Xray NT18 0.8cc Instruction And Safety Manual - page 20
20
• The engine’s compression may be low due to wear. This will make the engine difficult to start when it is warm, and may
tend to stall when running and when the throttle is closed suddenly.
Engine will not spin (starter box will not turn the engine):
• The engine may be flooded and hydraulically locked. Refer to section "Flooding & Hydraulic Lockup".
• Check for binding at the engine flywheel. If you are not able to turn the engine by hand, the engine could be flooded,
there could be binding in the clutch system, the piston may be stuck at the top of the cylinder (TDC), or there could be
internal engine damage. (Note: During engine break-in, it is normal for the engine to be extremely tight and hard to
turn when the piston reaches the top of the cylinder.)
Engine is very sluggish, hard to start, and will not idle during initial break in:
• The factory default break-in settings (on the carburetor) may be too rich for your location, weather conditions, or fuel
brand. Extremes in temperature, humidity, barometric pressure, and altitude cannot always be accounted for by the
factory default settings. These symptoms may occur when air density is very low (such as in high mountains or extremely
cold temperatures. Under these conditions, lean the main needle valve slightly (1/8 turn CW), and check if there is any
improvement in starting and idling. Only lean the main needle until the engine runs and idles reliably, then continue the
break-in process.
• Different fuel brands/types – in combination with extreme weather conditions – can also make the factory default break-
in settings too rich and cause these symptoms. Try leaning the fuel mixture slightly (1/8 turn CW), and check if there is
any improvement in starting and idling.
Engine performance is sluggish:
• Engine performance depends on the carb settings and how they compensate for the weather & atmospheric conditions.
Before suspecting other issues, richen the main needle by at least 1/4 turn CCW, then retune the engine.
• Try installing a new glowplug.
• If carb settings are proper, ensure the fuel is fresh. Old fuel, or fuel that has been left uncapped for a long period, may
cause sluggish performance.
• Verify that there is no drivetrain binding.