I opened them up at the outlet about 2mm, didn't touch anything else other than cleaning up the casing shift lines with a 180 grit cartridge roll.
The valves for the exhaust are going to be 1mm oversize, 30mm. I will end up having to blend the new valve seat again after it has been replaced and cut to the new size.
For now I am content with the way the ports are shaped so I went ahead and polished them. After the initial carbide bur shaping/enlarging and the 180 grit cartridge roll, there were a few more steps to get to this;
Another 220 cartridge roll on the die grinder then it was on to hand polishing. Wet/dry 320, 400, 1000 then 2000 grit. Finished off with a hand buff with green rouge then finally a white rouge.
There are a few light spots the could use some touch-ups but I think this should do.
So now in addition to having the intake ports with a rough textured surface to promote good flow. I have the rest completely polished to promote cooler combustion chamber temperatures. Heat will be reflected out the exhaust ports. Polished pistons and combustion chambers in conjunction with the exhaust ports will help maintain the temperature of the exhaust gases further out the exhaust track. In turn hopefully increasing the exhaust velocity and increase the scavenging effect. We'll have to wait and see..... Also it will reduce carbon buildup.
Piston Tops
Combustion Chambers
Exhaust PortsStay tuned for more......