58 Tiger Cub Motorcycle

FRS 106, Michael Littman – Spring 2017

March 16, 2017 (Thursday, Week 6)


  • Updates on shop progress

  • Readings and discussion of references and content

Updates- NOTE: Tuesday’s shop session was shortened because of the snow day and lack of helpers

  • Bottom End: Investigated the chain rubbing on the inner primary engine cover and the associated oil leaks/structural faults

  • Clutch: Installed hose clamps on oil lines and hoses on the blue bike; prepared the blue bike to drain oil in preparation to take off oil pump

  • Electrical: Continued fixing the ignition switch

  • Fasteners : Worked on installing the Japanese (turns out to be Chinese) carb on the blue bike; didn’t quite fit as the spring was too long and the air filter also was too tight

  • Forks: Worked on finding ways to get forks ready for powder coater using triple trees

  • Frame: Tried to find nuts and clean threads using tap and die

  • Top End: Cleaned up new oil line and cleaned barrel fins

  • Wheels: Disassembled rear brake assembly

Calculations Lesson:

Recapped last time’s questions:

  • How fast can a motorcycle go? Used RPM and gear ratios to determine top speed.

  • How much is maximum torque in rear wheel? Used friction force and diameter of the wheel to determine 200 ft-lbs of torque.

Building on these, we can ask how much tension the chain would be able to bear. We can determine this using the torque of the engine and the radius of the sprocket. The top of the chain bears the force whereas the bottom does not (at least when the engine is accelerating). When the engine is being used for engine braking, the tension shifts to the lower leg of the chain.

We can also ask what the engine torque is. Using the equation power= (torque [in ft-lbs])x(angular velocity [in rad/sec]) we can work backwards to determine what the engine torque is.

The final question we addressed was how much horsepower do we need? Drew out the incline plane diagram to illustrate what the power requirement would be to maintain velocity uphill. Used the power equation P=Force [lbs] x Velocity [ft/min] to determine what the power requirements will be.


Zen and the Art of Motorcycle Maintenance, Chapter 15

  • No substantial motorcycle references

  • Chapter focuses on his return to the campus he used to teach at

  • References the seed crystal of his memory about Quality- becomes an obsessive passion

    • Quality will become the focus of the rest of the book- there becomes a romantic and a classical divide in the ideas

    • There is a mention of the “you know it when you see it” attitude towards quality

Shop Class as Soulcraft, pages 93-113

  • Motorcycle References:

    • Discussion of wheel bearing and toying around with the bearing while drying it

    • Starter motor and the bearing in it being shot when the spinning cylinder’s bearings open up and rattle around, causing motor failure

    • Galling of the cam lobes because the valve springs are too tight- done by testing the force of the springs against a bathroom scale. Someone had installed a modified valve springs that had been installed to allow the engine to go to a higher engine RPM

    • References to Zen with the “idiocy” story of the mechanics

    • Oil galleries- reference to Pirsig- that caused seizures in head. Prof. Littman showed demonstration with the brake cam’s grease gallery

  • Content:

    • Discusses how he got into motorcycle maintenance in Chicago

    • Compares his experience in academia and at the think tank to his time working on motorcycles

  • Differentiates between liberal arts and servile arts- but he did not feel free working in the liberal arts (think tank/university)

  • Faces dilemma of being a sole practitioner and running a shop

  • Defines idiocy as both an ethical and practical failure