Piston pin toConrod fit ??

Marchless · Post by **Marchless** » Fri Mar 25, 2011 10:01 pm

Rebuilding my Engine 500 Twin G9 1959 .How tight a fit should the piston pin be to the conrod (small end) With the piston pin in the vice the conrod falls under its own weight and the pin is a very firm fit. Iam just a bit worried its a bit tight and might sieze when hot

Eric · Post by **Eric** » Fri Mar 25, 2011 10:11 pm

Sounds OK to me the Gudgeon Pin is just about as tight as it can be and still allow rotational movement. It usually needs the piston and con rod to be warmed up just to get it out or back in so dont worry.

Marchless · Post by **Marchless** » Fri Mar 25, 2011 10:20 pm

Hi Eric Thank you for a quick reply and the reasurance .I would rather find out now than when its to late

g80csp11 · Post by **g80csp11** » Fri Mar 25, 2011 11:40 pm

The piston pin should fall under it's own weight through the small end of the conrod when oiled with light oil.
The pin it's self will be tight on the piston , and require the piston top be warmed when finially fitting the piston

iandusud · Post by **iandusud** » Sat Mar 26, 2011 7:33 am

Gudgeon pin should be a sliding fit in small end bush and an interferance fit on the piston requiring the piston to be heated in order to fit.

Ian