Enrichment Circuit clogged?

78 KZ650, stock air box, stock carbs, stock exhaust. Wondering if anyone can help me decide which direction to take. My problem is the engine is difficult to start when cold (sitting for 2-3 days or more below 60F). Need to kick 30-40 times to start with full choke on. The longer it sits, the more kicking required to start the engine. After it starts, need to eliminate the choke within 10-15 seconds or will start sputtering. Most KZ's I've seen require a bit of choke for a few minutes but this one requires full choke to start then shut off choke rather quickly which makes me think it's running a bit rich.

I cleaned the carbs last year but they were not really that dirty and did not resolve the issue. I noticed if I partially blocked the air filter intake with a rag, the cold engine would start rather quickly with electric starter which it would never do in the past so I'm onto something. Once the engine is warm, it starts on first push of the starter. It does have a slight hesitation around 2K RPM and figure that may have something to do with the cold starting problem. Plugs are good, valve lash is good, electronic ignition good, carbs sync last year after carb rebuild.

Any ideas on the carbs or am I going in the wrong direction?

If not reading already you should be tuned to the thread, not running on two cylinders that's going now. Do these same checks, as it sounds like you have a voltage problem.

Normal to some extent. If the engine is old and worn they are tough to start cold. KZ650 was never a great starter after sitting. This has been a problem since they were new. Way back when mine was nearly new, well it was 3 yrs old with 30,000 miles I tried to get around this problem by swapping the intake boots so the nipples were pointing upwards so I could spray a little gas in to help. This was not a great fix.
I ride all year around on a KZ650 for the last 33 yrs and have got used to this model. They will be hard to start cold after sitting, that's a given. What I do if I haven't ridden for a few days or more is start the bike in the warm of day the day before I want to ride, then come the next day if it's cold out the bike will start. Also turn off the headlight, turn the fuel lever to prime, yes gas evaporates out of the carbs some in as little as 24hrs, then kickstart, don't bother electric, it will never fire. The older they get, less compression to suck in fuel the worse it gets on an already marginal to say the least starting system.

Ron
It's a bit of a relief that I'm not the only one with difficult cold starts. I agree the KZ650 were never great cold starters and I do turn off the headlight, petcock prime, full choke and kick.

What I am pondering is why I can partially block the air intake and use the electric starter which will start the engine within 4-8 seconds. I'm feeling like there is something wrong with the choke circuit. Would blocking the air intake increase the suction from the enrichment circuit and or the pilot jets?

Has anyone else ever tried this starting technique with a cold engine after sitting a few days?