pistons for 1968 40hp bigtwin

[lark2004]

Hi everyone, <br /><br />I am about to start re assembling my engine. I have just seen however, a replacement piston kit on the net that has big holes cut into the piston.<br /> http://www.powerheadkit.com/2_cyl omc.htm <br /><br />I guess that this reduces weight and friction. my question is how feasable is this to do to my origional pistons? They are still within spec for bore clearance and aren't out of round.<br />N.B. parts for these motors are not easly available in my part of australia any more.

 

[Chinewalker]

Re: pistons for 1968 40hp bigtwin

Hi Lark,<br /> Those pistson are not for your motor. They are to a much later 40hp loop-charged model. <br /> Cutting holes in your pistons will weaken them. Those old Big Twins are by their nature built a little on the loose side and the pistons tend to bobble around a bit in there. If you cut holes in the skirts of the pistons, you're likely to have a piston failure pretty quickly.<br /> If the pistons you have are still good, I would break the glaze on the cylinder walls with a hone, replace the rings with new (if possible) and put it back together. The bigger issue with those old Big Twins is carbon build-up, so make sure you've got the ring grooves cleaned out...<br /><br />- Scott

 

[lark2004]

Re: pistons for 1968 40hp bigtwin

fair enough, already honed, new rings are here, grooves are cleaned, just gotta get seals....