Engine stops when throttle pulled

[12lanj01]

I got a '83 seca 400 and I just changed the oil and ran some seafoam through it to clean it out. However, when the bike starts up, the rpms will slowly fall until the engine stops. If I pull the throttle to get it to rev a bit, the engine will turn off. It is not until the engine is warm (which I keep the engine on by having the choke in for a few minutes) that I can pull the throttle and it revs fine.

I am thinking this is either a petcock issue (I have a vacuum; maybe the gas isnt going through the petcock as fast as it should be)

Perhaps a carb issue? (I have no idea how to clean the carbs)

Any thoughts? Thanks!

 

[16VGTIDave]

Are you using the cold start enricher? aka choke.

 

[12lanj01]

When I turn the choke on, it will rev at about 3000 rpm. So yes, I turn it on with the choke on, but how long should I leave the choke on? (I am leaving the choke on for about a minute)

 

[16VGTIDave]

As long as it takes to get some warmth in the engine. Chances are very good that if the bike hadn't been run in the past few months, the carbs will need to be cleaned.