BREAK-IN
F
or a new engine, a fuel with low nitro rating and high oil content is highly recommended for the first 10
tanks (125cc per tank). Although one can use a fuel with nitro and oil rating combination stated within
the recommended guidelines, 5% nitro and 25% oil is best during break-in period. Please carefully follow
the procedures below for a proper break-in, first 10 tanks of fuel:
1. Check the carburetor's high speed needle. With a fresh new engine, fully close the high speed needle,
then open it 3 turns from fully closed.
2. Check the carburetor's idle setting. Set the idle screw so that the carburetor has 2mm opening when
the throttle is closed.
3. Follow the procedure for starting the engine.
4. Once the engine is started, run the car in an open, flat area. Try to vary throttle positions and operate
with smooth throttle transitions. Keep in mind that the new engine should be run at mostly low to mid
throttle with very little time at full throttle (no more than 1 second).
5. Set the carburetor to break-in setting accordingly.
If the engine stalls at low RPM, then set the low speed mixture leaner by turning in (clock
wise) the low speed needle 1/8 turn. It is normal for engines to stall during the first
10 tanks of fuel because break-in setting is always rich.
If the engine stalls at full throttle (no more than 1 second), then set the high speed mixture
leaner by turning in (clockwise) the high speed needle 1/8 turn.
If the engine races at full throttle (no more than 1 second), then set the high speed mixture
richer by turning out (counterclockwise) the high speed needle 1/8 turn.
6. The engine should be set as rich as possible before it stalls at full throttle (no more than 1 second).
To do this, turn the high speed needle out (counterclockwise) 1/8 turn at a time until the engine stalls.
Then, turn this needle back 1/8 turn clockwise, and follow STEP #3 and #4 for the next 2 tanks of fuel.
7. On the 3rd tank of fuel, set the high speed mixture leaner by turning in (clockwise) the high speed
needle 1/8 turn. Repeat STEP #4.
8. On the 6TH tank of fuel, set the high speed mixture leaner by turning in (clockwise) the high speed
needle 1/8 turn. Repeat STEP #4.
9. Finish the break-in process by running 3 more thanks of fuel and repeating STEP #4.
10. After the 10th tank, the engine should be properly broken-in and ready for normal use. Follow the
engine tuning procedure to set up the engine carburetor for normal use.
ENGINE TUNING
The included PRO-70BX engine is a ring engine, and as such, it will need to be tuned differently than a
regular ABC engine. The ring on the piston requires lubrication for proper function. To achieve proper
lubrication, the engine needs to be run with high oil content fuel and at rich carburetor setting.
After proper break-in, the new engine is ready for regular operations. For normal use, please use the
recommended fuel formula described in the fuel section, and follow the procedures below to achieve
proper carburetor setting. Clockwise needle turn will provide leaner setting (lower fuel to air mixture),
and counterclockwise needle turn will provide richer setting (higher fuel to air mixture). Do not perform
this procedure until the engine has been properly broken in:
1. Check the carburetor's idle setting. Set the idle screw (small screw with spring off center on the side
of carburetor body) so that the carburetor has 2mm opening when the throttle is closed.
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Summary of Contents for EK4-S2
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