Piston orientation

[Gannet]

I have been a bit silly. In removing the piston from the con rod on my Forty, I didn't make a note of which way round it goes - it seemed obvious at the time. Now however on re-assembly it isn't obvious!
Does the high 'step' part of the piston crown go by the inlet or exhaust port?
Thanks.

Jeremy

[Keith.P]

Its not as daft as it sounds, the step part, as you say goes at the top (inlet), don't know what motor you are working on, but some small ends should only go one way around as well, they have a hole at only one end.

[Gannet]

Thanks for that info. I haven't removed the gudgeon pin from the piston, so that was one part I couldn't muddle up.
The motor is an FV.
Cheers

Jeremy

[Niander101]

the high 'step' part of the piston goes next to the inlet as it deflects the charge up toward the head and not out through the exhaust port
basic 2 stroke design

i don't see how it matters about the pin
but maybe someone can enlighten me

[Keith.P]

I remember something about some gudgeon pins are made as a tube but with one end blocked off and because it passes the ports, I think.
So with the hole at the top it could fill with fuel, that's what I was thinking anyway, getting old you see, its all getting a little vague, you never know I maybe right and this could be the first time.