MS210 sticks or locks up at BDC...

Guy just dropped off a MS210 that I thought was a lean seizure...Could not pull over w/ the recoil...The piston was at or near BDC and I could not see it w/ the muffler off...Pulled the recoil and put a socket on the flywheel and it broke loose w/ no problem...The piston is clean, but the thing catches everytime at BDC...Has anybody ever had this problem or can point me in the right direction before I tear it all the way down?...Thanks in advance...

Dump some WD40 into the cylinder. If it frees up, run it till it dies. Either have a spot where the rings are hanging up or the bearings are toast.

Had a similar situation with an 021.The ball bearing spacer had failed and the balls were getting together in a "wad" and locking up the crank.Look into the intake side,if the spacer failed,the intake side of the piston will be severely gouged while the exhaust side will look fine.The top of the piston should be badly pitted as well.
The good news is,the cylinder should be OK even though the piston is trashed.

HimWill said:

Had a similar situation with an 021.The ball bearing spacer had failed and the balls were getting together in a "wad" and locking up the crank.Look into the intake side,if the spacer failed,the intake side of the piston will be severely gouged while the exhaust side will look fine.The top of the piston should be badly pitted as well.
The good news is,the cylinder should be OK even though the piston is trashed.

Click to expand...

Just blew all the crap off of it...I will go yank the carb and look...There is no play in the crankshaft when you rock it back and forth?...

Intake side looks great...There is a little bit of carbon on top of the piston, but I would not say excessive...

I could turn mine over slowly,and it seemed smooth.If you spun it over fast,the ball bearings would bunch up together and bind the crank.Shine a light into the plug hole while looking into the exhaust port,see if the top of the piston is pitted.If so,I'll bet it is the clutch-side bearing that failed.A new piston,crank bearings and seals and you're good to go.

It does not matter if I roll it over slow or fast...It hits that spot and it stops...I can roll it over again w/ a socket, but the second it get there it get tight and stops...I think I might throw it back together and roll it back and try to start it...

There could also be some foreign object or metal bits embedded into the crankcase bottom that the rod will hit on its way down to BDC. I have come across this a couple of times.
Pioneerguy600

If you look into the exhaust port and see this:

The bearing will probably look something like this:

outdoorlivin247 said:

It does not matter if I roll it over slow or fast...It hits that spot and it stops...I can roll it over again w/ a socket, but the second it get there it get tight and stops...I think I might throw it back together and roll it back and try to start it...

Click to expand...

How comfortable are you with pulling the cylinder? From what your saying, either you have bearings that are toast (not expensive but not simple to replace), something in the botton of the crank housing, a spot the rings are hanging. You can sort it out rather quickly with the cylinder yanked.

Another quick thought, have you removed the clutch?

Do not try to start it until you find the problem!

Remove the recoil housing and see if anything's hitting in there.

It start and runs..It has to be a bearing or a bottom end issue b/c it makes noises I have never heard...Guessit is time to tear it all the way down...

blsnelling said:

Do not try to start it until you find the problem!

Remove the recoil housing and see if anything's hitting in there.

Click to expand...

To late...I am thinking you should have posted that about 20 minutes ago...

Is it possible that there is something behind the flywheel hitting? I'll shutup and go back to sleep now.

Anybody ever seen a wrist pin or rod break in one of these...Alls that I can say is not good...The piston is no longer going up and done w/ the crankshaft...It di not happen until after I pull the muffler and carb again, so hopefully it did not get into the cylinder...

Just a little more so you guys don't think I am a total idiot...He already took it to the Stihl dealer and they said it was junk...He was going to just give it to me, but I said I would look at it and see if it was an easy fix...The ADHD is not treating me good tonight...SLOW DOWN....

Let me guess. Someone tried to either remove the clutch or the flywheel nut, and after that it wouldn't turn over. Yes, I've seen it before and it looks like this. Your rod was hitting the bottom of the cylinder wall.

He said it has always been serviced by the dealer and this has happened to it once before...If I have to guess that is what I would have found...Now I am not sure what I am going to find...

blsnelling said:

Let me guess. Someone tried to either remove the clutch or the flywheel nut, and after that it wouldn't turn over. Yes, I've seen it before and it looks like this. Your rod was hitting the bottom of the cylinder wall.

Click to expand...

Not everyone destroys the rods multiple time when bustin down a little clamshell saw. Actually, only you that I know of.

Bowtie said:

Not everyone destroys the rods multiple time when bustin down a little clamshell saw. Actually, only you that I know of.

Click to expand...

Whatever! Multiple times? What are you talking about? Are you going tell me that's a strong rod design too? I'm not one bit ashamed to show my work. I can go over this again for you if you want. That piston was held in place with a piece of rope and I attempted to remove the flywheel nut with a scrench. You can debate all night long if you like about the proper rod angle the piston should be at with a piston stop if you want. Bottom line, it's a weak design.

blsnelling said:

Whatever! Multiple times? What are you talking about? Are you going tell me that's a strong rod design too? I'm not one bit ashamed to show my work. I can go over this again for you if you want. That piston was held in place with a piece of rope and I attempted to remove the flywheel nut with a scrench. You can debate all night long if you like about the proper rod angle the piston should be at with a piston stop if you want. Bottom line, it's a weak design.

Click to expand...

Weak design, maybe. But I have yanked a LOT of them little bastards apart and never had a problem or a bent rod. I have some spares if ya need them.