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Should I be able to blow through this inlet? It's the fuel inlet, not the primer bulb one.

Depends. Are you holding the metering lever down to open needle valve? now if you got the crab disassemble then yes.

I don’t think so, if you still have the diaphragm mounted on the backside, under your finger.

StarTech said:

Depends. Are you holding the metering lever down to open needle valve? now if you got the crab disassemble then yes.

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Basically the fuel in side is open when you got the fuel pump cover off so air or fuel should flow through to that side and the fuel cross flows thru the metering needle valve to diaphragm side. The engine vacuum opens the metering needle valve by depressing the metering lever.

One the main problems with these carbs is that the metering diaphragm get stiff and can't open the metering needle valve

StarTech said:

Depends. Are you holding the metering lever down to open needle valve? now if you got the crab disassemble then yes.

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Doesn't even know seem to be working. Gonna watch some YouTube vids on this carb ...

Rivets said:

I don’t think so, if you still have the diaphragm mounted on the backside, under your finger.

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So just pushing air into the carb should NOT push fuel in as only suction through the diaphragm from the engine pulls fuel in?

StarTech said:

Basically the fuel in side is open when you got the fuel pump cover off so air or fuel should flow through to that side and the fuel cross flows thru the metering needle valve to diaphragm side. The engine vacuum opens the metering needle valve by depressing the metering lever.

One the main problems with these carbs is that the metering diaphragm get stiff and can't open the metering needle valve

Click to expand...

So what does this say about new carb being able to push fuel into the carb? It's it just going as far as the diaphragm? Where is this a "metering valve"

Fuel is not push into the carburetor it is pulled into via engine vacuum moving the metering metering which opens the meterneedle valve which operate the fuel pump side of the carburetor.

The following cover Zama but theory cover all diaphragm type 2 cycle carbs.

StarTech said:

Fuel is not push into the carburetor it is pulled into via engine vacuum moving the metering metering which opens the meterneedle valve which operate the fuel pump side of the carburetor.

The following cover Zama but theory cover all diaphragm type 2 cycle carbs.

Carburetor Systems And Operations

Disassembly & Servicing (Types C1U, C1Q/M, C2, C3, C3A/M)

Troubleshooting Charts

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Cool thanks. I'll look it over. What's "zama"? They make a lot of carbs we use?

“Zama” is a carb manufacturing company. Here’s Walbro’s guide. http://www.baja5b.lv/wp-content/uploads/teh-info/Walbro Carburetor Theory.pdf

Absolute best explanation in the operation of these. This guy really went above and beyond with this one

So I've got the old on there with the new one's diaphragm as the new one wouldn't start after a while anyway and as you can see it has that big yellow choke lever which is't compatible with the air filter cover without a Pita.

Anyway the new diaphragm got it going but can't keep it going. Dies under throttle and can only stay running if I play with the choke and throttle.

The shown adjustment tool that came with this new carb doesn't fit these moon looking type screws. Any tricks to turn these?

The tool that you got is the 21 spline tool. What you need is the single D tool.

HIPA 2 cycle carb adjustment tool set