We recommend Byron's fuel at 20%
nitro content to run-in (break-in) the engine. The
best way to break-in the engine is to follow the
steps below:
Step 1. The first few runs of your new engine
are critical. Once your engine starts, place the
car on a stand so that its wheels can't touch
the ground. Let the engine idle at low rpm for
a few minutes (two or three minutes will do),
then shut the engine down and let it cool. During
this procedure, it's also important that the piston
not be at the top of the cylinder while the engine
is cooling. Part of what's taking place during
break-in is that the engine's mating parts are
being heat-cycled, which means they are expanding
when the engine is hot and contracting when it
cools. Heat cycling stabilizes the metal and allows
mating parts to fit better against each other.
Keeping the piston out of the upper portion of
the cylinder (which is smaller in diameter than
the lower portion in order to create a better
seal during combustion) will allow the cylinder
to properly contract as it cools-without interference
from the piston. To figure out where the piston
is in relation to the cylinder, just turn the
flywheel-it will become difficult to turn when
the piston is at the top of the cylinder, where
the fit between the piston and cylinder is its
tightest. Just turn the flywheel until the piston
is in the middle of its "easy turning" part. Repeat
the above steps three or four more times.
Step 2. After you've heat-cycled your engine,
you can finally put it on the track. But don't
get too excited yet - you must run it with a very
rich high-speed needle setting. Lots of blue smoke
should be coming from the exhaust, and the engine
should sound "blubbery." During this procedure,
it's vital that you avoid prolonged use of full
throttle, which could strain the engine. You should
instead "blip" the throttle as you drive the car
to avoid spending too much time in one particular
rpm range. Run the engine using these settings
for three or four tankful's of fuel, allowing
the engine to cool in between runs.
Step 3. Once you've put about six to eight tanks
of fuel through the engine (as outlined above),
it's time to begin leaning the high-speed needle
and making some power! Begin by leaning the high-speed
needle (by turning it inward, or clockwise) by
about one-hour (if you imagine the needle as a
clock face, one full turn of the needle would
equal 12 hours). Run the car for a minute or so,
then bring it back in and lean the needle by another
one hour increment. Repeat this process until
the engine begins to achieve good rpm, but it
shouldn't be allowed to "scream" quite yet. The
engine should still be creating lots of blue smoke
from its exhaust. Before you achieve that screaming
race setting, we recommend that you run your engine
for a few more tankful's in this "almost race"
setting. Once you get the needle set to where
your engine is making good rpm, richen it (by
turning the needle counter-clockwise) by about
a quarter of a turn-this is your final setting.
Step 4. Once you've found a good setting for
the high-speed needle that allows the engine to
make good power yet still push plenty of blue
smoke from the exhaust (especially when the car
exits a turn), it's time to set the low-end needle
and the idle-stop screw. For now, set the idle-stop
screw so that the engine will idle at a moderate
rpm without stalling. Bring the engine up to operating
temperature by driving it for a few minutes. Now
stop the car and listen to the engine's idle speed.
If the engine idles fast but then slows down in
just a few seconds, the low-speed needle is probably
set too rich. Lean the low-speed needle (by turning
it clockwise in one-hour increments) until, after
running a few more laps, the idle stays high for
about twenty seconds or so when you stop the car.
Once you've done this, use the idle-stop screw
to make the final adjustment of the idle speed.
Setting your engine's idle speed isn't a contest
to see how low you can get it without stalling
the engine! Your goal when setting the idle should
be to allow the engine to run at moderate rpm
without the clutch being engauged whatsoever.
Your car should be able to sit at a standstill
when idling. If you have to hold the brake, the
idle is too high. If you have to blip the throttle
to prevent stalling the engine, the idle it too
low. Afterthought: Nitro powered R/C vehicles
can be tons of fun, or they can cause tons of
frustration. The difference between success or
failure lies with the break-in process. If you
follow these steps, have patience, and use your
noggin, you're assured of success. Rushing through
the break-in procedure or worse, forgetting it
altogether, is a recipe for disaster. Tuning your
engine is the hardest part of nitro racing. But
once you've learned how the carburetor works,
and which screw does what, it will all become
second nature. So when you're running your car,
you'll always know exactly what to adjust to gain
the highest level of performance possible.
