Cutting the Sportster cases with the Sawzall of Death was the easy part, crude cuts and wanton amputation doesn’t take much skill to master. The next part to figure out were the motor mounts—probably the most important bit of custom work for the entire project and far more precise (relatively speaking). No pressure though…

As I mentioned in Part 1 of this build, I had to get my hands on a number of parts and assemble them first in order to get an idea of where the motor would need to be mounted in the frame. The rear wheel had to be positioned in the frame; the chain had to align with the trans and the transmission’s location would dictate where the motor needed to be. I was lucky — and able to position the centerline of the 200mm Metzeler rear tire just a hair off the center of the backbone of the frame. A 7/8- inch wide sprocket spacer, a relatively narrow double roller RK chain, and a 9/10-inch offset sprocket mounted on the BAKER Franken-tranny all combined to make this custom driveline a bolt together affair from the transmission to the rear wheel.

The motor mounts for my Sportster motor in my Xtreme Cycle Designs big-twin frame were the exact opposite of bolt- on. First, I placed an assortment of thin plywood pieces under the motor’s cases, and once I squared it up within the frame, I clamped the motor to the frame using the remaining rear section of the transmission case, so I could fabricate the mounts. I’m OK at welding steel, but horrible when using aluminum, so I chose to make the front mounts because I knew I could make them from plate steel I already had in my garage. I’d take my project to an expert welder for the aluminum rear mount.

When I was happy with the alignment of the motor and transmission I cut out a cardboard template for side plates that would bolt to the original Sportster mount holes on the cases.

I made sure the templates fit nice and tight before tracing their shapes onto a piece of an eighth-inch plate steel.

Plasma cutters are faster than a cutting wheel when cutting curved shapes and they make less mess—but you still have to grind down the rough edges and smooth everything out before using the part.

Once the front mounts were cut out and sanded, I figured out where to punch the bolt holes by holding the plates up to the motor and the frame and marked the two spots on each mount.

In the middle of each marked circle I found the center point and used a center punch to mark the center of the intended hole and to prevent my drill from wandering outside of the marked area as I drilled the mounting holes.

I used my drill press to create all four mounting holes.

The mounts were attached to the cases, and I used another piece of plate steel to make the section of the mounts that would bolt to the frame.

I placed the frame mounting section underneath the motor-case mount half and tacked it together in the frame.

Then I removed the entire mount assembly and finished welding it together with my HTP America TiG welder.

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