Overnight cold start issue

[Vdriveboater]

This problem persists on my '94, from the time I bought the bike and after I went through the carbs. Bike starts immediately when warm or hot. After sitting overnight on a cold start, it cranks and cranks and cranks and after 20+ seconds of cranking, it finally burbles, sputters (sounds like one or two cylinders firing), and slowly the rpms come up. I've tried playing with different choke settings (functional) and I turn up the idle screw about 1/4 turn clockwise to help. I've read about the fuel pump on these, that they keep the bowls full. But it's impossible that the bowls are running out of fuel in 15 hours, so I can't see that as the problem. There are no fuel leaks (externally) and no gas odors. It runs beautifully once warm, and fires up as soon as the starter is engaged. I've never owned a bike that had this kind of issue. My '01 Kaw ZRX1200R had a similar carb set up and cold starting was never an issue.

[buzzcut]

pilot screws too lean????

[Vdriveboater]

I tried that too -- 3+ turns and 1 turn, no difference. I just started it today after it had been sitting for over two weeks, and it was a bear to get going. If it was spark related I should be having issues when warm, so it's got to be something fuel related. It's a real head scratcher.

[GrandpaDenny]

1. Choke should be full on when starting cold.
2. Did you check the choke plunger clearance?
3. Check for vacuum leaks.

[Vdriveboater]

1. Choke should be full on when starting cold.
2. Did you check the choke plunger clearance?
3. Check for vacuum leaks.

1. Yes this is what I'm doing, full choke
2. Not familiar with "choke plunger clearance"
3. I assumed that any significant vacuum leak would affect performance cold and warm, no?

[GrandpaDenny]

1. Yes this is what I'm doing, full choke
2. Not familiar with "choke plunger clearance"
3. I assumed that any significant vacuum leak would affect performance cold and warm, no?

There is a measurement of how much the choke linkage moves before it pulls out the enrichment plunger on the left side of the carbs. Do you have a service manual? If not, there is a link to the manual in my .sig. Look in "fuel system". Kaw doesn't call it a "choke" it's an "enrichment system" - the difference being a choke restricts air flow to enrich the mixture, whereas Kaw's enrichment system adds fuel.

A big vacuum leak will cause all kinds of problems. A small vacuum leak will drive you crazy. I still have some kind of air leak somewhere on Gertrude, gotta be, as I'm getting snarling and popping on deceleration and sometimes she's hard to start cold.

[GrandpaDenny]

sometimes she's hard to start cold.

I need to double-check the choke plunger adjustment myself. It "appears" to be OK, but as I mentioned she's hard to start cold sometimes. I did discover that I can pull the plunger out by hand and that usually helps. Simple cable adjustment. I need to pop the cable off and lube it anyway - periodic maintenance.