I thought I would share some of recent work.
I bought a "factory race motor" from Tory on ebay. Thanks Tory. So far seems like a good buy. I checked compressor before disassembly and it had 150psi both cylinders. Inside looks good. Exhaust and transfer ports raised from stock. What is most interesting is the intake is widened to except 44mm carbs. This seemed impossible until I realized the intake casting is different from stock invader - its bigger.
I have decided to do a little extra porting, buy aaen race pipes (not the trail versions on the web site) and drop it into a liquifire chassis I have. The extra porting is to remove the web/divider in the top case transfer port, and shape the cylinder transfer web/divider to look like the 4/6 equivalent. see attached pics. I still have to do some light clean up, but the heavy grinding is done. The cylinder pic shows stock invader, left, my port work middle, and stock 4/6 right.
Need some input - I have been using winderosa gasket kits. the drive side seal has a wider than stock raised area that doesn't quite fit in the indent. I bought a separate seal from Dennis Kirk for this seal and its a two piece. see pic stock seal on the end, then 2 piece seal, then Winderosa seal installed. Anyone have experience with this.