actual displacement of 80cc kit(well almost actual)

so you are talking about the extra space between the piston and in the dome of the head being added to the cylinder displacement?
 
Not to start a bigger fight with this....

But to my reasoning, an 80cc HT is actually 65.92cc

That is how I was taught to measure volume in terms of displacement.
 
ok hough what about this,take the head off remove spark plug,drop the piston just a little from tdc fill the void in the head with clay and enough to fill down through the gasket to the slightly lowered piston then reinstall the gasket and torque the head down,turn the engine back to tdc excess clay will come out the plug hole then remove head and collect the clay minus what was in the plug hole and measure the volume of the clay then add that to the displacement reading
 
I read somewhere that if you add the swept volume (bore x stroke) and the squish band, you end up with a "cylinder capacity" of close to 80cc. Someone even mentioned that the "effective displacement" is even less because they were only counting the part of the stroke when all ports are closed. (making things even more confusing!) It doesn't really matter to me whether it is a "true" 80cc, as long as it is bigger than the "48cc" engine. I am happy because I got an engine with more displacement. They all cost the same anyway, so I don't see what the big deal is. We're talking $99 bicycle engines, not $15,000 Harleys.
 
dazed_maunder said:
ok hough what about this,take the head off remove spark plug,drop the piston just a little from tdc fill the void in the head with clay and enough to fill down through the gasket to the slightly lowered piston then reinstall the gasket and torque the head down,turn the engine back to tdc excess clay will come out the plug hole then remove head and collect the clay minus what was in the plug hole and measure the volume of the clay then add that to the displacement reading
Click to expand...

You could do the same thing with water, or a heavy oil. Less chance of an air pocket, and you could do it without pulling the head off
 
Drunkskunk said:
You could do the same thing with water, or a heavy oil. Less chance of an air pocket, and you could do it without pulling the head off
Click to expand...

it would be harder to collect,i know they measure the volume of heads with heavy oil or some sort of sand but thats when the head is off and that wont include the gasket space and the space the piston crown takes up either way this has turned into something it wasent supposed to be i gave a cc measurement based on the way most if not every engine is measured for displacement or volume (same thing) as for they might be different because there chinese or what have you i do believe a dirt bike from china would have the same cc reading as one made in the us either way i still am curious to see if the displacement plus the the combustion chamber volume would actually add up or even closely add up to the manufactures cc rating
 

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