Stihl 261cm, I need some help!

[Stihlproincky]

Hi guys, this is the 261 I posted about a couple weeks ago, got a new piston for it today. This evening I put it back together, everything seems smooth with the p/c, but when I crank it, when it tries to start it "pops" and I mean it pops. It blows smoke out the muffler, seems like really high compression. I've done other rebuilds never had this happen!
What could cause this?
I put a little oil on the p/c could this cause this?

 

[thompsoncustom]

Hi guys, this is the 261 I posted about a couple weeks ago, got a new piston for it today. This evening I put it back together, everything seems smooth with the p/c, but when I crank it, when it tries to start it "pops" and I mean it pops. It blows smoke out the muffler, seems like really high compression. I've done other rebuilds never had this happen!
What could cause this?
I put a little oil on the p/c could this cause this?

OEM piston? Did you measure the squish?

 

[lone wolf]

Hi guys, this is the 261 I posted about a couple weeks ago, got a new piston for it today. This evening I put it back together, everything seems smooth with the p/c, but when I crank it, when it tries to start it "pops" and I mean it pops. It blows smoke out the muffler, seems like really high compression. I've done other rebuilds never had this happen!
What could cause this?
I put a little oil on the p/c could this cause this?

Well, a little oil won't cause that! Did you apply it or dump it in?

 

[stihltech]

How does it crank with the plug wire disconnected?

 

[Stihlproincky]

Well, a little oil won't cause that! Did you apply it or dump it in?

Applied it with my finger.

 

[lone wolf]

Applied it with my finger.

That won't cause the problem you described. What brand piston?

 

[Stihlproincky]

How does it crank with the plug wire disconnected?

Everything feels normal

That won't cause the problem you described. What brand piston?

stihl

 

[lone wolf]

Is the flywheel hey sheered?

 

[Stihlproincky]

up

Is the flywheel hey sheered?

how'd you guess? It was like that when I started working on it.

 

[lone wolf]

up how'd you guess? It was like that when I started working on it.

Well is it fixed ,what did you do ?

 

[Stihlproincky]

I did line it up though before I tightened it down.

 

[lone wolf]

I did line it up though before I tightened it down.

Check it again! And how did you tighten the nut on the flywheel?

 

[Stihlproincky]

Check it again! And how did you tighten the nut on the flywheel?

Double checked it last night, everything was lined up. Tightened with a wrench.

 

[lone wolf]

Double checked it last night, everything was lined up. Tightened with a wrench.

With the piston stopped, a rope or tool? Do you have a 3/8 impact gun? Maybe flooded check that.

 

[Stihlproincky]

With the piston stopped, a rope or tool? Do you have a 3/8 impact gun? Maybe flooded check that.

A rope, no impact gun. It did flood but I cleared it and it did the same thing. Flywheel is on tight though

 

[lone wolf]

A rope, no impact gun. It did flood but I cleared it and it did the same thing. Flywheel is on tight though

What's the history of the saw could that flywheel be off a non Mtron saw? Clean the plug or put a new one in.

 

[Stihlproincky]

What's the history of the saw could that flywheel be off a non Mtron saw? Clean the plug or put a new one in.

Cleaned the plug, I dunno but I highly doubt that.

 

[lone wolf]

Double checked it last night, everything was lined up. Tightened with a wrench.

Did you put a mark on it to see if it moves after tightening it or did you pull it apart to look?

 

[lone wolf]

Cleaned the plug, I dunno but I highly doubt that.

Does the flywheel have 2 magnets on it or 1?

 

[Stihlproincky]

Did you put a mark on it to see if it moves after tightening it or did you pull it apart to look?

That's genius! I pulled it apart and looked.