Bing 33 carb operation tips

[MiniHawg]

I am looking over a neglected MTD trail flite with an EC10 engine slapped on it. I believe it has a Bing 33 carb. Can anyone point me to information on adjustments and operation? I'm not familiar with the design (no float bowl at the bottom?), and not much of a mechanic to begin with. There is a button underneath that when pushed, gas flows down the fuel line. Is this a primer? Am I flooding the engine with it? It looks like the adjustment screws are very easy to adjust (if that's what the 2 flathead screws at the bottom are), any tips for adjustment at 1100 ft elevation? Any help would be appreciated!

I think I've got the choke lever figured out at least, it says start is in the up position haha!

 

[sparkwizard]

The little screw on top is idle speed.
The two big screws are mixture screws. The one closer to the engine is low speed mixture...like idle mixture.
The one closer to the air filter is your high speed mixture. What type problem are you trying to overcome?
Please keep this in mind. As a 2 cycle engine, it needs to be on the rich side for oiling purposes. You can get the engine to really scream by turning those screws clockwise, or lean, but the engine will get hot and seize from low oil. When it seems to work just fine and rev to the moon, back the screws out 1/4 to 1/2 turn just to be safe.
When you push the button, does gas run out onto the ground?

 

[MiniHawg]

No problems yet, just trying to understand what's what with this carb. I'll have to see if fuel runs to the ground when I push the button, it was already wet from trying to fill the fuel line with a funnel that was one size too big.

 

[sparkwizard]

If the button is in the middle of that diaphram on the bottom, it might be a primer. Not a primer bulb, like modern carbs but it might force the needle valve open to flood or prime the carb, but I'm only guessing.

 

[MiniHawg]

That's what I was thinking, it's the black plastic knob under the mixture screws in the top photo. I can feel it has a spring, and it doesn't spill fuel when pushed. Feels robust, and let's a good amount of fuel flow from the line.

 

[sparkwizard]

Think of that as a primer for use after sitting a while. As long as you're pushing it, you are letting fuel into your crankcase.
Try the choke first, pull about 3 times, press that for a couple seconds and pull some more.
Each engine is different, and old 2 strokes are certainly tempermental. You need to talk nice and listen to what they need or they won't do anything but make you cuss and break stuff. If it doesn't want to run, you can lock it in a dark space and maybe it will be more willing to run next weekend.