Oil fouled spark plug...

If not already done, would perform the clear tube test on carb #1 to determine whether the fuel level is within specs.

A too high fuel level may result in excessively rich mixture.

Good Fortune!

Gotta agree these kawis sit for long periods of time on their kickstand and all the fuel and angle goes to the number 1 cylinder..

Probably wrong but for me I always in my mind blamed my petcock and angle for the bad #1 cylinder.. I had years ago ran a clear glass filter off the petcock just so I could see fuel level sitting and running..

Sometimes sitting u would see 100% filter full.. Sometimes on start up you would see barely any fuel in filter..

Visually it's a great addition to help problem solve..


Also if the bike is somewhat new to you look at where the set screws are on #1 compared to the rest.. I've seen a lot of backyard adjustments on these only after using a mirror and light to compare all 4 carbs set screws ..

Hey thanks everyone for the advice! I really appreciate it. I will try a leak down test this weekend hopefully and see what I come up with. Now as for a clear tube test...I've heard of that but I have never done that before. Can someone explain it a little to me or I can just read a thread about it. Thank you again

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The carb is designed to best perform with a certain specified level of fuel inside the float bowl.
A too high fuel level results in an excessively rich mixture throughout the throttle range.
A too low fuel level results in an excessively lean mixture throughout the throttle range.

The objective of the CLEAR TUBE TEST is to determine height of fuel level inside the float bowl.
When the test is performed correctly, the level of gasoline visible inside the tube will match the level inside the float bowl.

Carb must remain in a stable level position during the test, such as motorcycle on centerstand or otherwise held steady in a balanced level position. Or carbs may be held level on the workbench.

First -- prevent gasoline supply to the carb, and then drain the float bowl.
Which leaves an empty carb with a dry float bowl.
Next, attach the clear tube and hold it steady alongside the carb.
Then, allow gasoline to enter the carb.
The incoming gasoline passes through the float valve and into the float bowl.
As the level of gasoline rises inside the float bowl, the level of gasoline also rises inside the clear tube.

If the float valve is correctly functioning, the float will rise high enough to close the float valve, at which time gasoline stops entering the float bowl, and remains at a fixed level inside the float bowl and at the matching level visible inside the clear tube (either too high or too low or within specs).

Learning the actual fuel level inside the float bowl completes the clear tube test.
If the fuel level is too high or too low, "adjusting" the fuel level is a separate procedure, which involves changing how soon the rising float stops gasoline flow through the float valve.

Good Fortune!