Hi all,
We have a Europa XS with Rotax 912S that has been flying about 400
hours. During our annual inspections we have been taking the cylinder
compressions using an automotive compression tester. The first two
inpections found the compression to be about 180 psi per cylinder.
during the last inspection (about 10 months ago) the compression
readings went up about 15-20 psi. At the time we thought this was
probably the fault of the compression gauge, but now wonder if it might
instead be real.
We have had more difficult starting this past year or two than
when the plane/engine were new. We have changed plugs, balanced carbs,
dissasmbled and cleaned the carbs, and installed a new battery, all to
no avail. I wonder if it could be the increased compression causing
starting problems. Also, aren't you more likely to get detonation as
the compression goes up?
If/when carbon and/or lead deposits build up on the head and
pistons, the compression will go up. We have heard back yard mechanic
stories about pouring water or ATF (automatic trans fluid) down the carb
while the engine is running to clear the deposits out. An auto mechanic
friend says higher compression from carbon deposits can make a car fail
a smog test (nitrous oxide emissions), and is fixed by filling the
cylinders with a special cleaner overnight, then running some more thru
the carb the next day.
Has anyone seen their Rotax compression go up?
If so, did it start harder, and what did you do to fix it?
regards,
Terry Seaver
A135 / N135TD
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