Carb. idles way too fast won'y idle down

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.

From a cold start my sami idles really fast, but as I drive it and the engine warms up it will idle correctly. Is there a way to make it idle slower from a cold start?
what engine ? 1.3 L
carb or EFI? (94 was first year of efi, and many have been converted this old)
but the answer is the same , that is normal.
on car its a fast ilde cam on the carb.
in EFI its on the software and in the IAC thermal valve.

Hello

I know this is going to sound way to simple, but I would look for a air leak on the intake side. The reason I say this is that your engine runs because the computer feels it knows EVERYTHING about EVERYTHING.. Kind of like *********** N law. Well, when you get a vaccum leak, the computer doesnt know its stupid and raising the idle or POOR idle is one of the effects.

Now I am not at all saying this couldnt me something much more difficult, however VAC leaks are also pretty easy to check. Get yourself a can of SPRAY CARB CLEANER from your local parts store, some times gas stations have it too, wal-marts and places like that have it. Start your truck and SPRAY the CARB CLEANER around places that could have a VAC leak. Like hoses, the intake manifold gaskets and those kinds of things. If your engine suddenly runs REALLY ROUGH or even DIES when you spray a certian spot you know thats where your leak is.

I hope this helps you as much as it helped me

mcdevito75 here, The fast idle is needed when the engine is cold to make the air and fuel mixture rich to keep the engine running while cold, the carb. choke doew this with a bi-metalic spring in that balck round box on the side of the carb, a screw also hepls keep the choke closed until warm up, this screw can be adjusted tpo control how tight it holds the choke cloesed, here"s how to adjust this screw to slow fast idle speed, Locate on the carb, where the gas pedal connects, have a friend operate the gas pedal with the engine off, once you locate the linkage, you"ll also see 2 screws with springs around them, 1 is for fast idle the other for regular idle, you want the fast idle screw, notice this screw will lay against and Half moon shaped tab, while the other screw lays against a shaft, you need the screw that lays against the half moon shaped tab. Start the engine and step on the gas pedal slightly and relaease, at the screw that lays against this half moon, simply turn it counter clockwise or toward you just 1 2 or 3 turns very slowly, you'll hear the fast idle come down but you don"t want the fast idle to low, listen to the engine very carefully, slow it down just a bit, it should still race though but not out of control. Of course for a full carb, adjustment the shop should handle that., but this info will help.

Is the car idling faster than it has in the past when cold? The car is designed to idle a little faster than normal during warm up, to warm the engine quicker, and to keep it running. The fuel/air mix richens, (more fuel in the mix than normal), during start up conditions, and then as the engine warms, it should idle down to normal. Have you allowed it to continue its fast idle to see if it idles back down? Your post indicates that you turn it off and re-start to prompt the car to idle down. You have electronic fuel injection. The system adjusts to the prevalaint conditions to give you the perfect mix regardless of the condition it is presented with. It gathers input from a series of sensors that detect engine temp, outside temp, humidity and air pressure, to deliver the mix it needs. Often, when the mix is off, it is a result of a faulty sensor. This can be detected by running a fault code diagnostic check. You can have this performed for free at most national parts chains such as advance or auto zone. Other factors can cause an improper mix, such as dirty or clogged injectors, and/or a dirty air filter. Good Luck! I hope that you find this to be very helpful!

check and make sure air filter is ok, and there are no restrictions in hose to throttle body, check iac (idle air control.

Even with a rebuilt carb you have to make the adjustments. Check the choke adjustment and set the fast idle. If choke is to tight it will be hard to start and take a long time to idle down. The fast idle sounds like it is high also.

YOU NEED THAT THE CARBURATOR SHOKE BE RE ADJUST. IT HAS THE FUNCTION OF ELEVATE IDLE UNTIL MOTOR WARM AND THEN TURN IT TO THE REAL LEVEL. EXCESIVE IDDLE OR TIME MEAN CARBURATOR NEED BE SERVICED AND OR RE ADJUSTED

the throttle body gasket might be bad causing a vacuum leak.or possible bad idle air control solenoid.in the throttle body.

It sounds like an automatic choke system. Let it warm up for 5 minutes and then give it gas up to 2000rpm and release.