I have a customer with a 912ULS powered powered parachute. There is a dead band/no increase in engine rpm from 4500 to 4800 as the throttle lever is travels 2.5 inches (no change in rpm) mid range in throttle travel, then after the 2.5 inches of throttle travel, the RPM resumes smoothy from 4500 thru 4800 and on up to max at 5800. Carbs have been sync'd twice, both carbs have been removed, cleaned, inspected and reassembled with new gaskets. The main jet needle circlip has be reset from #1 position to #3 position with no effect on the dead band. Carbs were reassembled, reinstalled and sync'd again. Both throttle arms moved smoothly from idle to full on position with no mechanial discrepanies or sticking when moved with the e throttle push/pull control input. Both vents are clear. A new fuel pump was installed along with new fuel lines, fuel pump pressure was checked throughout the rpm range, no defects noted. Any help/advice appreciated, Art
