Jackal

I have a 1995 DT125R (kick start) with 2k on the clock. Dep silencer, derestricted by dealer, power valve pinned and bigger jet, standard sprockets. Very fast bike for 125cc. 80mph @ 9000rpm. Flys after 6500rpm but nothing below, so i got a servo motor etc. I have fitted the parts following DT125.net etc. Went for a test ride, power from 4500rpm but it has lost it's top end. Slows at 7000rpm onwards. Anyone had this problem or any ideas?