@JEsse, no problem
@bkurb, its the first time i work with this kit. I know most of the guys in holland fit a simonini or an leovinci exhaust on it. Mostly with a carburator diameter of 15 - till 21mm. A 15mm bing works great for street-use but if you want to go faster, you can enlarge intake port to fit a 21mm dellortho. It`s important then to have a good clutch, because you loose low end power.
I use the kit for a circuit-race-puch, so its important to go fast on top, and accalerate good out of the corner. Therefore i calculate an exhaust.
i dont really understand what you meen with port pinging. Do you mean detonation?
I have added 2mm between casing and cilinder to set the timings of the transfer good. I wanted an exhaust timing of 180 degree with a blowdown of 25. De transfer ports had to be on 130degrees then. I have special tools to adjust timings of the transfer ports, but this is much easyer. How higher you raise the cilinder from the casem the higher the timings of the ports will be. Also the tranferports are big anouch to rev very high and gives good power.
You can raise the cilinder by adding more gaskets, or making a 2mm spacer from alumium or metal.
The main problem will be te cilinderhead. The space betweed cumbustion chamber and piston will be 2mm greater too. In that case the compressionratio will be too low for the engine to run fine.
My solution to that, is making a cumbustion chamber that falls in 2mm into the cilinder.