for a long time. But my first look would be at the chain brake mechanism.

Good luck!

Thanks. I will try that

 

[hacskaroly]

I suspect that the bearing broke and the pins are jammed in the sprocket. Any suggestions on how to remove the sprocket? Yes, I did remove the e clip and the washer.

Most likely if the needle bearing broke (likely melted, the cage is usually plastic) then all of the pins would most likely just fall out and the sprocket would be loose. If you have a pair of channel locks, you can grab the sprocket and rock it or try to spin it. This may loosen up or break up what's holding it in. Like @Woodtroll stated, could be locked in by the chain brake.

Take a picture or two of what you are dealing with, we might get a better idea of what you are dealing with and have a better idea of what to recommend. Is the plastic around the clutch opening melted at all? I have seen this issue with the MS 271, crap gets behind the chain brake causing the brake spring to rub against the clutch then overheats the area and melts the surrounding plastic.

Also, welcome to the forum!!

 

[eonk]

The brake is frozen and the plastic melted around the sprocket. I was able to free the sprocket with some effort. I now have to determine why the brake is frozen. Thanks for the advice.

 

[hacskaroly]

The brake is frozen and the plastic melted around the sprocket.

Its possible with the melted plastic it has melted enough around the chain brake spring that it is holding it in place, preventing it from opening or closing. Might be one of those where you will need to get a new crank case and just move all the parts over to the new crank case. I have two 271s with this issue, I have moved all the parts for one over to the "new" used crankcase, I just need to get a second crank case to move the parts from the other.

I would be willing to bet with yours, enough saw dust, chips and bar and chain oil got behind the cover and ended up pushing the chain brake spring against the sprocket drum and while running this created excessive heat that caused the melting of the plastic around the sprocket and around the chain brake spring too.

eBay has some relatively cheap options if you decide to go with a new or used crankcase:

 

[hacskaroly]

Did you unscrew the two screws (circled in red) and take off the cover plate? If not this will give you access to the entire chain brake and you might see what is holding it up or causing it not to move.

 

[hacskaroly]

Here is what my 271 ended up looking like, that isn't bar and chain oil and crud, that is burnt plastic. I tried to shave out enough of the bad stuff to get the chainbrake to sit even and work correctly, but it didn't work, so I swapped everything to a new crankcase.

 

[eonk]

Here is what my 271 ended up looking like, that isn't bar and chain oil and crud, that is burnt plastic. I tried to shave out enough of the bad stuff to get the chainbrake to sit even and work correctly, but it didn't work, so I swapped everything to a new crankcase.

View attachment 457781

Thanks for the advice. Fortunately, my brake is still moving freely. There was a very small amount of plastic melted around around the edge. I haven’t found time to explore why the brake won’t release. Everything moves freely if I remove the brake around the clutch.

 

[Woodtroll]

Sounds like you're on the right track, and the damage may not be too bad. Good news, and good luck!

 

[Stump Shot]

At times a ring of crud can build up on the inside of the drum, just behind the clutch, if cooked on good can make it very hard to remove. About the only thing I know id to grab it with a pair of pliers and pull straight on it until you can get it through that crud line. Once removed and if not excessively worn, it can then be mechanically cleaned and reused.