need a little help, i just installed a noss cool head w/ 19cc domes. now when i start the shee, it revs high. it does not rev higher and higher, it revs high and stays there. my mods are bored .040 over, pc pipes, +4 timing, elevation is about 800 ft above sea level. I pulled head back off and checked placement of all o-rings and all where in place. any thoughts as to why now i rev high?