Hi Roelof

The way that I modifiy the crank, I do as instructed by other editorials. The closing edge of the inlet valve is knife edged, but so is the opening end = increasing the over-all opening. Because I only go as far as to the edge of the port, and not over the edge...ie, not extending the original parameters of the outer casing, is this still increasing the duration...? The port is opened up more, but it is in the original outer limit.....? Also I ground the crank cheeks extra centrifuge's to create more turbulance and crank case pressure. I have really noticed a huge difference and the exhaust exits very strong and fast stream of smoke. The response is very crisp and snappy. Im still running the engine in, but after one tank on low rpms, the cooling head didnt even get above 60 degrees temp. I was amazed. I also match-ported the inlet port to the carburettor and ported the sleeve as well. In addition to this, I ground out the transfer channels in the crank case to match the ports on the sleeve, as I find that most engines are not properly done. This engine is a SH CXP.28-P6. Im now experimenting with an Associated Pro 8.0 .50, seeing if I can get some more RPM's out of the torque monster. If I cant, then at least it will be more responsive and have more power. I widened the exhaust port just as you said, but this time Im trying something different with the crank cheeks, not so cut up. But I know that I wont get the same crank case pressure as the previous engine I did. I actually cant believe how well that little engine absolutely pumps the gases out....!! Thanks for all your advice, I have learned to much and this is heaps of fun on my rainy days....!!!