"Houston, we've had a problem here"
Back on Mar 28th 2014 I had taken out my newly "upgraded" honda express nc50 noped for some test riding. The prior weekend I had take in out as well and experienced some technical difficulties... ie. It died on me. Once fully assembled with the following parts, I was able to start the honda noped first-shot. It was great. Now, keep in mind, I used the following stock express moped Mikuni carb settings on pilot run:
- Idle : 22.5
- Main : 185
- Needle setting (clip position) : default
The moped ran excellent for 30+ miles and unfortunately my Trail Tech vapor temperature gauge is not installed correctly, so I was running without and monitoring of engine temp. On my way home there was a half mile or so of flat open back-roads and I decided to test max honda nc50 acceleration. I was probably between 35-38 mph and the honda noped began to "buck" (like I was jamming on the breaks) and then finally the engine died and I cruised to the edge of the road.
At the time, I didn't understand the problem. I thought it might be electrical or perhaps something went wrong with the carburetor and the engine lost fuel. As see in this mopedarmy.com forum post, I experienced a Honda Express Cylinder Jug Soft-Seize. As you can see for the honda express parts photo at the beginning of this post, I had soft-seize the engine a few times 5-10. After the piston and piston rings had melted to beyond functionable, I was unable to start the moped because I lost all compression I had.
I thought the cylinder and piston were shot and I would need to drop at least $150+ for a new engine kit. Some suggestions I received included:
- Honing the cylinder
- Having the cylinder bored and adding a big-bore piston w/ rings
- Using a Muriatic Acid cylinder wash technique to remove the aluminum from the icon cylinder jug
Of those options I choose the Muriatic Acid Wash technique, because is was the least expensive. $60 for the Honda Dr 70cc 46mm upgrade piston. $7.29 for the Muriatic Acid. Some chemical resistant gloves, baking soda, Rubbermaid tub, goggles, air mask, paper towels... all things I already owned.
Next post reveals the video documentation of the process.