Sachs Cylinder & Piston specs.

[Mark Annan]

What are the wear limits for Sachs engines?  I have several Penton manuals.  They have excellent specs for everything but the cylinder and piston clearances and/or wear specs.  I have a couple genuine Sachs service books as well.  Same story.  The only specs I can find in print are from the Clymer Sachs Engine Service-Repair Handbook.  I know some generally accepted specs but I would like to know the "Official Penton" numbers.

Another Question:  I know how to determine the compression ratio of 4 stroke engines.  When figuring the compression ratio of two stroke engines is the entire volume of the cylinder used or just the portion above the top of the highest port?  Anyone know?

Mark    


 

[john durrill]

Mark on a 125 more than .0045 would make me very nervious.
 a new set of rings are usually a good bench mark. after you hone the cylinder to break the glaze, slip the new rings in and see what the end gap is. if its over the wear limit then rebore.
  Most compression figures you see listed for 2 strokes are figured with the full cylinder volume. i think it looks better to prospective buyers chuckle chuckle.
 I think i saw how to figure true compression on a two stroke on the Mc Dizzy site.
 their is a shortcut in the library, listed for port maping that should get you to the site. then go to the home page and poke around. i think you can find it there.
John

 

[Mark Annan]

Jon,

Thanks for the info.  I figured that was how it was calculated.  I'll check the other site and see what I can find.

Mark