OS 55AX Repair

[Carl Finch]

I have broken the carb socket and need to replace the crankcase, but cannot remove the con rod from the crankshaft in order to remove the piston, even though the cylinder is out.  The con rod big end is in a trough machined into the crankcase.

 

Any suggestions or reference articles appreciated.

 

Carl

[Brian Lambert]

Hi Carl. Cylinder liner removed (I assume you have done that) piston at top dead center should give enough room to remove the con-rod from the crank pin if the crankshaft has not moved rearwards. Can you post a photo?

Brian 

[Engine Doctor]

Hi Carl , Brian is right the conrod should slide back when the piston is at TDC . Sometimes  if the little end bush is a sticky fit on the gudgeon pin it will be difficult to slide back and clear the crank pin. A little warmth can help from a hot air gun or similar .

[Aslan]

Hello Carl. Not sure if this is of any help. On the 70FS you have to remove the liner which leaves 2 holes on the cylinder visible, and from there you remove the piston pin, then the piston, and then the con rod from the crank. The rod can not be removed from the crank while connected to the piston. Not familiar with the 55, but normally the rod is easily removed from the shaft while connected to the piston, unless there is a more awkward way.......... which O.S. used on the 70FS. Again just throwing it out there in case they used this "pain in the butt" on the AXs.  

Edited By Aslan on 26/10/2010 12:02:38