OZ,
Just curious, the pipe is a 91 honda, how did you get around the water pipe from the cylinder to the pump? I've completed 2 perimeter framed 500's using a 02 KX 250 chassis and bought a honda pipe but the clearance wasn't there, I would have had to dent the pipe in around the water hose to get it to fit. Ultimately I bought a PC KX500 pipe cut, twisted and rewelded it, It works great but takes about 6-7 hours to fit it. I'm thinking that I used the wrong year Honda pipe. Did you try to keep the headpipe length the same as the KX. and lastly how does it work?
Thanks