Reply To: Neptune magneto question(s)

[tibor]

Could someone please double check this?

I took the head and the cylinder off, it looks like that from the ports to the top of the cylinder it’s 28 mm. The diameter of the cylinder is around 39 mm. So that is a volume of ~33.5 cm3. (The piston is pretty much flush with the end of the cylinder at tdc.)

I measured the volume of the head by the sophisticated method of pouring water into it and measuring the weight of the water (at 1 g / cm3), came out 13 g = 13 cm3.

So head + cylinder is 46.5 cm3 (2.84 cubic inches, matches the spec of 2.87 pretty well), the head is 13 cm3, that means the max theoretical compression ratio of 3.57. 1 atm = 14.7 psi, so I guess in theory one could not see compression higher than 52. So I guess my numbers were not that bad at all.