044 10mm or 12mm piston problem

[emathews82]

Hi all,

I've got an issue an trying to get to the bottom of. I picked an 044 off craigslist; mostly there but missing some stuff. The previous owner allegedly rebuilt the bottom end and it looks like he did, I can see new gasket and bottom end bearings feel good. He said he he ordered a 12mm piston kit for it, it didn't fit and he never got back to it. The serial number starts 125 so this ought to be a 10mm wrist pin saw. I got a 10 mm pin piston kit and bearing and went to install and the piston bearing is too small for the bore in the connecting rod. The connecting rod is marked 1128 and also has a "B" up on the small end. The bearing for the 10mm pin piston is 10x14x13. The bore in the connecting rod appears to be 15mm. I have a 1 mm discrepancy. This is measured using a tape, in inches and converted but 15mm is my best measurement right now. I have 3 questions then;

Does anyone know the O.D dimension on the 12mm wrist pin piston bearing?

Could there be the wrong connecting rod in the saw?

I read somewhere that the piston pin bore changed from 14mm to 15 mm, is that the same change as the 10mm to 12mm pin?

and a 4th question;

whats going on here?

 

[bluestripes]

The dimensions of the 12mm bearing are 12mmx15mmx15mm.

Could be he put a different crank in it then he rebuilt the bottom end. Just a thought.

 

[pioneerguy600]

Evidently you have a 12mm pin connecting rod and crank, did you try the pin from the 12 mm piston in it? Cranks can be interchanged between the 10mm early and 12mm later saws.

 

[emathews82]

Evidently you have a 12mm pin connecting rod and crank, did you try the pin from the 12 mm piston in it? Cranks can be interchanged between the 10mm early and 12mm later saws.

The saw was without a piston and bearing when I got it. The seller claimed he tried a 12 mm pin piston and it didn't fit. I was going off that information, foolishly. I'll try the 12 mm.

 

[pioneerguy600]

The saw was without a piston and bearing when I got it. The seller claimed he tried a 12 mm pin piston and it didn't fit. I was going off that information, foolishly. I'll try the 12 mm.

Yes, try the 12 mm pin and piston and let us know how that how that goes.

 

[emathews82]

meteor or NWP

is the meteor piston worth the extra 20 from Bailey's?

 

[Steveo_supremo]

Yes.

 

[emathews82]

what is a pop up piston? what is squish?

 

[a. palmer jr.]

what is a pop up piston? what is squish?

Since you're asking that, let me give you some advise. If I were you I wouldn't try to build any more compression into that 044 than what it will have when stock, especially if it doesn't have a compression release. Mine has gobs of compression and must be drop started and it's not been modified as far as I know. Kinda hard on those little starter pawls too.

 

[emathews82]

After ordering the meteor piston from bailey's and getting the piston pin/wrist pin bearing locally i've got the proper parts now collected. Dry fit confirms that the saw has the 12mm pin crank in it. So, to clarify, a 12mm pin bottom end (crank and rod) can go in an older 044 with the serial number starting with one? And this could only happen as a pair (crank and rod)? The big end bore on a 12mm and 10mm pin connecting rod are not the same?

Tonight i'm going to get the saw re-assembled. I have a question about the cylinder gasket, does the profile/ridge pressed into it go up or down? Surely a question befitting of my rookie status but better safe than sorry. thanks!

 

[a. palmer jr.]

After ordering the meteor piston from bailey's and getting the piston pin/wrist pin bearing locally i've got the proper parts now collected. Dry fit confirms that the saw has the 12mm pin crank in it. So, to clarify, a 12mm pin bottom end (crank and rod) can go in an older 044 with the serial number starting with one? And this could only happen as a pair (crank and rod)? The big end bore on a 12mm and 10mm pin connecting rod are not the same?

Tonight i'm going to get the saw re-assembled. I have a question about the cylinder gasket, does the profile/ridge pressed into it go up or down? Surely a question befitting of my rookie status but better safe than sorry. thanks!

I always put those kind of gaskets with the raised portion up. I don't really know if it makes that much difference since some people run saws without a gasket. I recommend a gasket on this one, however.

 

[emathews82]

next assembly question; The rings have a bevel in their ends, do I install long point or short point up?

 

[emathews82]

I've been putting a few drops of two stroke oil on parts before assembly, I figure it can't hurt. Any other tips/techniques to a top end an experienced mechanic may care to lend me?

 

[jockeydeuce]

next assembly question; The rings have a bevel in their ends, do I install long point or short point up?

The long end of the rings should go down....It's pretty self evident when you look at the location of the locating pins in the ring groove.

BTW.....All Stihls made in Germany have a serial # that starts with "1".....It's the rest of the serial # that is looked at to determine if you have a 10mm or 12mm saw.

 

[emathews82]

thanks jockey. I'm taking notes.

 

[emathews82]

another question for the field; I spun on the clutch and tightened it down against some cotton rope fed through the spark plug hole. I assume a piston stop tool is more recommended but this is what i've got right now. When I put the clutch drum on and align it with the oiler spring I can't seem to get enough room to get the washer and the E-clip onto the crank shaft. The only way it fits is to remove the plate that sits over the oiler; between it and the clutch. Is there any way the 12mm wrist pin crank assembly is causing this problem? Can the saw be run without that plate? Thanks again for everyones help and feedback.

 

[Jacob J.]

There were different clutches for these saws and the different clutches have different "spacer" plates that go behind them.

If this was an original 10mm wrist pin saw that someone stuffed a 12mm pin crank into, then you may run into fitment problems
with the early clutch and spacer plate. You can run the saw without the spacer plate behind the clutch. If you can't get the clutch
drum, rim washer, and e-clip all on then that's an indicator to me that you need to take the spacer out.

 

[rupedoggy]

There were different clutches for these saws and the different clutches have different "spacer" plates that go behind them.

If this was an original 10mm wrist pin saw that someone stuffed a 12mm pin crank into, then you may run into fitment problems
with the early clutch and spacer plate. You can run the saw without the spacer plate behind the clutch. If you can't get the clutch
drum, rim washer, and e-clip all on then that's an indicator to me that you need to take the spacer out.

Or turn it around

 

[emathews82]

What is the intent of the spacer behind the clutch? I came to the conclusion that the spacer may not be imperative. Is there a clutch that would fit this frankenstien rig that would allow me to use the spacer? If Im not at risk of burning out the oiler by taking out the spacer I'm not gonna worry about it though.

 

[emathews82]

on an off note where where should i post a request to buy a vintage part from a member? Looking for a fuel line for a Mcculloch 1-71.