This Honda SL125 was my latest impulse buy… and a great decision

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I have a thing for fixer-uppers—I can’t let a good project get away. I’ve had to reel myself in lately, though, since I am quickly accumulating a piston orphanage.

I broke my own rules when I picked up a Honda SL125 at the Barber Vintage Festival swap meet. In an odd turn, I haven’t talked myself out of it, and now I’m actually more convinced than ever it was a good purchase.

I took two motorcycles to the Barber Vintage Festival, and by the second day I was down to just one after selling a late-’70s Yamaha to friend I was camping with. This meant I had a small amount of cash and some space on the ride home for something new—or, at least, new to me. After passing up a sweet vintage trials machine, I stumbled upon this 1972 Honda SL125.

My experienced eye immediately picked out a few good signs. Chunky tires that looked fresh, seat in excellent condition, paint on the tank. The chain and sprockets looked good, too. That was enough justification to stop and take a closer look; there had to be something I wasn’t seeing that would keep me from buying this.

True, the Honda was rough around the edges. It was missing its factory lights, the once-keyed ignition was now just a toggle switch, and the engine case had been painted at some point but was now flaking off. Nothing that couldn’t be handled in a few weekends of work.

Honda project
Honda project

Honda project

Then came the hard part; there was no price on the bike. This is a massive pet peeve of mine at swap meets. Oftentimes I’ll just walk away from non-priced items like this because I assume they are out of my price range. Happily, the friend I was strolling around with read my interest and broke the ice with the seller. Expecting to hear a four-figure number, both of us perked up a bit when the seller came back at just $600. He also mentioned the bike had just received a fresh cylinder and piston and ran strong.

A little haggling later, I was happily puttering back to my campsite on a pretty little SL125. As I loaded the bike and headed back to northern Michigan, I began to wonder what I was thinking, buying a motorcycle just to take it where the riding season is certainly winding down. I have a Model A to work on, among other projects in the garage, but this little Honda could fit in my basement, where I could spend evenings fiddling away in warm comfort.

Justification enough for me.

Before tucking it away, it was worth getting the Honda running like it should. Riding around the grounds of Barber, the bike had power, but it didn’t feel like all 12 factory-rated horses were showing up. It also was a real pain to get the engine started. Multiple times I tried to start the bike only to give up and hop on my trusty Kawasaki KE175 and leave the fiddly four-stroke in a cloud of two-stroke exhaust smoke.

The seller highlighted what I thought was the problem: a knock-off overseas carburetor bolted to the cylinder head in place of the factory-fit carb. Initially, the plan was to find a period-correct carb and replace this modern piece, but the search proved fruitless. Well, I thought, maybe it was just out of adjustment.

Honda project
Honda project

Honda project

The knock-off carb on the bike is a replica of the original unit, so I figured maybe the base settings for the factory piece would get me in the tuning window. I started by pulling the carb off the bike and cleaning it thoroughly. Both the main jet and idle circuit were clogged with a nasty jelly-like substance. Using the factory service manual and a flathead screwdriver, I set the adjustments to factory settings and reinstalled.

A couple tickles of the kick starter and the engine lit off. Then I proceeded to annoy my (very kind and patient) neighbors by idling and sputtering around on the bike while making small adjustments to the mixture screw. After 20 minutes or so, the bike would idle strong and had minimal bog at throttle tip-in. It also started second kick, even cold. 

Getting the bike running right was rewarding, and I expect that to be the theme for this entire project. Just little repairs and upgrades here and there, using the bike to teach folks how to ride and playing around in the dirt myself. Maybe I’ll get carried away and turn it into a bike I can commute with to the office or take it ice racing this winter

The options are endless. If you have ideas for this neat little custom bike, leave them in the comments below. I would love to hear some ideas.

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