SOHC carburation and setting up

[James Bowen]

Guy,

Hello, OK understood about the port shape.

Yes I think your right. In terms of the development of the current setup, and by this I include the current cylinder head and cam configuration. There are no other gains to had by "fine tuning".

Compression ratio, you've alluded to. I worked it out thus:

CC'd volume of cylinder head (measured with syringe, oil, and plate of glass) = 28.5cc (yes I skimmed the head! - I know)
CC'd volume of piston cutouts = 5cc
Block decked 0.5 mm pistons pop up into gasket. Gasket 1.6mm compressed thickness = 6.4cc
Ring land in between piston and block = 0.5cc
Total = 40.4cc

CR = CC volume + Swept volume
CC Volume

CR = 10.3 :1


I would like to do exactly what you suggest, take it apart, and get the flow and valve response and cam all anaylised to see what is going on. But. Despite not producing the power or torque I would like, it is reliable and still fairly rapid, and gives me a lot of enjoyment. I shall in the next year, start to build another engine, employing what I have learnt since I built the current engine (mostly from this site through various posts by you and other knowledgable members). In the meantime, Ill put this threat to bed I hope that it will continue to provide some guidance to other members, if only how not to build an engine ! - Many thanks Guy

Kind regards,
James