The Evil Monkey got a fresh upgrade! I've had my 1976 Honda Z50 for nearly 10 years. It came with the original 50cc motor that I bumped up to 88cc with a big bore kit quite a few years ago. I've had a brand new Lifan 125cc (4-speed auto) motor sitting around that I was planning to use for another project. I decided that I'm probably not getting to that other project for a while so I might as well put the motor to good use.
Unsurprisingly, the 125cc motor doesn't simply drop right in and fit. The carburetor is the main problem. The bigger carb (I'm running a 26mm VM22) means a bigger manifold and the combination needs more clearance. I ended up cutting off the front tank mounts and welding on new ones 1/2" higher than the old ones. I added aluminum spacers and longer bolts to mount the footpeg bar and it needed a new shift lever. I also made a simple exhaust bracket and riveted it to the muffler. I ran this exhaust before without it, but I really needed to keep the can in a specific position to prevent the pipe from burning my plug wire from the coil. Speaking of wires, I did have to redo some wiring and hide the CDI under the seat. Lifting the tank also helped me hide the wiring harness. I still have my lights hooked directly to a battery and am not powering them off the motor. It just keeps things simple, which is what this little bike is all about.
Before even attempting to start the motor, I drained the original oil and added fresh. While the bike ran with the carb straight out of the box, swapping the jets certainly made it run better. It just took some trial and error and find the right combination. The giant rear sprocket (45T) I've been running means the bike remains geared for torque over top speed and that's fine, though I am curious how fast it would go with a "normal" gear ratio or one geared for speed.
So far, I'm pretty happy. The bike feels more powerful than it did and I like the blacked-out motor for the aesthetics. I'll admit I was hoping for a little more of a "wow" factor going from 88 to 125ccs but I might need to throw on a 37T sprocket and see what that's like. It's weird to think this bike and my Grom now have the same displacement, but the Grom is definitely faster (again, gear ratio is probably a big factor). That said, I'm not sure that I'd want to be doing 50mph on this bike anyway. I don't have the front brake hooked up so I'm just relying on the single rear drum to slow me down.
The new Honda Monkeys are also 125cc, but they are much larger than the vintage Z50s. They're cramming in a lot more features, electronics, and do-dads to make the bikes faster, safer, and street legal and the new ones are focused on adult riders so it's not surprising they're larger. The ol' Evil Monkey remains a stripped down little hot rod - big motor in a little frame.
While it's looking good here basking in the setting sun of early-fall, I think the bike looks its best as its alter ego, the Snow Monkey. While I'm certainly not wishing away fall, I look forward to the pairing of the 125cc motor with the banana ski sometime this winter.
