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Diagnostic procedures and tips

Diagnostics begins with knowing the three main properties that make an engine operate.  They are Mechanical, Electrical and Fuel.  Mechanical is compression, leakdown, cam timing, etc.  Electrical consists of all the electrical systems on a machine. Fuel is the carburetor, fuel filters and lines or any other fuel related component.

When diagnosing a machine, there is an order to follow to eliminate good components from the equation and to not overlook bad components while testing.  To properly diagnose, one must verify each of the 3 main properties is in good operating condition before moving on to the next property.  The order is…

  1. Mechanical
  2. Electrical
  3. Fuel

By systematically eliminating each property, you can be confident that you are servicing the correct component of the machine.

Tip: If there is a noticable problem over 20% throttle opening, there is a 80% chance that it is not fuel related. – Source: Genuine Honda Manual

Types of piston failures and causes

Note: Pistons may suffer from one or more of these conditions

Types of piston failures










Types of bearing failures and causes

Note: Bearings may suffer from one or more of these conditions

Types of bearing failures