2014 25hp bogging down problem

[Southernboy1015]

Need some advice here. My 2014 25hp 4 stroke bogs down at 1/2-3/4 throttle. It starts up fine, 2nd or 3rd pull. I have cleaned the fuel filter, the carberator 3 times very throughly, spark plus are good, and the fuel pump seems to be functioning properly. I also changed the tank and lines, only use premium non ethanol gas with seafoam mixed in so the gas is good. I am out of ideas of what can be the problem. I believe it is a fuel problem, seems to not be getting enough fuel at the top end. Can someone please help?!?

[pstephens46]

Has it been sitting for a period of time?

Have you (or someone) tried pumping the primer
ball when the issue is occurring?

[99yam40]

being carbed only way I can think of to drop /limit RPM would be to jack with the timing or limit fuel.
might check to see what the timing is doing when it acts up

Just thought about dropping a cylinder due to spark or fuel
Too much or too little can keep a cylinder from burning properly
Do you have any indicators that the motor is having over heat of oil problems ?
what RPM does it get to when this happens?

[Southernboy1015]

It did sit for a couple of months before I had used it again but have cleaned it multiple times to try to fix it. Yea, I’ve tried pumping the primer, it stays firm the whole time when revving and at an idle. It doesn’t over heat and it doesn’t have any oil issues. I don’t know at what rpm is starts acting up, it doesn’t have a gauge.

[TownsendsFJR1300]

When you cleaned the carb, did you actually remove ALL the jets? Not just a spritz of carb cleaner in the hole.

It's imperative to have them out and be able to actually see light thru all the small orifices..

Does the engine run at WOT or stay at the 2/3's throttle? (Throttle wide open).

[Southernboy1015]

Yea I always take them out to clean them. This time I soaked them both in a chem dip, they look brand new. I think I may have found the problem but I have to wait until the part comes in. I am missing the rubber cap that goes in the chamber with the small jet. Going to try that then will get a new needle valve if that doesn’t work.

[99yam40]

yep,

The purpose of that plug is to keep the pilot jet from sucking directly out of the bowl.
all fuel is suppose to be pulled thru the main jet.,
even the pilot jets supply (there is a passage between them)
during low RPM the missing plug is no problem, but at high RPM the motor is getting too much fuel thru the pilot and main jet combined with the plug missing

[rodbolt17]

partially correct.
the idle circuit is used throught the RPM range.
ALL fuel burned MUST pass throughthe main jet.
with the plug out the hole tat connects the main and pilot holes effectively bypasses the main jet.
either way it runs pig rich at higher speeds.

[Southernboy1015]

yes that was the problem. its fixed. thanks everyone for the help. much appreciated.

[rodbolt17]

self inflicted wound glad it worked out.

[99yam40]

He discarded the plug or someone before him.
I found the plugs in some carbs fell out before, but they stay in the bowl