We weekend warriors set lofty goals for ourselves to show what we’re made of. We ditch the rattle cans for fancy coatings, put projects on hold until we can afford the best parts and push the MIG back in the corner to painstakingly lay TIG like dimes. But when I think back on the projects that gave me the greatest satisfaction, most hail from the days when the experience mattered more than the final result.
To stay grounded, it’s important to let loose every once in a while and do something just for kicks. That was the whole idea of our Amazon Diesel-powered Mini Bike project, and even we were surprised to see how easily something can come together when you abandon the pursuit of Instagram-level perfection.
With sunshine and good times here at last, our pet project has finally come to fruition; from a forlorn pile of parts to a fun-loving lil’ rig that makes you feel like a kid again.
Finishing Touches Our mini bike was mocked up and glimmering in the sun the last time you saw it, and it looked good, but far from finished. It needed color and an identity, and inspiration can come from the strangest places.
You may have caught a quirky old pool ball in some of the build photos, and it serves a unique purpose that we’ll touch on later. We opted to match the bad boy theme of the 8-ball with our color selections, and since we burned up all our budget on the reverse box, we’d be DIY-ing the finish on the cheap. But just because you’re doing the wrong thing doesn’t mean it can’t be done the right way.
We prepped the parts out thoroughly by sandblasting everything back to bare metal. I opted for semi-gloss black on the frame, as it always strikes a better balance in my opinion than matte or gloss. The center sections of the three-piece wheels received a similar treatment, along with all the bolts.
Spraying rattle-can white is a more complicated matter, though, as I’m of the opinion that white-white never hits the mark. Dover White proved to be the perfect shade, and we applied it liberally on the engine shroud and rust-pitted wheel barrels. Against the black centers, the pairing is money.
Our in-house vinyl cutter provided the icing on the cake, with a pair of retro 8X decals for the recoil cover and number plate. Why 8X, you ask? The 8 should be self-explanatory at this point, and everything’s cooler with an X tacked on the end. We’ll say it’s a play on our website if you’re looking for a deeper meaning than that.
Growing Pains If you tuned in for Part Two of our diesel mini bike build, you’ll recall that we encountered numerous issues with our initial mechanical configuration, prompting us to rework the whole driveline with a go-kart reverse gearbox. That got us moving in the right direction (pun intended), but it wasn’t the only time we’d have to go back to the drawing board.
It should go without saying that a little single-cylinder diesel engine like this produces significant vibration, highlighting several weak links in our custom components. The aluminum belt guard for the torque converter cracked at one of the seams almost immediately, so that needed to be improved. Worse yet was our exhaust pipe mount, which we had to rework twice before incorporating a small rubber bushing to allow some flex.
And then, there’s the 8-ball shifter. Considering the industrial nature of our Amazon diesel engine, it doesn’t come equipped with any sort of kill switch. Instead, you’re supposed to throttle the engine back until its fuel supply is cut off, but that doesn’t really work with a conventional motorcycle twist throttle.
We thought we’d handle this problem by bending up a sweet shift handle that was affixed directly to the governor arm. Topped with the ubiquitous 8-ball, the intention was that you’d push the shifter forward, moving the governor arm to the fuel-off position. It almost worked, but our first handle proved too heavy and rattled the governor arm back and forth while in motion, causing the bike to bounce from full fuel to none.
A shorter shift handle put less strain on the governor arm, but my prized 8-ball shattered in the process and had to be replaced. I’d be upset, considering the questionable origins of that pool ball, but one of my guys donated a new one to the cause, and it’s been on at least a half a dozen Toyota trucks he’s owned over the years. Certainly a worthy replacement.
But What’s it Ride Like? Like us, I’m sure you’re wondering if this thing would really work. I mean, we’re talking about a dirt-cheap diesel engine from overseas, intended to power water pumps, log splitters and other types of no-nonsense yard equipment. While not without its quirks, I can assure you that it’s just as entertaining as I imagined.
The Amazon diesel blows some serious smoke, way more than anticipated. While it doesn’t sound a whole lot different than a Predator 212, we’re certain no one will mistake it for one. Despite all the smoke, it’s not quick in a conventional sense, but I bet she’s capable of at least 25 mph. We might fiddle with the gearing in the reverse box at some point, but it certainly gets you around as is.
And then there’s the handling. Recall from Part 1 that we stretched the wheelbase a couple of inches to fit the diesel engine, and then examine the rake of the front end. I have no idea how this thing handled the way Sears made it, but it’s the embodiment of the phrase ‘turns on a dime.’ It feels like you can spin this thing around in a three-foot circle, and the lean angle is insane. One thrash section in the parking lot and I’ve all but eliminated the front chicken strips.
The rabbit-ear handlebars deliver their own special comedy to the handling situation, but they’re actually quite comfortable. As is the sprung solo seat, so pipe down, Tom.
That center stand off of our Honda CB550 project also has no business working as well as it does, but it holds the bike steady when you’re pulling the recoil, and the retention spring keeps it folded up when you’re thrashing. And don’t even get me started on the technical brilliance of the rear grab handle.
Let the Good Times Roll Ordinarily, I’d be thrilled to see the conclusion of a project, but I’ll be bummed to see this grin-enducing piece of hardware leave the workbench. Refining all the ridiculous ideas we came up with for this project into tiny working pieces gave me a whole new respect for mini moto, and I’d say yes to another mini-bike build tomorrow if we could swing it.
I’ve kicked the horse to death throughout this project, explaining that this is something you need to do. There are old junk mini bikes all over the web, brimming with character, and the parts to revive them are cheap as hell. If you have some time to tinker or are looking to dip your toes in the custom motorcycle scene, get an old mini bike and let your imagination run wild.
New here? Check out Part One and Part Two of our Diesel-Powered Mini-Bike Project.
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