Project Car SOTU: Bultakenstein & The Honda CL125S

IMG_0137_web My custom Bultaco roadster project, which I began in earnest over 2-1/2 years ago, is still not quite a roller. Readers familiar with the project would be excused for thinking that things have stalled, however “stalled” isn’t really an applicable term to this project, given its nearly glacial development. Like one of NASA’s crawler-transporters headed toward the launch pad, things are steadily crawling forward, albeit at an extremely slow, careful pace. I knew it would take years to complete when I started it, so that’s okay. Now on the other hand, I bought the CL125S to ride, not wrench on eternally. And yet, despite buying it in nominally running condition, I have not ridden it a full mile so far. That’s kind of a bummer. …And the bad news keeps on coming.


For the new kids in class, I’m building Bultakenstein from scratch out of pretty much random salvage parts — whatever I’ve stumbled across cheaply. A big goal (perhaps the most important part) of this project is teaching myself the skills necessary to work on real vehicles with confidence. My desire was for a fun diversion in the building, not getting to a finished motorcycle to ride. I made a conscious decision not to let it take over my life, so I have allocated only fairly meager resources toward it — currently $50–$100 and 10–15 hours per month, much less when life has more pressing demands. The resulting conundrum is that the cheapest way of accomplishing something is usually the most time-consuming, and the quicker ways take more money. So far, I’ve chosen sweat equity over whipping out my wallet. Thus, I’ve been fabricating with fairly basic tools: a drill press, a hacksaw, a few files, some bi-metal hole saws and a couple of metric taps. That’s about to change, however. IMG_0357 The most recent component I’ve been making is a front shock mount. I am attempting to over-engineer everything, due to my ignorance, so this pair of mounting plates will tie into the main frame backbone at four different points. I’m making them out of quarter-inch alloy plate, partially because I want to gain experience working with aluminum, partially because it takes gobs less effort to cut, shape and file than steel. The two plates will attach to either side of the frame with through-bungs, which are designed so that should my amateur welds fail, they will remain captured and not fly completely apart. Like I said, I’m trying to be smart enough to recognize my ignorance. Once I get the mounts in place, I will truly have a roller, and I can move on to the engine. The good news is that (for the most part) all the parts I’ve purchased for the engine are designed to go together without modification. No more trying to make stuff from two different manufacturers match up properly. I will welcome that change. Furthermore, I’ve rebuilt Bultaco engines before, so it won’t be virgin territory for me. One big reason for this project’s almost geologic gestation period is that at the start I had no workshop beyond simple hand tools. Since then I’ve purchased a few bigger, more badass tools and equipment — drill press, MIG welder, air compressor and air tools — and spent time learning to use them. But tools are damned expensive. The good stuff isn’t cheap, and the cheap stuff isn’t good. Since I don’t have an unlimited budget, I’ve put a lot of research into finding the sweet spot in the compromise curve. The result is that I bought a small 110v MIG welder, but I got one with a wirefeed gun that can do aluminum. I bought a small 5 gallon air compressor, but I bought one that has a fairly high capacity oil-lubed compressor pump, instead of the louder, wimpier, less durable oilless type. But throughout this project, the thing that I’ve desired more than anything else is a metalworking lathe. Hand tools are not just slow, they are also inherently inaccurate. I don’t care how long it takes me to finish Bultakenstein, but I don’t want to end up with a piece of utter crap when I’m done. To build something that works decently well, there are certain dimensions you can’t freehand (unless you’re Allen Millyard). A lathe is the one tool that can make nearly any part accurately (or create a fixture or jig that can allow something else to make it accurately). Enter “Baby,” my newest addition to the garage: IMG_1579_web

The top shows the custom shock spacers you make when you don't have a lathe. The bottom shows the ones you make when you do.
The top photo shows the custom shock spacers you make when you don’t have a lathe. The bottom shows the ones you make when you do.

