1969 25 Hp Johnson Fuel Problem High Speed

"I have a 25 HP Johnson which

"I have a 25 HP Johnson which has no high speed power, recently rebuilt powerhead with used block, reed value housing had a broken starting mounting support. Rebuilt carb, new fuel pump, fuel lines, fuel tank, new fuel.
Carb was apart twice and soaked, cleaned high speed jet.
Motor will not rev past half throttle, linkage will open carb correctly and if you close the choke about 2/3 the way when at full throttle you can get full power and will plane boat ( small 14ft), running lean my guess.
Fuel bulb is firm and if you pump it, no increase in power.
Carb gasket sealing, idles well.
1) can the high speed jet just be wrong size?
2) could have vaccumm leak?
checked hoses and plugged off, no improvement. Ran at full throttle with one spark wire off to see if one cyclinder was better than other, both have low power. Idea here was to check if crank seals were sealing.
Any ideas? Thanks
(next step will be unbolting from the boat in 50 ft of water..)"

"The fact that you can obtain

"The fact that you can obtain power by closing the choke somewhat indicates that you are overlooking something within the carburetor.

Did you install a new carburetor kit when you cleaned the carburetor. If not, it's possible that the thick round cork gasket is flawed that fits over the brass screw in venturi tube.

Also, if you did not manually clean the fixed high speed jet with a piece of solid steel wire, do so as solvent itself doesn't do the job as good as it should."

"Thanks Joe!
I did add a new

"Thanks Joe!
I did add a new carb kit. The high speed jet was physically removed and I can see the opening is not blocked. I wil again disassemble the carb and check for gasket probelms by the venturi tube.
Any comment on vaccum leaks or should I continue tolook at the carb system?
If I find nothing with venturi/high speed jet, should I consider replacing the carb? ( this is about the only thing not replaced)
Thanks again!"

"Hello Joe,
I disassembled t

"Hello Joe,
I disassembled the carb and found no gasket for the venturi seal! Apparently the new carb kit is for a slightly different model and the flaot bowl gasket is also different.. I added a gasket and now have full power.
Now at full throttle I have a (slight) pulsation, like a a intermitate fuel supply, Any ideas?
Again, new fuel pump & gasket, new carb kit, new carb to reed housing gasket, new fuel tank & fuel, new hose from pump to carb.

P.S. To what address to I send the case of beer and what kind do you like?"

"If a slight leak should exist

"If a slight leak should exist at either snap on fuel connecter, or anywhere else, that will allow the fuel pump to draw air which would result in that scenario.

Also, even though the high speed jet looks clear, should it be ever so slightly restricted, the same applies.

Check that the throttle butterfly does not travel past the full throttle setting (starts to close slightly).

I appreciate the beer offer but I quit drinking altogether quite a number of years ago. Doc said it was going to kill me, wife said she was going to leave me..... I didn't want to die lonely.<grin>"