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Hey everyone, first time poster here...
I have a 77 kz650b1, running with pod air filters and stock pipes. We're in the process of getting the carbs jetted correctly, and as near as we can determine, I need 12.5 pilot jets to get the mixture just right. She's running rich in the low range and fowling plugs after about 40 minutes of riding or so. My buddy is doing all the carb work for me and he says we need the 12.5 pilots to do the trick. The problem with this comes in the jets being on back order until sometime in May through any outlet in the Omaha, NE area. Does anyone out there know of an online resource I might be able to order these? Or any other outlet where they might be available? I'm itching to get the old girl on the road and don't really want to wait until May when we've had so much great riding weather here...any help is greatly appreciated. Thanks!!

I've never heard of anyone running 12.5 pilot jets in the 650's - that's REALLY small.

We barely ever sell any 15's and have never been asked for 12.5 before.

It sounds like you may have some other issues causing it to run rich - maybe poor spark / ignition timing, or poor compression / tight valve clearances, or a very high fuel level in the float bowl.

What do you have the air screw set at?

The air screws are set at 1 1/2 turns out. Any suggestions on where they should be are more than welcome.
We checked the points and condenser when we started tearing into the bike and they looked to be in good order. We're going to try replacing those and see if we get any better spark. Thanks for the tips, we'll look into all those areas and hopefully get the old kaw dialed in.

15's are stock. I didn't think going down 1 step was that bad.
the air fuel mixture screws were set to 3 turns out from closed, but seemed to run better at 1.5 from closed.

I wish i didn't have to post, but oh well.
I didnt really want everyone to know i am a complete moron

hey maxx,just saw your commercial again what a studd! hehe.goodluck,happy wrenching!

aren't i pretty.

In the 1977/78 era, Kawasaki tended to set the carbs very lean to appease the EPA. Once you start to modify the bikes with free-flowing air filters, you normally need to go larger, not smaller. Most of the KZ650's I'm aware of run either 15 or 17.5 pilot jets.

Hey Anarki, I have the same engine...with roughly the same set up and was recommended running 110 mains and 17.5 pilots...currently I have 102.5 mains and 15 pilots and the plugs are white. It must be another problem like the boys are saying;)

Thanks for all the help guys!!! I'll let you know what we figure out, hopefully soon!