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It will never fly.

... you need positive fuel pressure to make that carb work, all the vacuum pump had to do was keep the float bowls fed with fuel. Fish carb originally had a solid copper fuel line connected to a very roughly 4psi mechanical fuel pump and pressure regulator for a reason, you have replaced that fuel line with a rubber tube and a tiny fuel filter pushed onto it, basically your fuel line can not handle any fuel pressure. The pulse pump on your bike only had to keep the fuel moving so it could spill into a float chamber that is not pressurized.
December 2nd 2020 :unsure: did you think I was kidding
 

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Discussion Starter · #243 ·
It's a carburetor, it needs a velocity stack, just like the original designer put on it:

... nothing is new under the sun. Carburetors have stacks.
and your intake tract is still way too long to perform well.
That's a Reece Fish, mine is a John Fish which has a lower profile and efficient "stack" cast in to it.
Having no venturi makes the whole thing a stack.
 

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Discussion Starter · #246 ·
This is what I am thinking.
Enclosing the top 2 3/4" of the tank, this will go 1/2 way down the intake flange and seal on a rubber ring.
I can then mount the air filter drawing air from the underside of the tank.
There is room to use my current air cleaner or I could use a modern style flat filter of a matching size.
I am not sure which would work better.
This is a rough drawing any thoughts are welcome.
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Should work but I don't think it will buy you much benefit, your injector type carburetor needs the fuel pressure regulated and you've taken up most of the steel fuel tank with air :unsure: not seeing much fuel tank or pump and regulator, what's the fuel capacity?

... and your long T shaped intakes are going to be soaking wet inside, any benefit you see from carburetor performance is going to be hampered by poor air flow, fuel vapour separation and reversing air flow.
 

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Discussion Starter · #248 ·
Should work but I don't think it will buy you much benefit, your injector type carburetor needs the fuel pressure regulated and you've taken up most of the steel fuel tank with air :unsure: not seeing much fuel tank or pump and regulator, what's the fuel capacity?

... and your long T shaped intakes are going to be soaking wet inside, any benefit you see from carburetor performance is going to be hampered by poor air flow, fuel vapor separation and reversing air flow.
Fuel pressure is just taken care of by a low pressure electric pump 2-4psi.
The design of the TB/carb has vented a float bowl and as long as there is adequate fuel to cover the metering it will run correctly exact fuel level is not critical like a normal carb.
As for fuel dropping from atomization and pooling, it seems to have been made a non issue after fitting the balance tube.
But fuel dropping from suspension is most likely to occur at WOT with minimal vacuum at even on the dyno test I did, because the metering was just way out bottom end I needed to mal adjust it at the time and the throttle was only 85-90% open at full throttle despite the ok hp for a first test.
Bottom line, it is opening full throttle now but It is not dialed in so I won't know till I get this tank done and back to the dyno.
Fuel capacity is not measured yet but around 12lts.
 

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Discussion Starter · #250 ·
Tank sealed enough to check volume now.
Cut out the shape around the old filler and welded in a plate.
I have left the seat recess in the tank open still for panel beating access, but before I fit the new fuel filler bung I can put it on its end and fill it check volume and check for leaks.
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Discussion Starter · #252 ·
I silver soldered the new filler bung into the tank I am making.
The bung is stainless steel and the tank is mild steel.
I am using 2% silver rod from the plumbing supplies.
I used a propane torch to tin around the tank opening and I planned to sweat the stainless part on after adding flux.
But my propane torch was not heating the stainless quick enough.
So after some experimenting I used the Tig torch set to AC 35amps with flux and gas, and it worked.
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