Topic: 750 F2 pistons

[Old Moe Toe]

I recall reading on this forum somewhere that the pistons in the 750 F2 bikes have domed tops to suit the larger combustion chambers.
The pistons in the motor I am pulling apart do not seem to be domed although the heads are definitely F2 with the larger valves.
Following pics show the pistons in the motor (1st pic).
Have got a box full of other sohc 750 odds and ends including some pistons that have more of a domed top (2nd pic) but am not sure if this is the type of piston that should be in there. (3rd pic shows it a bit more side on)
If anyone has got a picture showing a F2 piston I'd sure be interested to see it.
Thank you.

[70CB750]

[70CB750]

These pistons are from 1978 Supersport - aka Red.

[bryanj]

Its a looong time since i stripped an F2 but non of those pistons in op's post look correct to me. Could the head have been "worked" and bigger valves fitted

[Old Moe Toe]

Its a looong time since i stripped an F2 but non of those pistons in op's post look correct to me. Could the head have been "worked" and bigger valves fitted

Hi Bryan. The engine number suggests the bike is an F2 so I am assuming the head is the F2 type as well. However I have never pulled on of these apart so am a novice. First 2 pictures show the combustion side of the head.
As for the pistons I am also a novice, it is just that I'd read somewhere the F2 type had a domed top.
In BrandEN's "Leak free top end" Sticky thread on this forum he says his bike is an F3 and his pistons in that thread look really domed. 3rd picture (lifted from his thread).

[bryanj]

First one i had to strip was a p/ex bikethat i used to go to Isle of Man, started with 350 miles per pint of oil and whilst on island top speed of 100 lots of smoke and 150 mpp so came home early expecting to find bad piston/rings but it was shot exhaust valve guides, this bike was about 2 years old with 20000 miles so no warantee.

Remeber the pistons being domed but cant remember how much, i think there was 410 in raised lettering by pin holes with earlier one having different numbers.

Is it standard or oversize? If os could wrong pistons have been used?

[seanbarney41]

Brandens bike was high compression 836 not sure what brand