20 February 2018 – 63 Tiger Cub Motorcycle

February 20, 2018

Notes by Noelle Goudy

Assignment due Thursday, February 22:

“combustion-chemistry.pdf”
“Tiger-Cub-Engine-Calculations-revised.pdf”

This week:

Starting to study the science part of the book
Seeing how fast the motorcycle can run
Looking at data sheets and octane ratings
Thursday: learning about combustion
Next week: learning about aerodynamics and drag on Tuesday

Housekeeping:

Emily: With Jordan, cleaned up and polished the engine covers using a sandblaster, sandpaper, and a die grinder
- A die grinder uses compressed air to make a fan blow with very high speed (and low torque) – great for polishing
Noelle: With Alex, disassembled the Amal carburetor and found and labeled all parts for it
David: Cleaned the pieces of the transmission with Alex
Jake: Made a tool to compress the shocks; took the shocks apart and cleaned them
Brendan: Had to bore a hole to take apart the shocks; sandblasted them
Connor: General disassembly; removed oil pump; missing ball bearing for the oil pump
- Note to quartermasters: make sure to order new ball bearing
Eric: With Hannah, sandblasted different parts of the wheel; going to assemble motorcycle stands today in shop
Alex: With Noelle, worked on disassembling the carburetor and cataloged parts; began to clean the carburetor
Alex: Finishing disassembling bottom half of engine; took of main sprocket
Grace: Worked with Connor and Alex to disassemble the engine; will check to make sure everything is working; will go through the gasket packet to figure out if replacements are needed
Jordan: Worked on polishing with the polishing wheel and by hand
Sarah: With Ricky tested connections with a voltmeter and with a light; today, will generate sparks with old motorcycle
Julianne: Continued to clean top end parts; need a piston and rings
Ricky: With Sarah, checked electrical connections
Charlie: Sandblasted the two top end pieces
Hannah is not here

Discussion of Chapters 9 and 10:

Chapter 9:
- Motorcycle References
  - Engine misfire:
    - Spark fires but no fuel is ignited
    - Misfire can cause a bang or backfire
    - Happens if the unexploded gas goes into the exhaust line
- Content
  - Scientific Method
    - Helpful to diagnose complicated problems
    - Ends up driving Phaedrus crazy
    - Six elements:
      - Statement of problem
      - Hypotheses
      - Experiments for each hypothesis
      - Predicted results of the experiment
      - Observed results
      - Conclusions
    - Hypotheses sometimes sound dumb but are important because assumptions shouldn’t be made
    - 132: Experiment only fails if it cannot provide data either way
  - Inductive vs. Deductive reasoning
    - Inductive: making a hypothesis out of data
    - Deductive reasoning: inferring what is happening based on observations
  - Underlying Form
  - Classic vs. Romantic approach
Chapter 10:
- Content
  - Characterizing Phaedrus: how did he lose his mind? Comparing Phaedrus and Einstein
    - Both study science for the stake of science – to learn – pursuit of knowledge
    - Page 111: The difference between experience and nature
      - Does nature provide the data?
    - Phaedrus is more interested in inquiry
      - The philosopher’s approach
      - Where knowledge comes from
    - Phaedrus thinks that there are infinite hypotheses and thus thinks that they can never be solved
    - Exponential growth of data and information but not of knowledge

Top Speed of the Motorcycle: 62 mph

K’Nex model of a Model T engine: Four stroke cycle
- 2:1 gear ratio
- Crack turns the connecting rod, which makes the pistons move up and down
- The spark plug goes off when the piston is at the top
- As the piston move up, the exhaust is blown out
- Intake valve opens when the piston is at the bottom: air and fuel mixture enters
- RPM: revolutions per minute of the crank
- What is the maximum RPM of our motorcycle?
“Triumph-10001.pdf” – workshop instruction manual
- We have the T20 model
- Technical data is located at the bottom of the manual:
  - 63 mm bore (diameter of piston)
  - 64 mm stroke
  - Power output: 10 (brake) horsepower at 6000 RPM
    - 6000 rpm = 100 revolutions per second
  - Gear ratios
    - Engine sprocket: 19 (teeth)
    - Clutch sprocket: 48 (teeth)
    - Gearbox sprocket: 17 (teeth)
    - Rear wheel sprocket: 46 (teeth)
- Clutch is going at 2375 RPM
  - Crack to clutch: 19/46 * 6000 = 2375 RPM
- Rear wheel is going at 877 RPM (in the fourth gear)
  - Clutch to rear wheel in top gear: 17/46 * 2375 = 877 RPM = 14.6 revolutions per second
  - 14.6 revolutions per second * 6.28 ft = 91.7 feet per second
  - 91.7/66 = 1.04 * 60 mph = 62 mph
- 48/19 * 46/17 = 6.84 (which was given as the top gear ratio)
  - Ratio of how fast the crank is turning to how fast the wheel is turning
  - Gear ratios increase as the gear goes down
Tiger Cub Bible
- Page 173: Gearboxes for all of the Tiger Cub motorcycles
  - Standard, wide, close, extra-close, and ultra-close gearboxes
    - We have the standard model