[33gold]

not sure is anyone has cc's an i.e head and piston dishes but.....

bore is 8.7mm so bore area is 8.7 x 8.7 x 3.14159 / 4 = 59.45 cm2
Volume of 1 cyl is bore area x stroke so; 59.45 x 7.2 = 428.04cc
Multiply this by 4 =1712cc which is ok

Now to calculate compression = (vol of cyl + comp chamber vol) / comp chamber vol so;
428.04 + 49.5 (from manual) / 49.5 = 9.64:1 compression

This is the same for carby and i.e. engine yet according to the manual i.e. is 9:1 and carby is 9.5:1

Does anyone know if the manual listed compression is dynamic rather than static as the chambers are the same for i.e. and carby?

To make matters worse I cc'd my heads and piston dishes (I have removed matarial as valves hit piston) and made these only 47.5cc = 2 cc less than std!

The issue is that just by reducing my head cc by 6cc I could hit 10.8 to one so a small amount gets a lot more compression. Do I play it safe with the manuals figures? Has anyone else cc'd and found such a big difference - I am sure that the heads have not been refaced.