Mule Funny Bike

This is the Mule Funny Bike rolling chassis, built by Richard of Mule Motorcycles, California. It was never fully completed, but we dig it. Here is Mule’s story. His views on C&J chassis are his, not Sideburn’s. We’ve never tried them.

“The ‘Funny Bike’ was the culmination of several ideas. It was supposed to be a chassis for a Buell motor to be ridden by Michelle DiSalvo who was a fast National caliber racer. It would be run in the ‘Supertracker’ class which allowed 1250cc 2 valve, pushrod motors (Harleys).

“Up to this point I’d built about 20-25 Street trackers using C&J frames, but wasn’t happy with many of the design features. So I decided to solve as many problems as I could with the first prototype. Some of the issues were: an exhaust system that hit your right leg; couldn't pull the motor easily; couldn't pull the top-end in the frame; overall side-to-side balance of the motor in the frame; oil capacity; inability to accurately check oil
Level; breather (cases) capacity; wheelbase with the 5-speed Sportster/Buell cases; fuel tank availability.

“Although the bike was never completed, many things were tried, designed, discarded, re-done and so on. I had a blast building it and plan to build another.

“The frame is a perimeter type. The right spar has several NPT threaded fittings for breather tubes to attach to the various breathers coming out of the motor. At the bottom the tube had a drain to return the collected oil back in the cam gearcase. The left spar has an additional tube that ran about 5" below it and was completely sheeted in to serve as an oil tank. Capacity was almost 4 qts(liters?). There was a fitting machined up and welded into the outer skin which accepted a oil window from an Yamaha XJ750 primary cover. This allowed a visual check for a minimum oil level.

“The rest was pretty straight forward, but stuff you normally don't see in the ‘Follow the leader’ world of flat track. A gullwing swingarm allowed one exhaust pipe to wrap under the chassis and sweep up under the upward arc of the left swingarm blade. In the event of a laydown/lowside, the pipe was only marginally vulnerable. The other pipe tucked inside the frame and wouldn't burn the rider's leg.

“The rear subframe unbolted for easy replacement and although I used a traditional XR750 type seat, it was made of carbon-fiber. The feedline from the left-side frame oil tank to the oil pump was huge. What was intended to be a simple swingarm pivot structure, ended up being a complex build, but provided a wider, stiffer, swingarm pivot dimension. Wheels and front suspension were conventional and the shock was tucked in, well out of harms way.

“The tank was never built but was going to be a very low, flat, pancake affair to allow the rider to tuck in very low for excellent aerodynamics on the Mile tracks.

“Two of the original design goals worked out very well. The top end could be pulled straight out the top of the frame and all top end hardware and components were readily accessible. Eight, easy to reach bolts would have the engine fall out onto the ground. No wrestling or shoehorning to re-install the engine. Just jack it up and it popped right into place!

“There were a few fit up details I didn't like, so
I cut the thing all to pieces to re-do several portions of it. It's all resting in a couple large boxes with only about 25% re-work completed. I guess I just moved on to several other, more pressing projects.”

Richard, Mulemotorcycles.net