Rotax 503 Rough Idle?
Tom Epley
I have a new Rotax 503 single carb which is experiencing rough idle
when pulled back to the idle stop. The carb is adjusted to 220 rpm.
The idle usually settles to 2200 but when warm sometimes drops to 1400
rpm. It will then idle very roughly and over about 30 seconds recover
to 2200 rpm. Suggestions?
Peter Leaver
Gidday Tom,
I had the same problem with my dual carb Rotax 503 after working in the
carbs, replacing mounts, one needle, etc.
It turned out that the needles were too lean. I raised them one notch and
everything came back to normal. Idle smooth and back up to about 2000 rpm
from the 1600 it had been coughing at.
While I was on a local flight at around 700 feet I opened the throttle to
full, to go into a climb, the engine started to cough and splutter, but
settled back again when I reduced the power. Tried it again, and no way did
it want to run about 5500 rpm. Obviously not enough fuel there.
Occasionally on full application of power for take-off the engine sagged
for a second and then all came right. Guess I was lucky not to end up off
the end of the runway.
It may pay perhaps to check your jets and needles for any sign of
contamination which may also be restricting the fuel flow.
Good muck Tom,
Pete.
Peter Leaver
Tauranga, New Zealand
pe...@enternet.co.nz
William Everett
Don't overlook the fact that a lean condition doesn't just mean "not
enough fuel", but also "too much air". Your carb might be fine as now
set, but will respond as though too lean should any excess air be
introduced into the intake passage. Worth checking out.
A piece or two of tiny "crud" or even water, in the float can reek havoc
with the idle (and other speed ranges, too), so be positive the whole fuel
system, along with the carb, are clean.
Of course we're filtering every ounce of fuel as it's poured into the
plane, right? Yeah, I knew we were.
--
Bill Everett
P.O.Box 60038 St. Pete, FL 33784-0038
sfz...@scfn.thpl.lib.fl.us
or try: beve...@juno.com
ted ooms
Tom Epley wrote:
>
> I have a new Rotax 503 single carb which is experiencing rough idle
> when pulled back to the idle stop. The carb is adjusted to 220 rpm.
> The idle usually settles to 2200 but when warm sometimes drops to 1400
> rpm. It will then idle very roughly and over about 30 seconds recover
idle,all I have to do is blow out my spraynozzle in the carburator and
wala problem solved. Ted
Tom Epley
tom....@utmb.edu (Tom Epley) wrote:
>I have a new Rotax 503 single carb which is experiencing rough idle
>when pulled back to the idle stop. The carb is adjusted to 220 rpm.
>The idle usually settles to 2200 but when warm sometimes drops to 1400
>rpm. It will then idle very roughly and over about 30 seconds recover
>to 2200 rpm. Suggestions?
Thanks all...it's fixed...several prolbems..small amount of blockage
in idle jet . Cleaned and improved but not fixed.
Put in new plugs gapped at .016 instead of .018 and reset fuel level
in bowel correctly (without floats at 1/2". Set idle at 2200 rpm and
no further problems.
tom epley