I adjusted the bottom fron screw on the carb(hitachi ea81) by turning it 1/2 turn out.

 

I remembered that a few years ago ( the last time I had to pass emissions) that I didnt originally pass until I turned that screw out about 8 turns ( I know it seems excessive, but I scored a.01% carbon monoxide with 12 ppm hydrocarbons at idle and a little more at 2500).

 

What exactly does this screw do? I know its for the fuel, and Im thinking idle jet, but the idle jet shouldnt effect the main jets, and yet turning it gave me a lower score on the higher end as well.

 

Also, I dont see where it says what model of hitachi I have? where exactly is the plate the designates this?

 

 

Thanks

 

Alex

There's no plate that designates it - it's just stamped (in ink more or less) on the float bowl in the back.

 

That would be the idle mixture adjustment screw. 4 turns out is where it should be set initially before finer adjustement while running.

 

GD

Mines probably about 10 turns out to stay running well. Ugh.

I don't know if you experimented but if you turn that screw too much in the counterclockwise direction it is spring loaded and will shoot out and instantly turn your car off. I would be very careful with that adjustment and make sure that it is not near the point of no return because if it is it could vibrate loose while you are driving and that could be very dangerous.

4 turns out? Would that do the same thing on an 87 EA82 hitsloshie? Oh wait, there's a cap on that one. Nuts.