Keeping with my quality-over-capacity tool strategy, I’d picked out the Taiwanese-built South Bend 8K bench-top lathe as a the one that would best do what I’d need but not be too big, too expensive, or too shoddily built to be worth buying. Add to that, they’re currently being blown out at a deep discount. Cue Mrs. Tanshanomi. She knew I wanted one desperately, but also knew that I would never ask her to spend over $2000 to equip me to build a bike that would never be worth half that. So, she surprised me with a new 8K for my 51st birthday a couple of weeks ago. Wow. This makes all the difference in the world. Unfortunately, Catholic prep school didn’t prepare me in the manual trades, and I have a lot to learn. My time has been taken up lately reading machinist forums and learning how to set up, align, lubricate. Even a factory-fresh lathe is not a turn-key operation. Lathes are like guns; you buy a brand new one and then have to take it completely apart before ever using it. I have also learned about all the other stuff you need to run a lathe; I’ve spent about $600 on additional accessories and supplies, including having a dedicated 20 amp circuit installed. I have made exactly two parts for Bultakenstein so far, and they’re much nicer than anything I’ve been able to fabricate in the past. They are actually a bit fancier than absolutely necessary, both for aesthetic appeal and practice making and duplicating complicated shapes. Learning to use a lathe is akin to learning to play a musical instrument and — to stretch the analogy — I’m learning to play basic scales right now. So far, the trip down the hobby machinist wormhole has been almost embarrassingly fun, and will pay dividends far into the future, until I’m too old and frail to wrench on anything at all. I’ve been documenting the Bultakenstein project in minute, some would say excruciating, detail over at but, sadly, the tone of that forum has taken a rather absurd turn for the worse lately.

The Honda CL125S

My other recent acquisition has turned out to be a much less “steady-as-she-goes” project. As I shared when I bought it back in April, I picked up the CL because it’s nearly identical to the first motorcycle I owned, back in high school. I thought it was a basically solid survivor that would only take a bit of freshening here and there to be streetable. It is not working out quite that way. The first obvious problem I’d missed before purchasing it was the condition of the exhaust. The rarer CL125 is nearly identical in construction to the more popular, long-lived CB125 street bike. The big difference was the beautifully designed scrambler exhaust. It’s my favorite thing about the bike, and also the one part that is virtually unobtainable. IMG_0324_web When I test-rode the bike, it was obviously missing the crush washer between the pipe and the head; I thought that explained the loud exhaust bark. I was only partially correct. The muffler was also completely rotted, with a hole large enough to fit three fingers into, without touching the sides. That’s kind of a big defect to miss, but it was hidden on the lower inside of the muffler in the one place I didn’t examine closely. The good news is that its hard-to-see location makes this a perfect opportunity to work on my sure-to-look-kludgy welding skills. IMG_0303_cropped The exhaust has been welded on previously. The mounting bracket at the front of the heat shield hid ugly corrosion that received some remedial strengthening at some point in the bike’s life. Again, it’s not tragic, but it’s another example of how much harder this bike’s life has been than I thought. Another detail that differentiated the CL from the street version CB was the lack of a tachometer. To compensate, Honda put some really nifty shift range indicators on the speedometer face. My speedo is inop, and makes an annoying clicking sound underway. Since the instrument binnacle is one of the components most prominently visible while riding, I would really like to keep the original design, but the cheapest replacement I’ve found is over $200. Kilometer-marked knockoffs from Asia are available very cheaply. The slightly different CB125S speedo will work, and good used ones are plentiful — they’re just not as cool. Perhaps I can swap the face, though I’d guess they’re too cheaply constructed to be easily disassemble-able. I’m pondering this one. IMG_0344_web The fuel tank had two large dents on the left and top, so I began carefully massaging the metal closer to its proper shape. Once I’d gotten it close enough to finish with a skim of body filler, I started cleaning off the many years of crusty crud that had accumulated on it. That is when I found that the bottom of the tank was in much worse shape than I expected. IMG_0302_cropped Pinholes of rust weren’t leaking only because of the thickness of the corroded grime hiding them. Who knows how many more spots are on the verge of breaking through. Taking my amateur MIG welding skills to this sort of thin, weakened metal is an invitation to simply make things worse. I really need to solder or braze the holes. That takes an oxy-gas torch, which I don’t have. Time to go tool shopping again, I suppose.

Leave a Reply

Your email address will not be published. Required fields are marked *

The maximum upload file size: 64 MB. You can upload: image, audio, video. Links to YouTube, Facebook, Twitter and other services inserted in the comment text will be automatically embedded. Drop files here