912UL Issues

[kmach]

Hi, To me it sounds like your sync might be out. some Rotax people sync at 2500, some recommend and swear by doing it at 3000-3500 rpm. I have tried both and around 3000 works best for my setup .

I recall my first syncs didn't work out and I have had the fuel exiting the carb overflow. retried the sync , with some trial and error and experience syncing is easy and definitely smooths idle and lower rpms out.

[jamesmil]

hi guys, saw this a while back on a friends 912. syncsed the carbs, no help. rebuilt carbs, no help. installed new carbs, no help. after all that time and money it still ran so bad at low speed that we took the prop off so we could pull plug wires off while it was running to try and find the problem and lo and behold it ran great.
called lockwood and told them what we were seeing and they said to send them the gear box to be checked out. turns out the dog gear was frozen to the shaft and was not cushioning the low rpm impulses from the motor as it was supposed to. much money later and a rebuilt drive it runs great. hope this helps

[68niou1]

Jim Scott (Aircore Aviation) when I called him said the exact same thing. So I am pulling the gearbox and shipping it off. I will keep everyone updated.

Thanks for all the input-

Scott

[SkyPirate]

this is also a common low rpm thing with the B box's on a 582 but its the spacers and springs on output shaft that is the culprit,..when you start getting allot of low rpm chatter out of the gear box,..time for rebuild

[68niou1]

I thought I would post the end result on this so maybe it might help someone else along the line later on- It turned out to be the gearbox, sent it out to Jim Scott at Aircore Aviation in Arlington, (great guy and highly recommended) got it back in record time(would have been faster but parts were back ordered) bolted it back up, retorqued everything, safety wired, fired up and she runs smooooth. no puking carb, no weird noises. And my plane only has 145 hours on it- so go figure.

[Av8r3400]

I have the parts in hand to do mine now too. I hope it works as well.

As a side note, what prop do you have? I have a 3-blade 68" warp with tapered nickel leading edges. 450 hours tt on the motor.

[Slyfox]

fantastic. when i left the airport last night I saw you going out the gate with your airplane in tow. I take it you went up to deer park with it. did you get a chance to fly it yet. I know a few years ago they complained of a rough engine and it kept the airplane from flying. glad you found the problem. what parts did they change out, very curious.

[68niou1]

I have the parts in hand to do mine now too. I hope it works as well.

As a side note, what prop do you have? I have a 3-blade 68" warp with tapered nickel leading edges. 450 hours tt on the motor.

I will check it out and let you know- I have no idea other than it is a warp 3 blade non nickel leading edge. I know it pulls 5200 on climb out so I think its set about perfect from what limited knowledge I have gained-