Starting problem!! HELP!!!! SOO CLOSE!!!

[Cprisco13]

The bike hasnt started in 30 years and after doing carbs and spark plugs I am trying to start her up! With the choke on when i hit the ignition it starts to fire up and sounds like its actually running until i let go of the ignition button! What does that mean! I literally feel like it is running but as soon as i let go of the ignition it just stops! Please help, Thanks!

 

[madmtnmotors]

>Gas in gas tank?
>Battery fully charged?
>Have you checked static timing?
>Who rebuilt the carbs? How do you know they were done right?
>Plug wires crossed?
>Points wires to coils crossed?
>Kill switch in "run" position?
>What bike?
>What year?
>After "doing carbs" did you check/clean the fuel tank and fuel valve?
>Later models (77/78K, 76 thru 78 F and "A" models) have a fuel filter in the tank. If you have a later model, did you check the in tank filter?

 

[Cprisco13]

>Gas in gas tank?
>Battery fully charged?
>Have you checked static timing?
>Who rebuilt the carbs? How do you know they were done right?
>Plug wires crossed?
>Points wires to coils crossed?
>Kill switch in "run" position?
>What bike?
>What year?
>After "doing carbs" did you check/clean the fuel tank and fuel valve?
>Later models (77/78K, 76 thru 78 F and "A" models) have a fuel filter in the tank. If you have a later model, did you check the in tank filter?

1972 CB750. Where exactly is the kill switch? if its the red switch on the throttle control then yes it is on "ON" not OFF. gas in tank, wires not crossed, I cleaned the carbs, the only thing I'm not sure about are the screws(idle etc.) and the jets(how many times to turn them). I'm not sure if that should cause what is happening. I cleaned out tank and installed new petcock.

 

[Cprisco13]

>Gas in gas tank?
>Battery fully charged?
>Have you checked static timing?
>Who rebuilt the carbs? How do you know they were done right?
>Plug wires crossed?
>Points wires to coils crossed?
>Kill switch in "run" position?
>What bike?
>What year?
>After "doing carbs" did you check/clean the fuel tank and fuel valve?
>Later models (77/78K, 76 thru 78 F and "A" models) have a fuel filter in the tank. If you have a later model, did you check the in tank filter?

1972 CB750. Where exactly is the kill switch? if its the red switch on the throttle control then yes it is on "ON" not OFF. gas in tank, wires not crossed, I cleaned the carbs, the only thing I'm not sure about are the screws(idle etc.) and the jets(how many times to turn them). I'm not sure if that should cause what is happening. I cleaned out tank and installed new petcock.

 

[madmtnmotors]

These are pretty basic machines. Barring any major mechanical failure, all these motors need is properly metered fuel and correctly timed spark. Run through the 3000 mile tune up procedures paying particular attention to the ignition timing, since that is the easiest to get right (when compared to carburation).


Ignition timing can also be the easiest to get wrong!