Hi all,

I am a newbie on this forum. I have a mc18 and 2 mc21 track bikes. The mc 18 is an absolute stonker. One of my mc21 has problems at high rpm(8500-10,000). It has a HRC jet kit and runs open carbs. I have spent four days at the track playing with the jetting but cannot get the top quarter throttle/ high rpm to run properly. I have been up and down the main jets and used A,B and C needles but no joy. Low and mid are nice. I had a slight air leak around one exhaust gasket and fitted new gaskets but it made no difference. It has the wire splices done. (the other mc21 has the proper HRC wiring kit) Has anyone got an idea of where to look? Has anyone else had a similar problem and have any wisdom to impart? Should I be looking at the wiring, power valves or what?