When the Cranks first formed, we met a guy named John Juke who thought mopeds were pretty nifty and wanted to get into the game. I found him a Batavus Regency top tank on craigslist and we went on an adventure to go get it a few hours away. After getting lost a few times, we got to the house of a very excited gentleman who was selling off a sizeable 'collection' of hard-luck motorcycles and outboards following a messy divorce.
We bought the Regency for Juke as it was in immaculate condition and reasonably priced, and as we were leaving the seller mentioned having another moped 'for parts' on the other side of the barn. After pulling off the CB750 sitting on top of it, I could tell it was a Sachs Balboa, red with mags. It was covered in bird crap and had been outside for a while, but otherwise was in pretty good shape. Surprisingly the paint had held up pretty well, and aside from some minor things missing, controls, carb, etc. It was all there. The best part, the price, $50 and with a title no less!
I couldn't resist, despite my previous experience with sachs engines on Blaze's completely hammered columbia commuter, it was too good to pass up. We crammed both bikes in a 5 door VW Golf and drove home to milwaukee.
My first plan for this bike was to keep it simple. I was looking forward to having a reliable, if not all that fast, platform with sturdy suspension, big tires for running over stuff, and wiring, etc. kept tidy and secure. The original version, completed sometime XXXXXXXXX had a mildly ported 'C' cylinder, SHA 12 carb drilled to 14mm, and a Simonini Circuit pipe originally meant for a Peugeot 103. I made a bunch of trick parts to get it on the road, including converting front and rear snowflakes to run 12mm bolt axles and sealed bearings, a tricky underside mount to support the 103 pipe, modding the SHA carb to fit by trimming the idle needle down and shimming the intake, and a really clean hard-wire with a sturdy screw-type terminal block and tons of soldered connections and heat shrink. I was pretty proud of the bike because it was basically the best possible work i could do at the time.
Somewhere in the hubbub of the Fortress and piles of junk, the engine fell with the cylinder removed, breaking off the upper skirt (the one that closes the intake port). I figured flipping the piston would be an easy fix, and honed the cylinder and installed new rings.
I rode the bike as it was for a while and it was ok. Not great. The gearing, like most sachs, was super short limiting top speed, and for some reason it never had much torque. I blamed the stock 'C' short stroke crank for low compression and started looking for a good way to improve the power.
A few months later, Blaze called it quits on the columbia commuter. He had purchased an 80cc Athenakit for it, and him and I really didn't know shit about mopeds. We came to find out that there was a lot more to kitting a bike than bolting the kit on. We tried making a custom intake manifold and mounting a china-clone Keihn 22 mm carb on it, we had it running barely and the stock exhaust kept falling off. A few rides around the block with the forks flopping around, the rear wheel severely bent, and the exhaust falling off, and we decided my Balboa would be a better home for the 80cc power.
I bought the kit from Blaze and started setting up the Balboa to go faster. A laughably bad custom aluminum intake was fabricated to clamp to the kit's intake and wrap around placing the carb above and next to the engine. This fell off the wednesday before K'zoo bbq14, when Zack and Nate bandit came into town on their way riding to the rally. There was much joking about my terrible design and overthinking the problem.
The original reason for the slow performance of the original cylinder was determined to be broken rings, flipping the piston put the ring pins into the exhaust port... d'oh! Both rings were smashed to bits and partially stuck in the piston. Its amazing how well the poor thing ran regardless.
The clutch started acting up right away and was fixed by swapping parts from several motors to make a 3/4 clutch pack. A toothed washer, loctite, and an impact wrench stopped it from spinning off.
A 38 tooth sprocket was sourced from handybikes to get my gearing a bit taller. The clutch didn't like that much but the revs were kept to a reasonable level and the kit had gobs of torque to spare.
At bbq14, I spent a lot of party time trying to keep the bike together. The bracket holding the pipe on couldn't handle the added vibrations of the engine running faster and broke, this caused the pipe to break almost immediately and continue to break over the weekend. I was able to fabricate a new mount at Chad Burke's shop out of some metal scraps, and re-weld the pipe together, but major triage was needed. That experience convinced me quickly that the one speed engine wasn't going to cut it.
I started looking for a 2 speed manual and quickly found out that my friend Roald in the Netherlands had a friend who was selling one. I had just purchased 2 ZA50 maxi's and Roald wanted to trade. He got a mint condition ZA with 500 or so miles on it, and I got a complete but abused Sachs 2 speed, with a long-stroke crank, and a 'new-ish' clutch. I felt like I got a pretty good deal, as these things were still pretty rare stateside at that time.
The 2 speed build started with the lessons learned from the 1 speed. First of all the china clone carb was going in the trash. I had traded somehow or another for a VM18 clamp mount carb that I thought would be a nice alternative. I had redesigned the exhaust mount bracket a while back, and finally did a production version of them, plasma cut and powder coated. The athenakit was blueprinted and ported heavily. For a reedvalve it had a port map like a piston port, very short intake timing, and an awkwardly shaped exhaust port.
The two speed itself had a bunch of new challenges. The shifter that came with the engine was not only the wrong shifter, it had the lever from one kind of shifter with the base from another kind. I had no cables, no mounting brackets, and no idea how to hook them up. It took a lot of mangling to get it all sorted out, and its still not the best, but the clutch works and it shifts gears when and where it should.A lot of dremel machining got the lever to fit and do what it is supposed to do- lock into each gear position when the clutch is released.