1977 KZ650 final tune

I have a 1977 KZ650 that I have done a bunch of work to. The reason I have done all the work is because it had a hard time starting when it was cold. Know that the work is done it started right up.

I have done the following to the bike so far.
Valva adjustment, cleaned the carbs, new plugs and a Dyna Electronic ignition.

Here is what is happening.
I start the bike with the choke on and it starts and revs to about 4000rpm. I adjust the choke to bring the idle down and it works. The bike runs for a short while at the adjusted choked idle and then revs up again to about 3000rpm. Every time I adjusted the choke to compinsate for the increase in rpm's it would do it again.

Once the bike gets warm. I am not able to turn the throttle with out it wanting to choke out. I have to feather the gas to get it to go. Not smooth at all.

Once I do get the motor to revs up and let go of the throttle the bike wants to keep the rpms even thow the throttle body/carburator has returned to its idle postion. I hope that made since.

I was able to ride the bike down the street and when I pulled in the clutch to shift gears it would keep the rpms up and not relax during the shift. The only way I could get it to go back down was to hit the brakes and it would force the motor to lower the idle.

Dont forget that when I turn the throttle it has no problem returning to the idle position. But the idle stays high.

So it comes down to this:
Why wont it run smoothly and not spit and sputter?

Why is the motor holding the rpm's even though the carb returns to its idle position?

Let me know if you need more info. I will do my best. Thanks for any feed back or ideas. Greatly apprecitate.

Dave, there is a relitivly recent post on cleaning the pilot ckt on Vm's read it, It's Good... The KZ650 has a history for cold start issues, and from your' description you're suffering from muliple probs. In my experiance, they were jetted lean (for emissions) from the begining.Then, the head is VERY efficent in disipating heat. Thus, you fire up bike, it brings up head temp, & revs climb. (stage 1) you mess w/ choke...( a misnomer, more truly an "enrichening" circuit.and things stabilize... If you attempt to ride at this point, air flow drops head temp & yer back to "cold bike" symptoms. Next, Old intake rubbers crack & leak. A quick check is spraying wd-40 or its ilk on 'em at idle & listening for revs picking up.Next, pull points cover, & attach timing light. rev & watch advance progression. Timing should advance &retard smoothly to base settings. if no vac. leaks & timing is good, "It's back to carb land." I believe all '77 650's ran VM 24's w/15 pilots. try 17.5 s after double checking carb passages at 1, intake throat pilot air passage, 2, air screw orifice,3,pilot jet mound,4,mixture passage at slide leading edge, &4 mixture screw passage/screw (if applicable) # (there were/are at least 3 different carbs avail. thse w/ air screws, fuel mix screws, & both) It took me years to get mine to it's present state, & on cold days It still requires a couple minuites of warm up before it's truly happy. luck g

Just to double confirm whats said.

Sounds like you have an air leak for sure, and also your carb pilot systems may still have blockage.

When cleaning carbs: Use the straw included with spray can type carb cleaners, and taper the end of it so that it fits right into the pilot jet.

Then (with glasses on), VISUALLY VERIFY that the carb cleaner is coming through all the small passage holes in the throat of the carburetor when you spray the cleaner.

It should be nice clean streams that all look the same from carb to carb.

Good luck.

I am so glad I can laugh at myself. I checked the connection from the manafold to the carbs and discoverd I hadnt tightened the clamps that hold the carbs in. Oooops!

So of course I tighted them. Now the bike is back to not starting. Must be starving for air?

I will most likely take the carbs off again and reclean them and look into different pilots.

More to be revealed.

Well after some time and work. I have fixed the problem. All that was needed was to take of the manifolds and reseal them with Hondabond and clean the carbs again to make sure that are clean.

The bike runs great. Thanks for all the feed back. I wouldnt have known the path to take with out it.