Wednesday, June 2, 2010

Honda Express Spark Plug Moped NC 50 Scooter | How To Inspect

Honda Express Spark Plug inspection begins with understanding how the spark plug functions and what a GOOD running engine's moped spark plug should look like. I will also touch upon inspection, adjustment, and where to buy moped spark plug for sale.

Two cycle engines run hotter than four-cycle engines since each upward movement of the piston is a compression stroke and each downward movement, a power stroke. At the peak of the compression stroke an electrical current is sent through the spark plug and creates an electrical spark. This spark ignites the air/oil/fuel mixture thus generating the power stroke downward.

The electrical current jumps across a "gap" on the spark plug. The gap can be adjusted to the honda nc 50 manual specifications to ensure proper firing. The correct spark plug gap for the 1978 Honda Express is 0.6 - 0.7mm [see diagram below]

[click above graphic to enlarge]

You can pickup a moped spark plug gap measuring device at any local auto parts store, including Pep Boys and Advanced Auto Parts. [see picture of tool to left]

To achieve your honda moped's top speed you need to have the right combination of air and fuel in the cylinder to be ignited. This is when you will hear the terms "lean" and "rich" concerning your mixture.
  • Moped Engine Running LEAN - Too much air in fuel/air mixture being fired by the engine.
  • Moped Engine Running RICH - Too much fuel in the fuel/air mixture being fired by the engine.
To figure out if your engine is running too lean or rich you can remove and inspect your spark plug. A good running spark plug should look a light chocolate brown color. If the honda spark plug is black and sooty the engine is running too rich. If the express spark plug is black and shiny (very oily) then it is oil fouled. If the nc50 spark plug is whitish you could be running too lean, wrong ignition timing, or even too hot of a spark plug. There are spark plug charts online that can help you identify how your engine is running. [see chart to right - click to enlarge]

2 noped comments:

Linda said...

where can i purchace a nother plug

Unknown said...

What should the spark plug gap be for my 1981 Honda Express SR?

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