Here’s how to perform the break-in procedure correctly:
1.Decide on a fuel brand and type of blend (nitro and oil content) that you want to use.
WARNING: Whichever type of fuel that you choose, use the same fuel for break-in and everyday operation, for the life of the
engine, especially the nitro content. Here’s why: By changing fuels, chances are that either the nitro and/or oil content will
change. Different ratios of nitro and/or oil in the fuel will cause combustion chamber temperatures to change. As combustion
chamber temperatures change, the expansion rate of the piston and cylinder-sleeve will also change slightly. During the
break-in process, primarily affected is the piston and sleeve size, which “seat” (fit) together at a certain expansion rate,
determined by the normal operating temperature. Nitro and oil content in different fuels have an effect on normal operating
temperature. By changing fuels after break-in, chances are the normal operating temperatures will change. These
temperature changes will change the perfect fit (established during break-in) between the piston and sleeve, usually causing
improper and/or greater piston and sleeve clearance, causing combustion “blow-by” (loss of compression). Also, by changing
nitro and/or oil contents, all needle settings will require readjustment.
2.Start your engine following the starting procedures previously covered. During the break-in period it is much easier if
you have someone to help you, so that you can concentrate on keeping the engine running while your helper adjusts
the needles and keeps track of the temperature of the engine. A temperature gun is especially important during the
break-in period.
TUNING TIP: At any time (during and after break-in), when you first start your engine, rev the engine in quick intervals a few
times, before placing it on the ground. This helps clear out any excess fuel in the pipe, crankcase and combustion chamber
and helps get the engine warmed up quickly. It is very important to keep in mind that you should NOT fine-tune your needles
this way; this is only a quick warm-up procedure to clear the engine out and to get some quick heat into the engine. Optimal
carburetor settings will be set once the vehicle is placed on the ground and warmed up completely, following the “SETTING
THE NEEDLE VALVES FOR OPTIMUM PERFORMANCE” section further in the manual.
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