July 12, 2010
Too hot to ride today so I decided to take my zuma motor apart. I remeasured my ports and decided to open them up a bit. I looked at the port tunnels on the cylinder and realized that I would not meet my goals with carving. The exhaust port is already at 60% width and I have not done much to make it wider. When I got done with my files the exhaust port is now about 24.6 mm from the top of the cylinder. It is about a mm above what I was running prior. I used my files and worked for several hours on smoothing the ports. I could reach all the way into the transfers. My transfers went up half a mm to 32.5. The left side was .5 mm lower than the right. I did my best to equalize.

The problem that I am encountering is that the tops of the port tunnels are very close to the stock port figures. I decided that I would add a second base gasket to increase mean port timing and remove material from the top. My stock squish was 1.4 mm. I removed some material from the cylinder head. I didn't get enough removed and my squish is now 1.7 but better too much as I can cut off more. I am going to take it to about .8mm.

I have been running 24 grams on the stock variator. Too much right now, the bike is a dog until 33-35 mph then rockets past the speedometer stop. I didn't use my GPS as I figure I need more static compression. I may need to go back to my 19.5 (total) gram set of weights. I am hoping that getting the compression back up will do a lot for mid range. That is my next step.