machining cylinder head
Posted: Sat Sep 03, 2011 3:47 pm
doing a stg 4 for friend.
the head has a volume of 15cc and the squish as std 3.1mm .
std comp ratio on this is 8.7:1, on my lambretta I have always aimed for 9:1 std and 6:1 corrected
I have jacked the cylinder up 1.7mm so now squish would be 4.8mm if head is left as is no good at all ,but if i machined the head to sit 1.3mm inside the cylinder ( as in the article) squish will be 2.1 mm still big .
So do I reduce squish to 1.5mm and open up the combustion chamber or just run a large squish , which runs cooler and more reliably?
Paul
the head has a volume of 15cc and the squish as std 3.1mm .
std comp ratio on this is 8.7:1, on my lambretta I have always aimed for 9:1 std and 6:1 corrected
I have jacked the cylinder up 1.7mm so now squish would be 4.8mm if head is left as is no good at all ,but if i machined the head to sit 1.3mm inside the cylinder ( as in the article) squish will be 2.1 mm still big .
So do I reduce squish to 1.5mm and open up the combustion chamber or just run a large squish , which runs cooler and more reliably?
Paul