hey so i bought a 2000 summit 700 highmark with a rebuilt engine and pretty sure a shaved head. First weekend i went to Valemount BC it ran perfect, no problems or anything. After a few days of riding around home, just out of Edmonton AB, it will run perfect and have power all the way up to 8000 rpms then bog down, i let off and pin it again and the same thing happens. i can run it from idle to 7500 constant and it doesnt bog, but when u hit 8000 it bogs? i changed plugs and same problem, any ideas?? 
