honda spree dies at full throttle.

[cyclebuster]

It will idle fine forever. 1/4 throttle no problem. snap rev its perfect, revs up great. Ride it once, or hold it anywhere over 1/4 throttle it dies like a switch was thrown. here is what i did to it. and no change except it runs great other wise now. ran poor but died before.. now runs great and dies. 3100 miles. looks like new.
1 New battery {irrelevant}
2 new spark plug
3 new fuel line
4 cleaned the carb... it didnt need it. blew air and cleaner through all passages
5 put needle clip all the way down.
6 put AC voltmeter on coil wires, its not losing power. Ac voltage the same before and after it starts to die
7 tried different coil
8 took pipe off and banged on it, nothing in it, not to heavy, and it sounds right at idle. pop pop pop. ran it with the pipe off for a few seconds, does the same thing.
9 adjusted float up and down.
10 took carb off a half dozen times. no dirt, corrosion or fuel crud anywhere polished emulsion tube shiny outside, all holes clean, jets clean. cleaned and verified idle jet is open.
11 verified oil flow from pump
12 checked operation of choke motor. has continuity, and gets hot. i am sure its working fine.
13. took petcock off and verified its clean inside and has excellent flow
14. bypassed petcock and ran on auxilary tank.
15 changed gas with new.

I am ready for step 16 which is... kick junk spree out the back of pickup at 70.

I have owned and sold and parted several dozen sprees. I am sure someone here has bought a used spree part from me, if they shop on ebay. Does anyone have any ideas? I dont need any smart remarks, if you dont know i dont want to hear it.
it seems to have good compression, starts on half a kick, which a tired engine will not do, and idles perfect, another thing a tired engine will not do. I made a half cup with my hand over the intake, and it has good suction. If you plug the carb, when its dieing, it will rev right back up, so its got to be fuel. *?

[Bear45-70]

Is the air box on the engine and is the air filter in place. If not it will do what you describe, no run above 1/4 if that much.

[cyclebuster]

air box, intake, filter correct and installed.

[Bear45-70]

Where is the idle mixture screw set? Check for air leaks on the intake.

[cyclebuster]

well the idle air screw is set at 1 7/8s but idles better at 2 so i left it there.

[Trafficjamz]

Take the pipe off and look for carbon buildup on the exhaust port itself.

Sometimes the carbon clogs the port not the pipe..

[cyclebuster]

true but carbon does not come and go

[facechicken]

I realize this is an older thread, but i am having the same exact problem......did you find an answer for it?