Versys head is different (more volume) for lower compression. Versys inlet and exhaust cam lobes have less duration and lift than the 650R's... Versys inlet camshaft is however identical to 650R's exhaust camshaft.
Ninja 650R/ER6:
Inlet- open 31° BTDC................Exhaust- open 50° BBDC
close 61° ABDC........................close 30° ATDC
duration 272°..........................duration 260°
cam height 36.6 +/- 0.057 mm... cam height 35.9 +/- 0.057 mm
Versys:
Inlet- open 25° BTDC................Exhaust- open 47° BBDC
close 54° ABDC........................close 25° ATDC
duration 260°..........................duration 252°
cam height 35.9 +/- 0.057 mm... cam height 35.4 +/- 0.057 mm
ECU is also mapped differently. Versys ignition timing ranges from 10° BTDC @ 1300 rpm, to 33° BTDC @ 5000+ rpm.
ER-6: From 10° BTDC @ 1300 rpm, to 35° BTDC @ 4800+ rpm.
Versys also has a crossover tube in exhaust header, before collector.
Cylinder base gasket is about 0.25 mm thick. Head gasket is a 3-layer steel, about 0.75 mm thick... You can remove the center layer of the head gasket, using copper head gasket sealer to seal the outer layers together. Such is BRP's prefered method, instead of removing base gasket, alrhough lowering the cylinder also lowers any wear ridge at top of stroke.
Gary "BRP"
http://www.blueridgeperformance.net/
"We do not use high compression pistons. JE pistons weigh more than stock. Heavier parts move slower. We run stock pistons, with a milled head and cylinder. Depending on the track, we use different combos of Versys and 650R cams. (A cheap route, is to install a Versys intake cam in your 650R, and put the 650R intake cam in the exhaust.) We have billet cams ready to grind, but until we start getting some requests, they will stay in the unground form. Proper porting & compression nets the biggest gains.
Stock rods stretch a lot faster. Not a big problem, until you start getting over 75 hp. My engine builder is currently building some flat track engines. One is a 700cc, the other 750 using stock bore/rod length, with stroked crank and custom built pistons, with pin location moved. Those should be in the 90+ hp range."