CV34 rich issue

Hello All,

I'm new here, but have been looking at your forums for over a year now. The wealth of knowledge has made trouble shooting my 1982 KZ750 LTD much easier. I would like to hear some feedback on my current issue. My CV34 carbs have been updated with a 6Sigma jet kit. before I installed the jet kit I had a problem with the number 4 carb being way rich. While installing the jet get I thoroughly cleaned all carbs, ran small filament wire through all the holes, and cleaned again. I checked all of my floats height with a millimeter rule and installed new float needles. After installing the new jets the bike runs great except for the number 4 carb running way rich. The exhaust temperature is 150 degrees lower than the other three. Any ideas? Thanks in advance for your advise. Below are before and after pictures of my bike.

Hello, SubieWrench, and WELCOME to KZr!

...checked all of my floats height with a millimeter rule....

Even a precisely measured dry float height may fail to produce the correct fuel level.

A too high fuel level in an otherwise perfect carb results in a excessively rich fuel mixture.

Would perform the clear tube test in order to assure that the fuel level is within specs.

The clear tube test shows the actual level of fuel inside the carb float bowl, and is referred to in shop manuals as the "service fuel level."

The clear tube test is quick and easy to perform with carbs fully assembled and already installed on the engine.

While performing the test, the motorcycle should be on its center stand or being held upright balanced and level.

Good Fortune!

Thanks for the quick reply Patton. I will research on how to do this.

OK ran out and got some clear tubing and followed the instructions. this was the result. about 3.5 mm below the bowl seal line.

What's the float level spec in your manual? For my '79 KZ750 twin it's 4.6-6.5mm below bottom edge of carb body. Yours is likely different.

If fuel levels in the other carbs are about the same, can likely rule out fuel level as the issue.

Could remove or swap #4 pod for a test run to help rule out an obstructed pod.
And double-check to assure the #4 pod isn't obstructing entrance to the pilot circuit, as some pod designs are prone to do.

And renew or swap the spark plug in #4, and visibly observe for a fat blue spark on removed plug when cranking or kicking over.

If not already done, would perform a compression test and compare on #4 cylinder to the others.
And also check the valve clearances, especially on #4. If clearances are too tight, compression may be lost when the engine attains normal operating temperature.

Good Fortune!

Thanks for the updates guys. I have tested with the pods off, same result. Topper, mine calls for +/- 4mm. I will bring home my compression tester on Monday and check those. Then I will follow up with valve clearance as soon as time permits.