24mm bored 3-circuit carb for the gx390 & 420/440/460 clones

[raydhd]

Originally Posted by Shepard

It rides on the backside of the main jet and draws its gas off of the main jet gas supply. The performance of this carburetor is outstanding after you get it adjustable. Not knowing if there are replacement jets are available for this circuit I never even looked at changing it cause it works so well the way it is.

Shepard's EXP-S on my 460 works like fuel injection. Mine has the choke removed and starts cold without feathering or pumping the throttle. It also goes from off idle to my 5600 rpm red line without any flat spots. I can jump on it at any RPM and get instant throttle response. In truth I don't know if he bored out my Ebay sourced main jet or not. I installed it after it's arrival from Owego as shipped. I did turn the idle mixture screw back to 1 turn and had to back off the throttle plate idle screw back several turns. Don't know if Shepard put elves inside or what but I haven't did a thing to it all season.

[Rooster59]

If Shep played with it no wonder it works like that. I might remove the choke on mine but I had better wait until winter to make that decision.

[raydhd]

If you are lean already removing the choke will make the the situation worse because of the increased air flow.

[Shepard]

Is the float and needle operating properly? The fluid could be to low in the bowl for the carb to pull the gas in. That can make for a lean condition.

[Rooster59]

It has been lean with the stock carb and the modified carb with adj pilot and main jets. It could be a float issue but it has been this way with both carbs as well as stock and modified filter setups.

It pops on a chopped throttle way less with the current setup versus completely stock. That leads me to believe it is richer now but still not enough to give a slight tan color to the plug.