kz650 stalling after warm up

Ok, check this out guys. '78 KZ650 D1 (SR). Starts no problem, runs great. After it's warmed up and I come to a stop it wants to stall so it gets kind of awkward to try to stop while bouncing the throttle to keep it from dying. Cleaned the carbs up really well and changed the gaskets. I recently noticed a little fuel weeping from some of the carb drain screws. Not enough to drip continually. The temperatures are now freezing up here in Connecticut so I've taken the battery inside and drained the fuel so I can't test it out until spring, but that means I've got time to order parts and tinker around indoors with the carbs. I have new drain screws and rubber washers since the old ones are beat up and might be the cause of the leak. Will install those, but any other suggestions would be great. Remember, it runs great, it's only the idle AFTER it warms up and has been driven that is the problem. Sounds like something is warn out and the heat expansion is making it loose?

I've got a video to help hear and see what I'm talking about:

Oh, and here's an image of the carb drip.

Hi Gcphoto - I too live in CT. And had similar problems towards the tail end of summer. Mine in the end, pointed to to the ignition system and specifically the coils. But I had issues with fuel, and carbs.

Without being in front of your bike. I would say you likely have a fuel issue either your drain screws are stripped or your fuel is leaking from the seal due to a bad float or tang adjustment - clear tube method will allow you to test your foats... that could be causing the drip ...

I have chased down a bunch of little things personally with my bike. Dirty carbs, crappy petcock lack of fuel filter, and faulty ignition system.

Hard to test because you need to test the coils when hot, and at times, it could even give you a false reading.

Are you still running points with mechanical advance? Were you able to confirm all the cyl are firing? What drove me to thinking mine was related to coils, was that 2 of my four cyl were cold when it would run rough... and those two were controlled by the same coil.

--- take a look at this tread I posted --- www.kzrider.com/forum/2-engine/595858-ru...-after-bike-gets-hot

Patton wrote:

Grnole wrote: ... the bike could no longer hold an idle, especially after it is warmed up....

Insufficient valve clearances can result in these symptoms.

Cool engine starts and runs okay until it warms up and then runs less okay and won't idle.

Good Fortune!

My 79' SR acts similar. I've found that when this happens, I have to reach under the tank and turn up the idle a bit.

But Patton has a point. Check your valve clearances.

It's possible it is running out of fuel after burning the fuel that was in the carb bowls. Make sure the screen in the tank (on the petcock) is clean and that there are no kinks or obstructions in the fuel line. Ed

Running rough after warm up is the CLASSIC symptom of a bad coil (guess how I learned that).

The other possibilities have been listed: valve clearance is one.

But fuel dripping off the carb makes me think one or more of the carbs needs it's float level adjusted using clear tube method. It's also possible there's a problem with the seal and the float valve so you have some continual flooding or overflow.

Thanks guys, there's a few good things for me to start with! Thanks so much and I'll let you know what happens. I'm going to start with valve clearance and float level. You guys are the best!

Hey GRnole I'm in Greenwich, right next door! Was just looking at your winterize post and coil thread. I knew nothing about bikes before I got one and I've learned a ton from the boards and youtube over the past couple of years but I still know nothing about electronics so I'm going to try the valves and carb float level before I look into the coils since I may as well be reading arabic when I see the world "ohm". reminds me too much of math.... eeeeeeew. :sick:

Just spent 20 minutes looking around for a clear tube tool and this is all I could find on z1.. www.z1enterprises.com/ItemDetails.aspx?i...asaki&item=57001-208 . It's the same thing depicted in my service manual but seems pretty expensive for what it is at $70. Someone mentioned ebay but I can't find anything. I've never done it before but read the instructions. Alternately I can just get a basic piece of clear tubing, unscrew the drain screw and pop on the clear tube?

No eBay APP ID and/or Cert ID defined in Kunena configuration

gcphoto wrote: Just spent 20 minutes looking around for a clear tube tool and this is all I could find on z1.. www.z1enterprises.com/ItemDetails.aspx?i...asaki&item=57001-208 . It's the same thing depicted in my service manual but seems pretty expensive for what it is at $70. Someone mentioned ebay but I can't find anything. I've never done it before but read the instructions. Alternately I can just get a basic piece of clear tubing, unscrew the drain screw and pop on the clear tube?

About $8

Z1E also has an aftermarket one for around $10. Ed

www.z1enterprises.com/ItemDetails.aspx?i...uzuki&item=ZSM01-208