Philosophy of Mechanics


I’m not going to write a book on this.   I just want to share some simple points about mechanic work.  Some people think that what goes on inside a machine is magic.  It’s really not.  A machine is just a collection of very simple things, interacting in very simple ways.  Machines are just levers and wheels for the most part, but they also use fluids, gasses, and the the interchangeable electricity and magnetism.  The characteristics of these are all well known, some even by children.  Anybody who’s ever used a see-saw knows about levers.  Anybody who’s ridden a tricycle understands wheels.

I don’t need to know much about electricity though to understand that a spark of electricity crosses the gap of a spark plug to ignite the fuel. If that gap is closed up by carbon, I know the spark won’t work as well and I know there is something causing the carbon build up.  I also know that oil burns really dirty compared to gasoline, so obviously the motor is getting oil into where the spark plug is.  There are only three ways that can happen:  It’s in the fuel, it’s leaking past the valves, or it’s leaking past the piston rings.

Never seen the inside of a motor?  No worries.  This gets to my main point about the simplicity of mechanics:

  1. Disassemble the machine.
  2. Clean, inspect, and measure the parts.
  3. Repair or replace what’s broken or worn.
  4. Adjust the interface between parts that affect each other.
  5. Re-assemble in reverse order of the disassembly.

When I take something apart and play with it, I can see with my own eyes how one part interacts with another.  Knowing how the affect of one thing effects something else, I can see with my own eyes where the problem is.  I have shop manuals and other resources that tell me what the measurements of everything should be, so I just need to compare the specified measurements with the real measurements to find what’s out of spec.

150 main, half throttle test

This is a spark plug.  Before I took it out of the motor, I ran the motor at half throttle, under load, then hit the kill switch to stop the motor abruptly.  I can look at this one part and know from reading (and from experience) that my motor is running well.  The deposits on the electrodes are not black, meaning the carb is not tuned too rich and I’m not leaking oil into the combustion chamber.  The electrodes are not white, meaning that the carb is not tuned too lean and the heat range of the spark plug is suitable.  The electrodes are not worn away, meaning that they have plenty of life left in them.  The gap between the electrodes is in spec, meaning the spark that jumps across will be able to ignite the fuel correctly.  I do see a bit of carbon build up on the threads, meaning the spark plug was not seated firmly enough which allowed some gasses to escape.  I knew this was the case before wrenching it out, because it loosened too easily.

I don’t believe anything is actually complicated.  There are only simple things that interact in simple ways with other simple things.  The myth of complexity happens when a system has a lot of simple things to consider.

Categories: Maintenance and Tuning, Motorcycles, On My Mind

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