I have been working on this engine off and on for the past year, attempting to rectify this problem. I have been on the rotax owners website with this problem, without getting enough information to help. I am using the Rotax 912 ULS Line and Heavy M/M’s to ensure the work is performed correctly. My troubleshooting skills are fairly good, this is not my first rodeo with the Rotax engines, and I have been thru the Rotax 912/914 series classes thru heavy maintenance and renewal and have worked on several Rotax 912’s. I purchased two complete carburetor overhaul kits from California Power Sports and installed them. The engine runs very similar to how it ran before I did the overhauls. I did install a new fuel pump before getting into the carbs as the removed fuel pump pressure was low at high output around 2 psi while at 6 psi at idle and midrange. All fuel lines are new, the old fuel was drained, fuel tank cleaned, fuel shutoff valve overhauled etc. I installed new carburetor choke cables from actuator to the L/R chokes. The engine runs fine from idle up to about 4900 to 5100 rpm, with smooth acceleration. At the 4900 to 5100 rpm point it begins to bog and runs slightly rough and will not accelerate smoothly again until around 5300 rpm. During the bogged down time, the throttle control stick will move approximately 4 inches of travel (1/3rd) of it’s total travel before the rpm picks up and the engine runs smoothly again up to 5500rpm. The engine throttle arms and air valve move smoothly throughout the range from idle to full open. Any thoughts? References to other resources?
Art Granger AP2115976 (435) 272-9999 Hurricane, Ut.
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