Running problem, need ideas....

[rev79xs11]

Well, i decided to put my 11 back on the road. I left it sit last year because it ran bad and i couldn't afford to fix it. When i tried to statr it it had a dead cyl. I checked the plugs-ok but i found 1 really wet one. I suspected the carb might be at fault but was wrong. As it turned out it was the diaphram in the vacuum valve. It had severed and was allowing fuel to be pulled into that cylinder. I rebuilt the vacuum valve and all is well...right....nope I still had a problem but not a dead cyl, it just would not run low rpm. I pulled the carbs, cleaned them and verified all passage were clear. I put new needle/seat, bowl gaskets and changes to 45 pilots while apart. Fixed!....wrong.
Heres the current issue. It starts with choke on full and you can drop choke to half and then off. It will idle BUT anytime you gently turn the throttle it pukes, studders and so on. If you get deep into the throttle it runs great so i think the maind, pilots and diaphrams are working. Even with the low rpm problem i can tell the difference with the new pilots.....strong! Heres the kicker, after it runs about 5 minutes it gets better, and better and better. I'm thinking thermal vacuum leak but can't seem to find one. Any ideas?

[DGXSER]

Everything your pointing to says your enrichment jets in the float bowls may be plugged.

There are small jets in the float bowls that supply the enrichment circuit (choke). Adding choke makes it run stronger, says your running lean. Warming up runs better, says it is lean when cold. Put the two together and it sounds like you have a lean condition when cold. Plugged enrichment circuit.

[bikerphil]

Try some Seafoam.

[TopCatGr58]

Hey Ron,

A few questions: Where did you get the Pilots from, genuine Mikuni from bike shop, or where?? There are 2 styles of pilots that will fit into the carbs, one is WRONG..the VM series...the BS series are the correct ones.

Secondly, you cleaned the carbs....did you REMOVE the pilot jet SCREWS from the top front of the carbs, and ensure that the tips were not broken off!?

Thirdly, the 79SF carbs should have had the metal screw caps for the Pilot jet towers inside the bowl area, just making sure those were replaced, still there...the towers capped off!?

Have you checked and verified no vacuum leaks from both the intake boots to engine connection as well as the synch ports rubber caps...they harden and can be "in place" but be loose..spin easily and leak!

T.C.