Cutting Up an FXR Frame for an M8 Swap (FXR Build Ep. 2)

In Episode 2 of the FXR build series, we cut into the FXR frame, mock up the Milwaukee‑Eight engine and HHI swingarm, and sort out motor mounts, pivot blocks, and tank clearance so this thing will actually ride and handle better than stock. FXR purists might hate it, but this is what it takes to make a modern M8 powerplant work in an FXR chassis.
​

What we do:

-Cutting the FXR crossmember and dealing with frame tension.
-Mocking up the swingarm and pivot blocks for the M8 setup.
-Measuring M8 motor height and checking belt alignment and primary clearance.
-Designing bagger‑style side motor mounts so the M8 sits low without destroying the tank tunnel.
-Testing FXR tank fitment, petcock and future fuel pump clearance, and how far we can shift the M8.
-Final trimming and tacking so it all looks almost factory once welded.

Chapters:
00:00 – FXR purists crying as we cut up the frame
00:30 – Cutting and cleaning out the main crossmember
01:30 – Frame tension, battery box, and putting the frame back where it was
02:30 – Planning a lower stance and new CNC’d crossmember
03:30 – Talking pivot blocks, pivot shaft height, and swingarm fit
04:00 – Measuring engine height and checking room to drop the motor
05:00 – Dropping the Twin Cam into the FXR frame mock‑up
05:30 – Why the stock floorboard mount sucks and the plan for side motor mounts
06:00 – Converting to bagger‑style side mounts and making everything removable
06:30 – First look with the tank on: petcock and tunnel clearance
07:00 – Centering the motor and how far we can shift toward the primary side
08:00 – Tank vs. motor: what gets cut if it has to
08:30 – Belt alignment check and how close the tank really is
09:30 – 3D‑milled parts, trimming for clearance, and tacking mounts
11:00 – Test‑fitting bushings, pivot blocks, and primary angle
12:30 – Final mock‑up: pivot blocks, kickstand, and frame‑mounted parts
13:30 – Primary clearance, brake stop, and why it still looks “factory”
14:30 – Final clean‑up, small notches, and why this FXR will feel like a bagger
15:00 – Wrapping up: why an M8 FXR that confuses people is the goal

We are documenting this whole FXR build, for better or worse, so be sure to subscribe to see how it goes!