ORIGINAL: chris750
The engine that comes with the RTF version is already broken in at the factory.
Unfortunately this is a misconception that many people get about this engine. This is from the Hobbico website talking about the features of the Nexstar. [link]http://www.hobbiconexstar.com/engine.html[/link]
Based on the popular FX Series engines—famous for superior, long-lasting, low-maintenance power.
Consistently quick and easy to start.
No tuning necessary—comes factory-set for use.
Dual ball bearings offer durability and smooth operation.
Special IsoSmooth™ engine mount isolates the airframe and on-board radio gear from potentially damaging vibration.
Factory-installed needle valve limiter holds settings within the optimal range, preventing accidental over-adjustment.
What this really boils down to is that they have started the engine and adjusted the needles AT THE FACTORY. That is about all the "break in" that these engines get.
In fact, if you read the manual for the OS 46 FXi you will see that it does indeed contain instructions for breaking-in the engine. [link]http://manuals.hobbico.com/hca/hcaa17-engine-manual.pdf[/link]
The process is
as follows:
1. Install the engine with the propeller
intended for your model. Open the
needle valve to the advised starling
setting and start the engine. If the
engine stops when the glow plug
battery disconnected, open the needle
valve to the point where the engine
does not stop. Run the engine for one
minute with the throttle fully open, but
with the needle valve adjusted for rich,
slow "four-cycle" operation.
2. Now close the needle valve until the
engine speeds up to "two-cycle"
operation and allow it to run for about
10 seconds, then reopen the needlevalve
to bring the engine back to "four
cycle" operation and run it for another
10 seconds. Repeat this procedure
until the fuel tank is empty.
3. Re-start and adjust the needle-valve so
that the engine just breaks into "twocycle"
from "four-cycle" operation, then
make three or four flights, avoiding
successive "nose-up" flights.
4. During subsequent flights, the needle
valve can be gradually closed to give
more power. However, if the engine
shows signs of running too lean, the
next flight should be set rich. After a
total of ten to fifteen flights, the engine
should run continuously, on its
optimum needle-valve setting, without
loss of power as it warms up.
5. After the completion of the running-in
adjust the carburetor at optimum setting
referring to “MIXTURE CONTROL
VALVE ADJUSTMENT” section and
“SUBSEQUENT READJUSTMENT”
Ken