How can you tell if your running rich or lean?

[Dawelny97]

Hey all, I have a 53cc 4 stroke huasheng that I got installed. It wouldn't clear my frame with the outer part of the air filter box, so I left the inner part of the airfilter box on (just the side with the bolts exposed) and ziptied the foam on. It works well, but I would assume its running lean since it now has more air flow. When I tried to start it for the first time, it did not want to start at all. Choke or not. It would start if I gave it half throttle when pulling it, but then immediately die. Weirdly enough, turning the fuel screw 3/4 of the way out from seated allows it to start first pull and idle normally. Isn't this leaner? When I tried to make it richer, around 2 turns out, it would stall and die and white smoke would come out of the carb. Is this normal? So I put I put the fuel screw back on 3/4th of the way out and rode it for around 20 miles or so. I take the plug out and this is what it looks like. Am I running rich? lean? I've tried looking at the forums for answer and I couldn't figure this situation out.

 

[FOG]

Plug looks good and what you're thinking is a fuel screw is probably an air screw so it's the other way around. Out is more air. Leaner. In is less air. Richer.

Ride On!

 

[Dawelny97]

On the huasheng carb? But the screw to adjust the air/fuel ratio is closer to the engine than the air intake side of the carb, doesn't that mean its a fuel screw? Im sorry, im new to these small engines and the concept of carburetors. Oh also by the way, when I took the spark plug out it wasn't a plug chop. Its the same plug ive been using since I first got the engine. That doesn't affect the info the plug can give you right?

 

[FOG]

I'm no expert on Chinese carbs, that's for sure, but, in general, in the idle circuit your fuel comes from a pilot jet. In Japanese carbs that pilot can be tuned with different sizes just like a main jet. Dunno about Chinese.

The fine tune is the tapered air screw. The air typically gets fed from a separate passageway you'll find in the mouth of the carb. Where the designer/engineer put the screw doesn't matter.

 

[Dawelny97]

I'm no expert on Chinese carbs, that's for sure, but, in general, in the idle circuit your fuel comes from a pilot jet. In Japanese carbs that pilot can be tuned with different sizes just like a main jet. Dunno about Chinese.

The fine tune is the tapered air screw. The air typically gets fed from a separate passageway you'll find in the mouth of the carb. Where the designer/engineer put the screw doesn't matter.

That makes sense. So I made it richer by turning it only 3/4 of the way out which is why it can run now. I read somewhere tho that if you have less than 1 turn or more than 3 on the screw that you need to change the pilot jet. Is this true? Also do you know the correct setting for the screw on the 4 stroke huasheng?

 

[FOG]

I read somewhere tho that if you have less than 1 turn or more than 3 on the screw that you need to change the pilot jet. Is this true? Also do you know the correct setting for the screw on the 4 stroke huasheng?

Probably some truth to that but I wouldn't worry about it. I've got 5K miles on a Vintage 360 Yamaha at 7/8 of a turn out and really, the correct setting is where it idles and starts the best.