Chainsaw Repair

So here's a question:  If the rpm of peak Delivery Ratio is dependent on case volume, does it also depend on combustion chamber volume?

I've been playing around with two 42cc Poulan engines with different combustion chamber volumes, and thinking about the impact of that.  Obviously larger combustion chamber volumes negatively impact compression ratio, but do they also trap a larger volume of fuel/air mix?

Clearly combustion chamber volume can't be zero or way too big, but what is optimal?

my understanding at this point, is that two factors control what ultimately becomes a motor's delivery ratio.  ie. case volume and porting.

in the first part of the paper on case volume, porting was held constant, while they tested differing case volumes.

i found another paper in which testing for delivery ratio was done by keeping the case volume the same, and changing porting only.
found here (starts on page 17):  http://www.vintagesnow.com/SledU_Folder/delivery_ratio-1.pdf

combustion chamber......so far, i have not found mention of this affecting delivery ratio.  i was not on the lookout for this while reading and may have missed it?

while this may or may not be completely true, my belief is the optimal case sizing has to match the porting sizing for a overlapping range of rpms to work well.  still learning on this.  read 4 papers on this so far, just slogging through it all.  two sources mention that delivery ratio is the most important factor for making power, for motors which lack a tuned exhaust.

thought the estimate i was working on for case size/rpm would have ended better.  the error between optimal and estimated, increases with rpm.  they are two straight line style plots.  could post it.  too bad it was not more accurate.