One wet plug, one dry plug

Time to educate a noob.

I've noticed that on the occasions when I have trouble kick starting my '79 KZ twin that one plug will get wet and the other plug will be bone dry.

Left plug is always wet, right plug is always dry.

Is that normal or a sign that something's wrong?

Try swapping ignition wires.

Swap plugs. See if the "Wet" follows the plug (plug problem) or stays with the cylinder.
If it stays with the left cylinder, swap the plug wires. If it follows the plug wire, check the plug cap/coil to cap wire.
If it continues to stay with the left cylinder, check to see if you are leaking fuel into the cylinder assuming you store bike on the side stand.

Good Luck,
Jim

Did the engine start? It should start and run on one cyl. Not very good but still run. it could be carb. flooding on the wet side. Or ignition problem on the wet side as mentioned in previous post.

When it starts it runs fine. It definitely runs on both cylinders.

It's just when it doesn't start I pull the plugs to check and see if they're fouled and the left one is always wet and the right one is always dry. I'm starting it on the center stand.

Does it have a vacuum petcock connected to the "wet" cylinder? If it does, it is likely getting gasoline through the vacuum hose.

The petcock diaphragm was the culprit on my 79/650 as it connects the the #2 carb. The #2 plug was always wet. I also have a fuel accelerator pump on the bottom of my #2 24SS carb. it too has a diaphragm that needs to be good in order to prevent fuel leaking into the carb.

Just saying this out loud knowing you have a twin. Also check the OHM flow on the spark plug wire to be spec and make sure the wire caps are in good condition.

And when you notice gas on the plug, Always check your oil for gas contamination - could lead to other problems, Although I have never heard of a bike exploding due to oil contamination.

best of luck

Mine is a 4 as well but I'd guess the twins has the same system. At least it is identical on my girlfriends twin Suzuki GS450S (which has the same carbs as my 700/4) and I just fixed the exact same problem on it. Broken metal pieces from the diaphragm kept it open and caused gas in the vacuum line.

Yes, do smell the oil through the filler cap. Contaminated oil doesn't lubricate enough and could cause all kind of trouble.

The 79 KZ750 twin has no vacuum petcock it's just a mechanical valve notorious for leaking.

If you have a side flooding, you have to take the needle and seat out of the carb and polish smooth so they will seal. Then use the clear tube to set the fuel levels 5mm down from the lower edge of the bottom of the top half of the carb,

This flooding ritual is so common I used to drop the bowls on mine every six months and clean and polish the needles/seats as routine maintenance on mine to prevent it.

NOTE: make sure you are turning the fuel petcock to OFF after riding or it will flood cylinders.

I'm not convinced it's flooding while sitting. I don't really know because I don't normally check unless there's a problem starting. It's been sitting (at work) for a few days. I'll check the plug before I try to start it tomorrow morning.