KZ 550 idle problems after warm

Bike is running great, but when I stop after being on the highway my bike always wants to die. Driving around town I usually don't have a problem just after extended rides on the highway.

Any idea?

Flyndrive wrote: Bike is running great, but when I stop after being on the highway my bike always wants to die. Driving around town I usually don't have a problem just after extended rides on the highway. Any idea?

Valve clearances been checked lately?

Good Fortune!

That's what I was thinking just need to find he time to do it.

The harder you ride on the highway, the more it will want to die at the first stop.
After a few minutes of riding slow, it will tend to run normal.

That is the first symptom of your valve clearance being too small. This means one or more valves are not sealing while riding on the highway.

You should stay off the highway until you adjust the valve clearance.

Read the valve train warning in my signature, if you havent already. It also has a better picture of how the valve timing should be set.

So I got to check my valve clearances. They were all within limits, one on the small limit.

Here they are:
1- intake .006 exhaust .009
2- intake .006 exhaust .008
3- intake .008 exhaust .009
4- intake .007 exhaust .006

Limits are; intake .004 - .008 exhaust .006 - .010

The #4 exhaust is the only one at the limit, could that be my problem with idling after being on the highway? Or could there be something else? Should I do all the work for that one clearance?

Reported symptoms: Bike is running great, but when I stop after being on the highway my bike always wants to die. Driving around town I usually don't have a problem just after extended rides on the highway.

Flyndrive wrote: So I got to check my valve clearances. They were all within limits, one on the small limit.

Here they are:
1- intake .006 exhaust .009
2- intake .006 exhaust .008
3- intake .008 exhaust .009
4- intake .007 exhaust .006

Limits are; intake .004 - .008 exhaust .006 - .010

The #4 exhaust is the only one at the limit, could that be my problem with idling after being on the highway? Or could there be something else? Should I do all the work for that one clearance?

Valve clearances look okay. Symptoms likely resulting from something besides improper valve clearance.

Good Fortune!

Engine might be "loading up" from too rich mixture in mid-range operation (maybe needle clip on throttle slide is one notch too low).

Or maybe there's weak spark (for whatever reason).

Or maybe the timing advancer is hanging after extended running in forward position (may require lube, or both cleaning and lube).

Would also verify correct adjustments on the pilot screws, to help assure best fuel mixture at idle.

Good Fortune!

After getting off the highway, does the bike start to run normal after a minute or so?

If you drive it on side roads for an hour or so, does it ever have the symptom of wanting to stall out?

How hard/long did you ride it on the highway, and how was the ambient temperature?

I just have never heard of something else that causes the symptom of the bike running great all the time except for stalling right at the end of a highway run (of at least 30 minutes or so).

Sometimes the heel of the cam lob is not perfectly round. Maybe there is a spot on one of the cam lobes that has a little less clearance than the others. I always check multiple locations on the heel when I do the clearance check, not just the one position the manual says to check. I usually check +/- 10 or 20 degrees from the center of the heel.

But usually, when I get the symptom I'll have at least one valve at .001 less than spec, so maybe there is another cause.

You could put it back together, and see if the symptom gets worse over a month or so. Hotter weather will always make the symptom worse.

Could it be just an air mixture screw problem. I'm running them at 1 1/2 turns out.
When it sounds like its going to stall if I blipp the throttle the RPMs come up and then it take 5 seconds or so to come back down to idle. Is that normal?

Flyndrive wrote: Could it be just an air mixture screw problem. I'm running them at 1 1/2 turns out.
When it sounds like its going to stall if I blipp the throttle the RPMs come up and then it take 5 seconds or so to come back down to idle. Is that normal?

Perhaps the engine is over-heating -- for whatever reason -- during an extended higher speed run.
Such over-heating could result from a variety of causes, ignition related or fuel mixture related.

The delayed return to idle rpm is likely due to an air leak, which could also contribute to the over-heating during extended higher speed runs.

Even without an air leak, if the pilot screw settings haven't been fine tuned for best performance at idle rpm, a slightly over-heated engine might be more prone to stalling at idle rpm.

As known, an air leak will basically disallow fine tuning of the idle circuit.

Are spark plugs the correct heat range?

Good Fortune!

What ignition does this bike have, points or electronic?

Would use a strobe-type timing light to check the ignition timing AND also check operation of the timing advancer.

Good Fortune!

Flyndrive wrote: Could it be just an air mixture screw problem. I'm running them at 1 1/2 turns out.
When it sounds like its going to stall if I blipp the throttle the RPMs come up and then it take 5 seconds or so to come back down to idle. Is that normal?

That's strange.
With valve-clearance too tight, it will just run rough at idle, and a blip will come right down to rough idle. Then it will all smooth out as the engine cools.

Your problem sounds almost a heat-related vacuum leak. But I can't really imagine how.