Engine wont idle, fumes very, very rich. new plugs every second week. i was told float levels to high.

no year told, nor when it last run perfect not told
same answer for 100 years on any otto cycle gas engine made car or motorcycle or scooter.
same., and drives fast too, full power work but idle fails.

well , idle is too rich, as are all carbs this old and never serviced.
when it stalls i bet spark tip is wet with fuel or carbon fouled.

or bad fuel. or caused by bad fuel endless for 100years
ive cleaned like 1000s of carbs in 50+ years. endless. me.
it's only a 150cc engine, and tiny carb. my CB750s old and new.
both had 4 carbs and are tricky and must be synchronized
but your's is a pussyycatt. 1 carb small
causes all.
the float needle is bad causing too high float level.
the jets are bad or wrong or dirty. there may be 2 jets one is idle and bad. but most time not 2, just 1 jet and 1 needle.
the needle can be bad , most are this old and bottom of needle is idle section OF NEEDLE and all worn out and now super rich at idLE SPEED
the air paths inside the body of carb must not be clogged
all tiny air paths. checked and cleaned fully.
that is all I can think off off hand.
my guess is bike is super old.
is bike real honda or this trashy china clones of 80 honda.
no year told nor photo of it so we can ahhhh that BIKE,
THE TANK VIEW IS OMG EASY TO ID.

NOT TOLD , FAILS IDLE HOT AND COLD ENGINE BOTH.
Using throttle grip hold RPM up a tad to get it hot first and see if idle reall fails hot.
first 150cc bike owned ever,?yes
the learn this.
we start with mild choke cold and back it off bit by bit until warm.
the chock has a fast idle features that must not be broken.
back it off slowly for 5 mins. then idle works
some have idle mixture screw on the side or is fast cold idle screw.
the cables are not for idle. ever and are set loose side
a stop screw idle and maybe mixtures idle. tool
depends on year not told if honda mikuni made.

Turn it all the way in, then back it out 1 3/4 turns. This should be a good place to start with.

Check the float it maybe set too high... the gas falling into the float isn't running long enough before the float shuts her down.. Also check that the line from the fuel tank is clear and not full of kinks. Then set the low idle and high idle needle valves on the carb... call manufacturer or local much to get the screw turns...make sure the rubber seal between the engine and the air is not sucking in air. ... it's usually like a mini pipe.

adjust the float level to the correct height

if the carburetor keeps flooding out, the float could be stuck in the up position. tap lightly on & around fuel reservoir to free. depending on age of carburetor, you might need to put in a carburetor kit.

Yes, the floats may be causing the fuel level in the carb. to be too high. The black plugs indicate running too rich. Clean the plugs and check the fuel level.

Float height should not be overly critical.. Why was the float level changed just to rejet? gas overflowing sounds like a stuck Float.

runs rich on high speed or hunts with black smoke
and fine on idle Lets understand it this way whenever there is black smoke that means there is not proper combustion in the cylender head means un burned fuel means less power which is either fuel is not pure due to dust particals or there is not proper current through the spark plug that means fuel is not burning properly and resulting in to smoke in the exoust if you have checked the fuel already then check for the current coil for proper currrent through a wiring diagrame which can possibly make you check up to the inverter level to see if your inver is malfunctioning if its ok then check the air fuel mix screw on the carburator to check that the full oxygen supply is going in the carb for proper combustion try adjusting the air fuel ratio on high speed or on load even than the problem persists check if your spark plug is wet after a brief running if it is dry thsn its fine if it covered and wet with engine oil that means engine oil is comming in to the cumbustion chamber and burning with thr fuel and resulting in to smoke for that matter you will have to check your piston rings
if your

Black smoke means the fuel mix is too rich. Assuming you have not changed the jetting, I would say the float level is set too high. The only other possibility would be a main jet that has come loose.

Well the most problems are in the carbys {running to rich or to week} and with 2 carbys you must have them in tune with each other by about 98%.
and with a plug getting wet your float level is to high so when your going the fuel is getting to much in that cylinder and putting out a strong mixture and the other one to weak and you could also have a gasket on the intake sucking air or the exhaust has a bad flang gasket or a small pin hole in it some where
WHEN idleing put your hand over the tailpipe and stop the exhaust and see if you can hear a small blow if so fix it and the same the other side.
AS ITS ALL TO DO WITH HEAT AND INCORRECT MIXTURE so L/H is to much fuel,,,R/H cyl is running almost correct but wants tuning.
Have a goodday RON