The sketchiness of the deal was obvious from the moment I rolled into the driveway.
Thirty miles of winding tree-lined roads lured me into a neighborhood of stuccoed two-stories that materialized out of the Florida wilderness like a swamp forest Brigadoon. I was here for a long-dead 1971 Honda CL100 Scrambler, and as I turned off the road on this summer afternoon I was greeted by what looked like a driveway archeological expedition.
Parts of everything were everywhere, exploded out from a two-car garage; ancient Volkswagen transmissions, rusty bicycle gears, nondescript cylinder heads from Hirohito-era Japan. It was like rolling up on an aftermath. The war must have been horrible.
The Scrambler had 1,054 miles on the long-since-broken clock, which jiggled in its rotten rubber mounts as I rolled it on cracked, flattened original tires up the ramp into the back of my beat up white Ranger. I was now owner No. 2.
I’d bargained the Cobain-haired second-generation hippie seller down to $350. I figured I could pull a Frankenstein on the tiniest motorcycle I’d ever owned. Fittingly it came with a box of spare parts from other CL100s whose fates went unmentioned.
When I stopped by my brother’s house on the way home, his 3-year-old son hopped onto the bike in the back of the truck and, to my horror, it looked to fit him perfectly. “You meet the nicest people on a Honda,” a contemporaneous ad campaign read back then. The nicest toddlers too. Those famous magazine ads featuring a slightly smaller Honda 50 riding two-up must have had models on it the size of chimpanzees.
Step 1: Making sure it’s not a lost cause
The diagnosis on the bike took seconds after the autopsy began on my back porch. The engine was seized, and that’s why the bike was dead. But, to quote Miracle Max, there’s a big difference between mostly dead and all dead. Mostly dead is slightly alive.
When an engine sits for a full decade undisturbed, the disparate steels, brasses, coppers and aluminums inside begin a slow orgy of metallic oozings. Spark plugs seize to cylinder heads. Valves weld to seats. And piston rings rust their way into cylinder walls by force of time alone.
I’d seen it before, and knew this one wasn’t bad. Standing water in cylinders ruins engines in a hurry. Humidity only makes it seem like that’s happened.
A soak of sparkplug-hole PBlaster for an hour (while cleaning a decade of varnish out of the carburetor) and some working the bike back and forth while it was in gear freed up the piston. Then I poured some automatic transmission fluid in to help hone what was still sticky in the bore.
Within an hour I had the bike running. For the first time in my life I kickstarted a motorcycle’s heart with a human leg and was greeted with a rattly roar through a rustily swiss-cheesed high-pipe muffler blasting exhaust every direction. Importantly, it didn’t smoke, aside from looking like it ran on coal for the first 30 seconds clearing out the ATF.
I immediately commenced clumsily hooning it like an escaped circus monkey around my bumpy backyard after finding out the clutch discs were so seized it leapt forward the moment you put it in gear. It was a hoot immediately. I may have started hooting along with it. This also nearly ripped the original tires in half as I cut figure eights with a grin unhindered by flying dirt.
Step one complete. The bike was now worth a few hundred dollars more than when I started an hour ago, because I could at least prove it ran. And it ran shockingly well.
It was time to make it more fun. That meant a total teardown to clean the thing up and make it look like a cross between a prewar bike and a mods-n-rockers throwdown special.
Step 2: Breaking it down
Usually disassembly is the hard part, because after four decades things get rusty, frozen, or just plain snap off in your hands. You usually need a lot of PBlaster for this step, and maybe a torch to kill all the wasp nests.
Freakishly none of this happened with the Honda. Almost every bolt turned free right away. That was not the case with any 1980s UJM I’ve owned, which would fight you until they knew you’d bled. They just know somehow. With this bike, it was like a zen moment, only with delighted cursing.
Important tip: Write down where the bolts came from and put them in bags. This is the step I always skip, because I always optimistically think I’ll be done in a week or two and will remember where everything goes. Then the headliner starts sagging in your 25-year-old daily driver BMW, then a chain reaction results in the whole car in pieces as the motorcycle on the back porch is slowly consumed by the earth and raccoons make off with the shiny parts, known among their people as “the harvest.”
Step 3: Building it back up
I regreased everything internal. This bike is listed with a top speed of 55mph, which I’m pretty sure is the sound barrier, so I didn’t want to have an axle explode.
