Running too lean.

[ultralight01]

So I took my birel kart out again today. As I was driving it a puff of white smoke came out of the exhaust. Before that the kart had slowed down to a quarter speed for about five minutes until I finally pulled over. I believe, considering the backfiring on deceleration, that the engine is running too lean and overheating. My carburetor has a fuel ratio adjustment screw. Which way do I turn it, and how much, to make the mixture more rich?



Thank you, I can post pictures if needed

 

[itsid]

depends on the carb but usually it's a righthand thread... means rightytighty leftyloosy as usual..

the tighter the needle in the jet the less fuel can move past the needle of course.

1/8th of a turn at a time until the engine runs best.
once there, 1/16s to maybe find a sweeter spot

'sid

 

[tinamcjittles]

Or if you want to be sure before messing with the screw, put a propane torch in front of the carb opened up a bit, if it bogs down then it's running somewhere in between.. If it revs a bit then it's lean! Plenty of people probably already know this, but it helped me a ton!

 

[ultralight01]

In front of the carb... You mean heat up the carb? Interesting. Thanks Sid, so loosen the drew a tad, then drive it, then loosen it again? Man I hope I didn't hurt the engine by overheating it about 4-5 times. That's why it was bogging down, not so much that the carb was dirty... (I cleaned it and oiled the air filter)

 

[Poboy kartman]

No...unlit propane torch!

 

[ultralight01]

In front of the air intake or the carb itself? I can't see how this would make a difference

 

[bob58o]

In front of the air intake or the carb itself? I can't see how this would make a difference

If there is not enough fuel (too much air) more fuel (propane) will make it rev up.

If the mixture is right or rich, more fuel will slow it down.


I THINK THIS IS THE IDEA, BUT I NEVER TRIED THIS.

Only something similar to look for leaks in the intake gasket.

 

[ultralight01]

Ok... interesting

 

[bob58o]

Also you can look at the spark plug and see what it looks like.

Hard to tell after just a short time of usage, but maybe it will tell something.

They say it is the window to see in your combustion chamber.

 

[ultralight01]

I think the spark plug has been messed up, there was the slightest tinge of black in between the wire connector and the plug. I'll look at it later.

 

[jandj]

Again, to read your plug for a specific condition, you have to kill
the motor during that condition.
For instance, if you want a read on WOT, you have to kill the motor with your foot down.

 

[Hellion]

In case there be any doubt, we should all be running our engines on the rich side of lean. It's what all the manuals say and have said for a generation.

 

[Bosch]

Again, to read your plug for a specific condition, you have to kill
the motor during that condition.
For instance, if you want a read on WOT, you have to kill the motor with your foot down.

^^ Truth ^^

 

[bob58o]

In case there be any doubt, we should all be running our engines on the rich side of lean. It's what all the manuals say and have said for a generation.

Manuals are for beginners.
Industrial Engines ...EPA standards, fuel consumption, constant RPMs,...

These engines have been designed to run lean, but why is lean better than correct? Wouldn't slightly rich be safer if the mix is not the Stoich (14.7 :1 of what ever it is) ratio?

I don't think that they had Go Kart racing in mind when they designed the carbs.

BTW, I like the lean side of rich better than the rich side of lean.

I lean more when poor cause I have more change in my pocket than when rich.

 

[ultralight01]

Haha, well, I adjusted the idle (EDIT: I meant fuel ratio) screw and ran the engine for minutes without it giving up. Should be good for another test run