New Power For That Old FXR
Article And Photos By: Keith Cole
Originally Published In The March 2013 Issue Of Cycle Source Magazine
This month in this FXR special issue, we will be installing a 2007-up Twin Cam 6-speed into an FXR chassis. It can be done, but you will need to cut weld the frame. Your main concern is going to be that the complete drive line will bolt up at the pivot shaft and front rubber mount, and fits in the frame. Everything else in between will come out. You will lose both cross members, kickstand, rear brake master cylinder, and mid peg mounts. Now a lot of people don’t realize the 2007- up motors and transmissions are all new cases and internal design. They are all internal oiling. The smallest bore is the 96” and they are only offered with fuelinjection. I would recommend buying a complete wrecked bike. The small stuff you can utilize is priceless. I bought my first donor from the Just Truck and Van Wrecking Yard. They were going to crush it and scrap it. Thanks Cori and Rhett.
First, get yourself a nomad to do the dirty work. Cut out the cross members and clean up the frame. After this is done, you can start your first of many mock-ups.
It is well known that the FXR frames were hand built. That being said, they are all a little different so each build will require different modifications. The best advice I can give is to measure and check all clearances many times. Assemble the bike and align the drive assembly before welding anything back together. That is very important. If you are an FXR fan and you don’t know how to align your bike, then learn! It is very crucial to the handling characteristics. If the engine, transmission, or swingarm were ever removed, you should at least check the alignment.
Once you triple check all the mounting points and alignment, it will be time to figure where to locate new cross members. It is necessary to add strength back to the frame. I added one between the engine and tranny, and one cradling the tranny case. I made them a thicker gauge than Harley originally did. I also added the much needed third engine heim joint. I can’t stress enough how that modification alone made the bike handle. I own 5 FXRs and this one will out corner and handle any other. I have yet to ride with a Softail or Dyna that can hang in the turns.
There are a few things that you will have to figure out. First, is what to do about a new kickstand. The old mid peg mounts will be gone, so if you’re a real FXR fan you will want to come up with completely new mid peg mounts and controls, modifying the primary case to work with mid shift. The 2007- up models use floorboards only, but forward controls will still bolt on for an easy way out. So, relocate the rear brake master cylinder. In some cases, the motor mounts will be modified (cut and weld), or you might have to shim the front mount. As I said, each frame is different. Now you can build your own exhaust, too. Then comes making a fuel-injected engine work with a carb. You will have to modify an intake manifold because nobody makes one. The ignition will be a problem, but there are some aftermarket companies making parts that will work.
The end result is worth it if you would like to own the best handling Big Twin bike with the latest mechanical drive line. It is nice to have parts available at any dealer when traveling across the map. Not that you will need them; no more leaks and hopefully many miles before a rebuild. I have 44k on mine and the only thing I will need to do is a cam swap. I’ll bump up the cams for a little extra power and rid my bike of cam chains. Other than that, I hope to put 100k on it before a build. Have fun and launch hard!