The Excelsior Project, 39: Fixing Bearings

Exhaust nuts, manually machined from aluminum bronze. Nice to machine.

Intake nuts, manually machined from 303 stainless.Quite a bit of work.

Fully machined heads, finally. Sparkplug threads are 18mm. Included valve angle is 52 degrees.

Did I mention there was a bearing problem? I had chosen straight roller bearings for the sprocket side, and never realized the outer race had been designed to have a "size-on-size" press fit, which doesn't work in an alloy case that expands when the engine gets hot. Here I'm boring out the case to get less of a press fit, but I also have to hone out the outer races to make this system work.

The engine sprocket has six tapped 5mm holes.

I can bolt on a hub with a 3/4" drive for the electric starter. A black delrin "nose" will hide the allen screw heads.

Or, bolt on a degree wheel to setup cam or ignition timing.


Flashback Fabrications Inc.tel 604-888-8785email
PO Box 401Lynden WA98264

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