If The Engine Fails To Start; Final Adjustment - O.S. engine MAX-21RG Series Owner's Instruction Manual

IF THE ENGINE FAILS TO START

Check the following:
•
Glowplug battery discharged or glowplug defunct.
•
Fuel not reaching carburetor.
•
Engine flooded. Do not over-prime. (This could also
cause hydraulic lock and damage the engine on
application of the electric starter.)
Remove glowplug, close needle-valve and apply
starter to pump out surplus fuel. At this time cover
the plug hole with a rag so that fuel will not splash
into your eyes or mouth.
In case of the 21RG-X and
21RG(P)-X
•
In this case, turn the Mixture Control Valve
clockwise 30˚. If, on the other hand, the engine
tends to speed up momentarily and then cut out
abruptly when the throttle is opened,the idling
mixture is too lean. Correct this by turning the
Mixture Control Valve counter-clockwise 30~45˚.
NOTE:
Mixture Control Valve adjustment should be made
in steps of not more than 30~45˚, carefully
checking the effect,on throttle response, of each
small adjustment.
•
Carry out adjustments patiently, under actual
running conditions, until the engine responds
quickly and positively to the throttle control.
Warning!
Mixture adjustments (whether via the Mixture
Control Valve, or the Needle-Valve) cannot be
made accurately under 'no-load' conditions,
which, in any case, are not advised, since such
operation carries the risk of seriously damaging
the engine through over-revving and overheating.

FINAL ADJUSTMENT

•
Run the vehicle (with throttle fully open) over the
longest available straight course, in order to observe
the model's speed. Next return the car to the starting
point, close the Needle-Valve 30˚ and repeat the
run, taking note of the improvement in performance.
Continue with further runs, gradually reducing the
Needle-Valve setting and aiming to achieve the
highest straight-line speed. Remember, however,
that, if the Needle-Valve is shut down too far, the
engine will overheat and, accompanied by visibly
diminished exhaust smoke, the model will lose
speed. At this point, throttle down immediately, stop
the vehicle and reopen the Needle-Valve 30˚.
•
Having established the optimum Needle-Valve
setting, check the Mixture Control Valve setting as
follows.
•
With the engine running, close the throttle and allow
it to idle for about five seconds, then reopen the
throttle fully. If, at this point, the engine puffs out an
excessive amount of smoke and the vehicle does
not accelerate smoothly and rapidly, it is probable
that the idling mixture is too rich.
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•
With the optimum mixture control position, light
smoke is visible during high speed running,and the
engine revolutions increase smoothly during
acceleration. Remember that, if the engine is
operated with the fuel/air mixture slightly too lean, it
will overheat and run unevenly. As with all engines,
it is advisable to set both needle-valve and mixture
control screw very slightly on the rich side of the best
rpm setting, as a safety measure.
•
If the engine runs too fast with the throttle closed,
the throttle stop screw should be turned counter-
clockwise to allow the throttle opening to be
reduced.
•
Finally, beyond the nominal break-in period, a slight
readjustment toward a leaner needle setting may be
required to maintain performance.
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