Inline Twin Engine Ep. 6

The last part of the crankcase assembly is the cover on the back, or the flywheel end of the engine.

First, I turned the inside of the cover where it will seat an additional ball bearing. I’ll be using a sealed ball bearing (2RS style) to serve double duty as an output shaft seal. Sealed bearings are grease filled and lubricated for the life of the bearing, but I’ll remove the inner seal and use the engine oil for lubrication, leaving the outer seal in place to prevent oil from leaking out of the engine.

Inline Twin 091 (800x450)

The part is turned over, and finished on the outside:

Inline Twin 092 (800x450)

The last operation is on the mill to drill the mounting holes:

Inline Twin 093 (800x450)

The finished part:

Inline Twin 094 (800x450)Inline Twin 095 (800x450)


The next parts for the engine are the connecting rods. The big end will house a needle roller bearing, and the small end a bronze bushing.

The first side is machined to the full depth plus a little extra to allow for the second side machining.

Inline Twin 096 (800x450)Inline Twin 097 (800x450)

A set of machinable soft jaws was milled out, to hold the rods for the second operation:

Inline Twin 098 (800x450)

The extra stock is milled off and the rods machined to final thickness.

Inline Twin 099 (800x450)

The finished connecting rods:

Inline Twin 100 (800x450)


Thank you for visiting my shop.

If you have any questions about the engine or any of the other projects, please leave a comment below, or email at yogisworkshop(at)

For other projects from the shop, please check out the Projects Page in the top menu.


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