KZ1000st Quick Carb Q

'79KZ1000st with the Mikuni VM26's

Bike was running pretty good, a tad lean a few weeks ago and on the advice of my mechanic, he suggested I bump up to 115 main's from the stock 110's due to pods/cored exhaust.

Since then, bike's been running really rich, bogs, you can smell fuel in the exhaust, plugs are dirty, etc.

I checked the coils/wires all ohm's are within spec. Spark looks healthy blue.

Petcock (vacuum) is rebuilt, works perfect, float levels are within spec. No more air leaks in the intake. Could moving to these 115's have affected how it's running? I thought those were more for midrange?

BTW I rebuilt the carbs and valves are within spec as well. Confusing.

Vm28s with 110s are stock for a '79st.
What is a tad lean?
What is cored?
What pilot jets?needle and position?

Ok plugs were more white than tan, stock pilots and needle settings. Suggestions?

Preface: I suck at carbs

That said, I would try going back to 110s, and raising the needle one clip.

Good luck

P.S. if the only change was the main jets, and it went down hill, probly not a good change.

Are you leaving it choked? And have you vacuum synced them after you rebuilt them?

main jets affect the running at 3/4 to full throttle. 1/4 to 3/4 throttle is affected by the needle clip position. the fuel air screws affect the o to 1/4 throttle position.

Bike starts on no choke, won't idle now.

I have an 80st, and on my carbs, VM28 pumpers, the needles only have 1 position. You can't adjust them. I don't know what they are like for carbs in question though.

I heard that before and it was suggested maybe the PO did a needle swap. From what I recall they were all in the middle notch. Thanks for everyone's suggestions BTW.

Cored exhaust - I took 12" out of the middle, removing the dented parts/acid damaged part. Still have the OEM plug on the end.

Not vacuum synced yet, only bench synced, waiting to get it running so I can drive it over to the shop for the vacuum sync (don't own the tool)

Bike was a basketcase and never came with an airbox, hence why I'm running pods.

Been thinking maybe my air screws need to be turned in a tad, going to try that after work today.

For you to be able to start it up with no choke suggests to me that you have an air restriction. And then for it to not idle suggests that it might be starving for air. Are the pods new? You might be onto something with the air mixture screws, but I'd suggest backing them out as opposed to turning them in. With how rich it sounds like its running, that'd be my bet.

I set my mix screw at 1 and a half turns ou from lightly seated have to do some final adjustments but she pulls like a bitch now and she only has a bench sync