I cleaned and repainted the black stuff, including the worn chrome wheels, sanding with 220 and 320, priming and blacking them out with semi-gloss. I polished everything that I was going to keep metallic, and then went to town with a pressure washer on the engine, being sure to seal it up first. You’ll need a lot of Simple Green or other degreaser for this, because grease is more tenacious than a raccoon with a stolen swingarm bolt.
I bought Michelin Gazelle moped tires for $20 each on Ebay, which is just shockingly cheap. The CL100 has nearly bicycle-thin wheels, so I got the chunkiest tires I could fit on them (that I could find, at least) without exceeding the stability of the rims and still clearing the swingarm and fork, 2.5 inches up front, 3 inches in back.
Tire spoons are a great tool to have on hand when tackling a tire job on a bike. Keep in mind the taller the sidewalls on the motorcycle tire, and especially tubeless tires, the easier they are to swap. I did it with two spoons, but on stiffer tires it’ll take three. I cut up a milk jug handle and used those pieces as plastic rim savers. This took maybe 40 minutes, going slowly.
Step 4: Doubling the voltage
The rewiring job was the biggest thing on the whole bike. I planned to clean out and relocate or eliminate everything underneath the triangle formed by the frame spars under the seat, so that it looked cleaner. That required cutting and welding a frame to hold the electronics and battery horizontally under the seat. With some scrap steel, a $100 Harbor Freight 100 amp welder (still works great after 5 years) and a little mockup that didn’t take long.
What did take long was the damn handlebars. I wanted lower, blacked out ones to go with the rest of the bike, and as is my MO, I do not cut up original parts unless they’re ruined; I save it all.
I bought my favorite go-to cheap dirtbike low-rise, moderate-pullback handlebar from a nearby Yamaha/Kawasaki dealer for $20 and cut it up to fit. That involved fitting it for an odd slide-throttle that required a precise half-inch wide channel to be cut horizontally across the right side of the bar and filing it like crazy to make it slide smoothly. Lacking a few grand for a CNC machine to do this, I pulled it off with an angle grinder and dremel. Thankfully the Mad Max aftermath is covered up by the throttle handle.
I also had to slice holes in the bar to run wires through it like the stock one. I suppose that hidden wiring kept tree branches from catching wires when riding through a forest with reckless abandon. It would not stop them from whipping your face off. And it was kind of a nightmare to do.
Rewiring the bike also entailed converting the bike to 12 volts, as it was a 6v system in the first place. That’s the only way I could get all the fancy and, importantly, low-amp-draw LED lights for the bike.
The nice part is a stock 6v voltage regulator will just adapt on its own to a 12v battery, normalizing its voltage to that battery, so you don’t need to change it. The low amp draw of the LEDs cancels the lower amps put out by the stock stator at 12v.
So I bought an integrated taillight (tail, brake, turn signal, license plate light) on Ebay for maybe $25 and hooked it up under the seat, fabricating a custom mount for the license plate below it. The LED turn signals require you get a different LED-friendly flasher relay that actually lets them blink, or install a resistor inline with the stock flasher’s wiring.
After I was done with all that, I built new mounts for the speedo and headlight to drop them 2 inches so they’d be more in line with the bike.
Step 5: Final aesthetics
I wasn’t planning on off-roading, so I lowered the bike by cutting a couple coils off the bottom of the springs. I don’t consider those cuttings sacrilege because the springs were pretty badly pitted with rust before I got to them. I was conservative with the cuts so they don’t go into coil bind. Thicker fork oil than stock (and new seals) also helps keep movement tight.
I wanted to keep the look of the stock high pipe muffler and thankfully it was simple steel underneath the bolt-on chrome heat shield. I found some scrap steel again and welded patches into the back of it (where all the holes were). Easy stuff, minus the slag burns.
It now sounded great and no leaks. Firing it up again was a great moment. With a new pod filter on the carb and slightly richer jetting, it kickstarted right away with a shockingly menacing rumble for being just a 100 cc.
After riding it around and pulling off two labor-intensive wheelies I decided to make the gearing taller. The best I could do was a tooth up in the front and two down in the back, because that’s all I could find that wouldn’t have to be custom drilled or machined. This is a budget build (remember, the bike cost $350).
Total cost sunk into the bike was less than $500 for a very fun monkey-friendly urban runabout that can now top out at above 60mph (indicated), which is just nuts for 100 cc. Worth it?
Isaac Babcock has worked as a greasy-nailed journalist since 2002. He popped his first wheelie at age 25 and has only come down to go to the bathroom.
Got a bike build story you want to share? Email us at email@example.com.