Page 15 - Arrow Shark 2020 RC Boats

Break-In Engine

To ensure long life and good performance from your engine, you MUST break it in properly. To obtain
the optimum fuel for your engine, mix 87 or 90 Octane regular pump gas with 100% Synthetic Quality
oil at a ratio of 16:1 (6% oil). Another choice for oil is quality marine outboard engine oil. Operate your
engine at about 1/2 to 3/4 maximum throttle opening during the break-in process. DO NOT run at full
throttle while breaking in your engine. Patience is very important here; the boat will run more slowly
during the break-in process and the engine’s output power will increase gradually over the first 3-4 tanks
of fuel. Once the engine is broken in, the power will increase substantially.

The X-30 and X-60 comes with a Arrow Shark M-39X
Pro-Mod carburetor as mentioned above, and the carb
has been pre-set at the factory. However, it may require
little adjustment to compensate for different ambient
conditions such as varying temperature, humidity,
altitude, etc. The carb has three adjustments - the low
and high speed needles and the idle screw

A: The Low-Speed Needle: The low speed
needle of the M-39x carburetor is hidden in the
center of the carburetor barrel. You need to use
a small precision flat blade screwdriver to adjust
it. When adjusting the Low-Speed Needle, apply
Loctite#222 on the needle thread in order to
hold the needle in position during operation.

The Low-Speed Needle is set at 7 turns out from
fully closed (or fully screwed in).

B: High-Speed Needle: The High-Speed Needle is set approximately
2 turns out from fully closed.

C: Idle Screw: Set this at the lowest RPM where the engine idles reliable without
stopping. Screwing the idle screw in will make your engine rev faster.

Carburetor Adjustment Tips

When adjusting the needles from their standard settings, move them only 1/8 of a turn a time. Check
the results then adjust further as needed. Never attempt to tune the high-speed needle by running the
engine at full throttle out of the water! This is very dangerous and damages the engine. The
following tips may assist in setting your M-39X Carburetor for optimum engine performance.

A: Low­Speed Needle
If the engine is easy to start, and idles a little rough (rich), and responds well when you open the throttle
with a brief show of smoke through the exhaust, then the low speed needle is close to being correct. If
the engine tends to hesitate or bog down when you open the throttle quickly (especially when the engine
is cold), or if the idle speed is too high even with the throttle barrel nearly closed, the low speed needle
is probably to lean and you need to screw it out (1/8 of a turn at a time). If the engine floods easily and is
hard to start, the low speed needle is probably set to rich and you need to screw it in slightly.

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