Wednesday, December 15, 2010

Bing Carb Needle/O Ring #74

Bing Carb Needle/O Ring
My Rotax 447 was starting really badly. An inspector could only find a worn needle and advised me to buy a new needle, circlip and O-ring, after which it started first or second pull every time.....wonderful. Take off was uneventful and a full power climb to altitude 2000 feet ensued. As it was such a nice evening I decided to climb further this time a cruise climb and that's when the problem started. Vibration and then some, thinking 'carb icing' I gave it full power to clear its throat and away it went smoothly to 3000 feet; back to 4500 revs and more vibration. The mighty Rotax was smooth at full power, but rough at anything else so returned to base. Next  day it again stuttered and baulked at 5000 rpm every time. I went home a sorry and beaten man, searched the net and found that new needles with clip and o-ring should only be fitted with a new spring cap with a recess built in for the o-ring !
I took out the o-ring and it was back to its purring self. Conair sell the o-ring only with the spring cap.


P.S.
When re-assembling the slide make sure it is not installed on top of the white plastic piece. It should be under the plastic piece.

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