I have a 2008 KFX 50 that runs in idles fine but when you slam on the throttle all the way open it stalls you can feather the throttle till it’s wide open and it runs but if you go full throttle from a stand still it dies. I cleaned the carb multiple times I even swapped a carburetor from Kfx 90 and it ran fine. Thanks

 

If the main jet needle is adjustable, adjust it to give more fuel. If it isn't, get a new main jet. If that doesn't work, try a slightly bigger main jet, if you can get one.

 

How would I know what size main jet is in there now

 

Jets should have numbers stamped on them, on jets that small you may need a magnifying glass. Kawasaki manuals should have the information in them, and a Kawasaki dealer will be able to tell you what number is standard and what bigger jets are available.

 

I had the same problem on my 2019 kfx50.

Dealer turned up the idle a screw and it no longer has this issue. When cold engine, it will big down but not die if you go from idle to wot.