gen 2 piston, gen 1 head

After seeing the significant effort of combining a '96 Husaberg crankshaft with a KTM RFS 525 rod and piston (see my thread on Husaberg/KTM hybrid engine here: http://husaberg.org/mechanical/16703-husaberg-ktm-hybrid-engine.html), I'm now thinking about what to do with the other '96 FC600 engine that's sitting on my workbench.

What I'd like to do is send the cylinder off to be bored and sleeved to fit a 100mm piston (stock is 95mm) and have a custom rod made to connect it all together. 100mm pistons in KTM RFS engines are common and, seeing has how the KTM and Husaberg cylinders are identical save for height and the extra coolant fitting on the KTM cylinder, this shouldn't be a problem. There's even plenty of material in the engine cases for the larger sleeve.

The primary question in my mind involves the piston valve reliefs and if they'll work with the head that I intend to use (the '96 FC600 head).

I already have a KTM RFS piston working in an engine with a '96 FC600 head but that piston is .5mm below the cylinder deck at top dead center so I still don't know if there'll be an issue in an engine with the proper length rod (when using this combination of piston and head).

Cutting to the chase, does anyone know if the valve spacing and angles are the same between the gen1 ('89 to '00) engines, the gen2 ('01 to '08) engines, and the KTM RFS engines?

It would be nice to have all of the gen2 pistons, as well as 100mm KTM RFS pistons, as options for my next engine.

Hah! I love it! Bushie, I've lurked here a lot and found you to be a never-ending source of great solutions. The valve-turned-into-a-cutter is awesome! I'm a mechanical engineer by education and manufacturing engineer by trade and I was thinking of chucking a piston up in a mill and angling the mill just right to create valve notches just so...to heck with all that!

Yeah, the Wossner website is a wealth of information. I have a huge spreadsheet I've put together with various dimensions for all manner of pistons and I was eyeing the KTM 560 SMR piston but, now that I know an easier way to cut valve reliefs, I'm going to take another look for easier options.

As for dish vs flat top, I'm actually hoping for a much higher CR. I have 7 motorcycles and have resorted to filling the four strokes with race gas which has proven to last a lot longer before it plugs up those tiny FCR pilot jets. As such, this engine will be built to make the most of the race gas that will be a staple of its diet. So...flat top will be the order of the day. I'll design the custom rod to place the piston even with the top of the cylinder so the squish will be compressed head gasket thickness.