I have a 1980 Honda 750k. I recently purchased it and it wouldnt hold an idle at all. would just die if you wasnt giving it gas. I had the carbs tore down checked and rebuilt but I am still having the same issue. Ther is no engine noise at all. bike runs ok if your giving it gas but if you let off the gas at all it dies instantly. any ideas would help alot. Thank you

Check for vacume leak including intake. Spray some carb cleaner around intake and vacume hoses and listen for engine rpm to change.

Carb problems. Sounds like the choke is not working.

Sounds like you have a float sticking in your carburetor, is this a single carb or a duel carb? , also gas can go stale and your bike will run like **** if it also has been subjected to tank condensation and water in your gas, that also maybe your problem, I would drain the tank and drain the carb or carbs, and start off with fresh gas and would use 89 octane or better, also pickup some StarTron Enzyme gas treatment, it will stabilize your gas for up to 2 years, and remove the ethanol from your gas, that is a bad for your motor, try it you will never go without it. Good luck, Rick.

water in any plugs will cause this also

Try pulling the carbs, and then the jets. Give the jets a good cleaning, should be fine after. Also, run stay bill in your gas for no future problems.

sounds like your carbs need balancing.

my 2001 just had that problem. Take off your air cleaner and look in the carb. There is a plastic venturi there that sticks. it will free up with your finger

i guess it has carbs on that year, which means
1.your main jet is blocked or
2. fuel filter is clogged,
3. fuel pump worn out
4.blocked fuel line
you simply have just enough gas to idle but when you demand more there just is not enough,

have 04 polaris predator 500 doing the same thing, when giving full throttle it seems to be hitting a limiter a couple of 1000 rpm below full rpm, but will only start with air box disconnected from carby and spitting gas out, might be buggered T.P.S unit have bought new Keihin Flat CR carby with T.P.S on it so to replace one on thumb throttle as it has taken some knocks ( should be able to test T.P.S with volt meter when pushing the throttle), a cdi unit and coil will see how that goes.

Carbs gummed up. Need a serious cleaning or a full ruubers replacement/rebuild kit. Gas turns to gummy when left stting in the fuel bowls.

Use a couple of cans of Sea Foam.. best stuff in the world.