Huasheng design flaw?

[DavidCP]

Something I have noticed about my Huasheng engine is that it runs way too rich. I had suspicions given how the throttle response cut out about halfway through the RPM range but it wasn't until I spark plug tested it that I knew for sure.

The engine managed to heavily blacken a spark plug with only about 80 miles on it. I was wondering why I had to replace the engine oil every 80 or so miles despite using the choke correctly.... now I know why.

So after replacing the spark plug yet again and changing the oil, I made an adjustment to the air filter box. The stock engine relies entirely on engine pressure to draw in air from the bottom of the engine air filter box.

So I drilled a grid of small holes (about 2 mm each) into the front of the air filter box to allow momentum to help provide extra air too. The engine is now responsive through the entire RPM range and much smoother than before.

 

[wheelbender6]

Good idea. I guess its not possible to rejet the stock HS carb.

 

[CrazyDan]

I guess its not possible to rejet the stock HS carb.

I rejeted my stock carb with a micro drill bit set (#61-#80). Drilled out my main jet till it bogged, put in a bead of solder and used the next smaller bit. Runs like a champ now. Also remove the brass plug closest to the engine on the carb. Use a smallish drill bit to pop a hole in it then twist a screw in. Use the screw to yank the plug out. Idle jet is adjusted under there.

 

[DavidCP]

Good idea. I guess its not possible to rejet the stock HS carb.

Ohh no a person can rejet the stock HS carb. I just chose not to because this was much easier.

To me it made more sense to allow more air in rather than limit how much fuel gets past.