Thanks a lot!FertBert wrote:Ok, I made a port map of the cylinder I have. It has a dual ring piston, I'm not sure why the link I posted has a different piston.
I've placed them together in this post for a good comparison:
I think you're right. To bad you didn't measure the distance from the top of the cilinder to the top of the cylinder skirt transfer.FertBert wrote:The exhaust port seems to be a little bit more aggressive than the one on the DR. I also calculated the area of the boost/transfer ports on the Mer Eur kit and the DR.
DR = 434 mm squared area
Mer Eur = 556 mm squared area
This is probably due to the fact that the bore or size of the Mer Eur kit is slightly bigger than the DR.
But assuming that we both made no measuring-mistakes it is likely that the Mer Eur gives max power at a higher RPM than the DR. I guess the Mer Eur cylinder is likely to give max power between 7.000 and 8.000 RPM, while the DR gives max power between 6.000 and 7.000 RPM.
[I base this on the theory of A. Graham Bell's Two Stroke Tuning, but I need the distance from the top of the cilinder to the top of the cylinder skirt transfer to confirm my assumption.]
By the way: notice that the Mer Eur has much widener transferports than the DR (17 + 9 mm vs. 11 + 8 mm). This already makes a difference of 98 mm squared area...