Thank you very much for all suggestions received on how to solve the
problems I experienced.
The =93rough on one magnet=94 is now resolved, and the rough start of
cold
engine almost gone (maybe I have become paranoid and forgotten that
912ULS
always starts a little =93hard=94).
I replaced the battery with identical one ' Leoch 28 Ah. The first
cold
start (with choke) was a little rough. I let the engine run some 20
seconds
and stopped it. Restarted again with choke ' now much less roughness.
I did several stops and restarts. When the oil temp reached the
mid-30s,
smooth starts.
Carb sync solved the second problem ' some roughness on one magnet at
4 000
rpm, smooth on the other, rpm diff some 50 rpm: At 4 000 rpm the carbs
where out of sync by 1.5 cm HG ( a good =BD inch). Carb sync at this
rpm made
the roughness on one magnet go away. Rpm drop on either magnet abt 180
rpm,
rpm diff + - 0.
Before I started the engine, I pressure checked that the float valves
closed, and I inspected the carb bowls (clean). With engine on idle, I
bent, pushed and pulled on the wires to and from the electronic modules
on
top of the engine. No indication of broken or intermittent contact.
The positive effect of new battery was to be expected. The carb sync
was
suggested by the Scandinavian Rotax agent, but I must admit that I was a
little skeptical. He explained it by pointing to how the spark plugs
are
connected to the magnets on 912: Magnet A: cyl 1-2 top, cyl 3-4
bottom.
Magnet B: cyl 1-2 bottom, cyl 3-4 top (#1 is right forward, 2 left
forward,
3 right aft, 4 left aft). ) 914 has all 4 tops on one magnet, all 4
bottoms on the other. I still cannot explain why carb sync should
matter
during mag check, but it certainly does.
Regards,
Svein
LN-SKJ
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