Kawasaki FC420V problems

Greetings, I read your question and I think Reliable-Store can help you in this. Here's the site link -

https://www.reliable-store.com/products/kawasaki-fc290v-fc400v-fc401v-fc420v-fc540v-ohv-4-stroke-air-cooled-gasoline-engine-service-repair-workshop-manual-download

bad starter or bad ignition switch. try putting it in gear and rock it back and forth, if it starts then you have a dead spot in the starter.

you can tell by bypassing the solenoid with a jumper wire, just touch it from one terminal to the other and if starter jumps you know it is good but only jump for a second do not connect only touch.

Don't worry I'm sure you will get the solution of your problem, just check the link I attach.
Best Manuals

Spark Plug Gap Specs show .028 to .031
I set mine at .030 Hope this will help

if your lucks good.
try this. drain your oil. gas may have seep by piston.
and the crank case has to much liquid in it. "BINGO"
might be your lucky day !!!

remove the main jet in the carby and clean out as it has gunk in it preventing the fuel to pass up to the venturi

I have the exact same problem on a JD175 with the same engine--gas spewing out of a hole above where the fuel line connects on the back of the carburetor housing. There's a similar hole on the opposite (front) side of the housing. I'm told there are factory-installed plugs in both holes and the whole carburetor assemble will need to be replaced. Please post if you discover something different!

It sounds like your valves may need to be adjusted...
if they are too lose or worn they won't seat properly and when the engine fires it blows back through the intake valve.
pull the cover and see if the rockers are loose... it only takes one to give you a headache.

It could be the float chamber on the carb/s not sealing off with the petrol valve and filling up the air inlet and then draining down to the crank case.