Possibly Running Lean?

Here are a couple of pictures of my cylinder head. I'm not sure what the indications of the valves are. Any advise as to what the problems and solutions might be, if any? Thx in advance!

I guess this is good? My concern was the 2&3 cylinders.

Looks lean on those 2, how old are the carb boots. Is that a wide open run look or normal street riding? Im no expert though but Ive been running them since the first Z1 came out, still own 2 of them plus a stock 1000 and an 1105 KZ

It is street running only. The carb boots are original as far as I know and do not leak as I have tested with carb cleaner and no rpm increase.

those plugs are WHITE its definetly running lean thats the jeting?

the exhaust valves are white because of the exhaust temps from running lean. holes two and three are whiter because those two holes dont get as much air flow past them so they run hotter. how bad did your headr glow at night?

I don't ride a lot at night so I'm not sure. I have the recommended jets (117.5 I think) from someone on here. Should I raise the clip on the needle or rejet? I have the bike apart now to replace the cam chain, so it would be a good time to do it.

Hope engine isn't "pinging" under load.

Before going into carbs, would first perform clear plastic tube test to assure service fuel level in float bowls is within specs. Too low levels may result in excessively lean fuel mixture even in otherwise perfect carbs.

Would also assure ignition timing is correct and that advancer is working. Best to use strobe-type timing light. Incorrect ignition timing or faulty advancer can cause overheating.

Good Luck!

I have the Mukuni carbs and I don't believe I can do the clear plastic tube test but I have measured them the last time I had the off and they were good (floats). As far as the timing, I have a Dyna S that I installed correctly as far as I know and will have to get the bike running to do a light check.

letthegoodtimesroll wrote:

I have the Mukuni carbs and I don't believe I can do the clear plastic tube test but I have measured them the last time I had the off and they were good (floats). As far as the timing, I have a Dyna S that I installed correctly as far as I know and will have to get the bike running to do a light check.

The clear plastic tube test is quick and easy, and is superior to the upside-down while disassembled-on-the-bench dry measurement method which may get in the ball park but often misses the mark. (But admittedly, some folks do in fact report achieving consistent and accurate results from using the upside-down dry measurement method. This being after verifying the level by performing the clear plastic tube test, which is the only way to positively know, without any doubt).

And it may take longer to read this post than to actually do the test. :lol:

Here's how to perform the "clear plastic tube test" which checks the real-world float bowl service fuel level as it exists under actual operating conditions.

The test may be done while the carbs are on the bike and with no disassembly required (other than removing the float bowl drain screw).
And may also be done with carbs on the bench (holding them level of course).

Do each carb separately, one at the time.

Carbs must remain still and level during the test. May place bike on centerstand, or have an assistant hold the bike level.

Turn petcock off.
Fuel line remains attached to carbs.

On Mikuni manual throttle slide carb, remove side-located drain-screw from float bowl,which drains and empties the float bowl. The overflow nipple from bottom of floatbowl is not involved in the test on Mikuni manual throttle slide carb.

Must begin the test with an empty float bowl.
May use a shop rag to catch and soak up outcoming fuel.

Use short length of clear plastic tube.
Size of clear tube should match drain-screw hole.
Twist-thread clear plastic tube into drain-screw hole.
Some folks prefer using a small plastic barb-style connector fitted into the drain-screw hole with the clear tube attached to the connector, but it's really not necessary, because a little leakage doesn't invalidate the measurement.

Now here at this point is where the bike must be on its centerstand or being held level, because the carbs must be level.

Allow tube to loop naturally without kinking, and hold clear tube against top edge of float bowl.
Keep it steady - don't let it move.

Turn petcock on.
Watch level fill and rise up in clear tube as fuel fills float bowl.
Fuel level visible in tube matches fuel level inside float bowl.
Slight fuel leakage from the drain-screw hole is immaterial and won't invalidate the test.
Repeat test to double-check result.

There is a special fuel level tool available for fitment into side-located drain-screw holes. It is a relatively expensive thumb-screw affair with clear tube attached that threads into the drain-screw hole.

Refer to manual for specs as to ideal height of service fuel level.
A typical "correct" fuel level is slightly below the float bowl gasket,
say 1/8 inch or 2-4 mm.

Float height is a critical factor for proper carb function, and once set, should last a very long time without needing any re-adjustment.

Actually, the "testing" is much easier and quicker than the "adjustment" of a float tang which requires removal of the float, bending the tang, replacing the float, and again testing the level.

During the float tang adjustment process, it's okay and faster to use only one float bowl screw when checking the level between adjustments.
(This time and effort saving tip is courtesy of wg).

As known, small adjustments to the tang make large
differences in the fuel level, so go with tiny increments.

Hopefully, the test will show all the fuel levels being just fine, and without needing any adjustment, which eliminates from the list of suspects a too high (rich) or too low (lean) fuel level as the cause of an apparent fuel mixture issue.

Additional informtion about this test and float tang adjustments may be accessed by typing clear plastic tube test in the above Search Forum box, and clicking on Go, which should result in a list of several threads where the topic is discussed.

Good Luck!