First post on this forum so...dont hurt me. Concerning the 2 valve GS1100 engine stuff..you might want to look at the later model GPZ Kawasaki pistons with *i think* the 18mm wristpins(1983 and 1984 models had a 18mm wristpin.The stroke is the same on the Kawasaki as the Suzuki. Not sure about the valve angles and deck heights but i bet its close. Most of the older 2 valves would take cams up to around .420 lift..with the shim on top standard setup. Beyond that youre now talking about shorter valve guides,a shim under bucket set up with better springs. Also,you have to be mindful of the clearance between the cam lobe and the cylinder head,we used to have to not only clearance the valve cover so the lobe didnt hit it,but also modify where the lobe begins to contact the shim. I cant remember exactly but i think the 1100 2 valve had the bigger intake manifolds? You might could use the larger Kawasaki ones and slap some bigger carbs on..(like 34 flatslides)..on your cylinder head,theres a fair amount of gain just by doing some bowl work around the seats,and cleaning up around the valve guide. Not talkin full out port job..just gains. As far as valves go...you can get stainless valves in all the sizes,blank keeper grooves,and have the grooves cut into them if you decided to go the bigger valve route. Again..i would try to get my hands on a GPZ Kawasaki valve and compare the stem lengths and keeper groove location,and the stem height. Most of these old bikes wake up a good bit with more compression,but its hard on the starter set up,the starter rotor has the starter clutch built onto the back of it,and after you raise compression and all the other stuff,if the battery is weak and you go to start it and it doesnt spin fast enough,and kicks back,it can spin the rotor loose and or tear up the starter clutch..neither is good,the rotor is a tapered fit theres no keyway or key and it will tear the crap out of the end of the crankshaft that it rides on. If your guy really wants to go fast i can tell ya he is going to have to stay on top of the maintenance end..sometimes we end up opening the ole can of worms. They do make a heavy duty clutch backing plate set up(with heavier damping springs and a thicker plate that holds them in place) for the 4 valve stuff,i think that the clutch hubs are similar if not the same. The crankshaft is all pressed together and welding the pins to keep it from twisting was the norm. Not sure on the availability of heavier cylinder studs,,you could always mix and match from 4 valve stuff,if you measured the stud lengths and called APE they might could hook you up They may even have some 2 valve piston kits,,maybe. Worth a call anyway those dudes are some pretty clever cookies and Jay Eshback knows his stuff on these old engines. Ok hope this helps...
