machining cylinder head

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paul213
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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
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Main scooter: vespa polini220/gts 300
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Your a very lucky man! This is an update to the stage 4, 2.4 squish - volume 23cc....don,t tell anyone
paul213
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Joined: Wed Jan 07, 2009 11:22 am
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is this what you have got on yours or what you have been told to aim for by someone?
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