Hello
Mentioned on this thread is the fact that a CB450/500 is very expensive to make fast. Due to the very 1960's cylinder head design you have to run a very high dome on piston to get compression, added to that one must deal with the very steep valve angle. 500 head is exactly the same in all respects as the 450 head, save for it has ordinary valve seats vs the 450 which has a "skull" type iron/steel dome sunk into the head. 500 head is the best to use.
Right now would be the time to get yourself a CB350 Honda twin and go that way, as you will be spending 3X's money to get almost the same performance with 450/500 twin.
I did the work up with KPMI to make the 5mm valve spring conversion kit. Not anyone from Team Hansen had anything to do with that. Very nice kit, but not worth doing unless you remake (ie: machine cams for adjustable sprockets) both cams and go to 2 spark plugs per cylinder.
Next you will need to machine head for two spark plugs per cylinder to sped up flame path travel time for your ignition will per 45-50 BTDC!
Pistons larger than 72mm will need liners machined and installed as standard liners will distort and cause ring sealing problems.
You must move ignition from camshaft end to end of crank or your timing will vary enough, due to cam chain length/stretch enough to cause problems. This relocation makes the bike race-only...no street use, as you can run no AC generator.
A better oiling system is also a good idea and out friend in Italy is the way to go in that department.
Also, if you are to run in top of class, must have Nova 5 speed (if you can find one) or newer 6 speed close ratio gear box.
I can build you a complete engine ready to run at front or could you consider another bike for this class? I also can supply all parts/services you will need for this effort.
KOS
http://www.m3racing.comPS Our CR450 replica was 3rd at Daytona 1999, after leading the race and ended up just back of Franco Bonnera on Factory MV and Todd Henning on CB450.
1998 3rd overall in AHRMA National Championship
1999 2nd overall in AHRMA National Championship