1979 KZ 650 carbs

I have a 79 KZ 650 Sr my number 2 carb keeps sticking as in the bike will start on choke number 2 cylinder isn’t getting gas. If I whack the number 2 carb with a wrench work the choke and throttle it will start working and the bike will run fantastic all day. Let it sit for a day or two it’s the same dance to get it running again. This bike has the pumper carb #2. It was setting for 20 years I cleaned the carbs and fixed it up over the winter. Is this a stuck closed float needle? Or could it be something else

Sounds like the pilot circuit in the carbs need cleaning.

Could be but why would it work if I smack it with a wrench? I don’t think there are moving parts in the pilot circuit maybe loose dirt? Also when it does this the bike will only run on choke but not at high rpm like it’s on choke it will stall if you give it gas smack carb #2 for a bit and it runs properly

Definitely sounds like the needle is sticking. When I rebuild carbs I like to polish the inside of the seat with some brasso and a q-tip in a drill. Smooth surface for both the needle to seat and smooth sides so the needle does not get hung up.

Thanks that’s what I figured. I did clean them with q tips but that polishing idea is awesome I will add that to my bag tricks. if it doesn’t clear up with use I will take off the carbs and give it a shot

Running only on choke is classic symptom of clogged / dirty pilot circuit. Polishing the seat is a good idea and STOP hitting it was anything.

baldy110 wrote: Running only on choke is classic symptom of clogged / dirty pilot circuit. Polishing the seat is a good idea and STOP hitting it was anything.

True but I think he was stating that it only ran with the choke on until he taps the bowl to unstick the float/needle. After that it runs fine.

Yep only after tapping on the carb aggressively so something mechanical is stuck. Then it runs good until it sets for awhile.

Ok, I tried good luck

If you had read my original post you would see I had the carbs apart and cleaned them over the winter. I don’t think my pilot jets or air passages have plugged up in the 6 days that the carbs have been back on the bike. But I guess it could be possible. I also replied if the issue continues I will remove the carbs and go through them again.

Did you take the carbs fully apart and soak all the hard parts in carb dip? Replace all the soft parts like O-rings and gaskets? Perform a vacuum sync after getting the bike up and running?

Yes I did