Hello Boucher. First, this is to be a good-running street bike that closely resembles a Laguna Seca, but mainly with some upgrades to wheels (17-inch Technomagnesios) and rotors (300mm and 220mm floating). Years ago Gowanloch sold some very-complete LS fairing kits for the amazing price of $400US; I later found a near-new solo seat for a LS, and will use a NOS F1b tank. The F3 400 frame is identical to the LS frame (mainly the muffler hangers). This bike will be for going to the café, to sip a latte (a very short rhyme).
It will not be a WSBK winner, or a club racer, or even a track day bike. So, the engine plans are more humble. The valves are now 41/35mm, but with the large plug remaining. Porting (by me) is limited to opening the intake ports to +33mm, matching manifolds to that, and some relief above the valve heads (like the more-modern 750-900s have). The pistons are 88mm RAM street versions for an M750 (sold by DP once), so they have hemispherical domes, with perfect valve reliefs, that are smaller than the F1B but larger than the Pantah 650 heads. They easily fit within the chambers, which are now slightly larger because the valves are recessed some, without potential conflict. I know that a bigger piston will increase the compression ratio. I have not played with the cc measurements yet, or done any calcs, but when I get to that I can always shave a bit off the tops if too-high compression is an issue. Also, the valves are still 4.5mm apart (with the bigger valves), so the 900SS cams will not cause the valves to crash into each other. Yes, the valves are slightly shrouded, but compromises are sometimes needed to get things done. I have confidence this will be a decent engine, and a nice bike.
By the way, Carlo actually paid attention to my requests or suggestions (using a translation program to help), and even more shockingly --- just did it! He did not hide them on a shelf and make me bug him for a year and a half to do them. And he used good judgment on what really needed to be done, or not done. That is worth a lot to me now.
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