Stumped! Carbs valves electrical or what?

Hello Again Everyone,

Here's my current situation #4 spark plug is carbon fouling and other 3 range from great to a bit rich looking. I've attached two pictures below. One with a set of B8ES plugs and the other with B7ES
I've been chasing this problem around for a while now but can't seem to nail it and would appreciate any help or pointers I can get. I'll give you all the info now

The Bike is a '76 Kz650 that's been bored up to a 738cc . I have not checked compression but the bike runs powerfully when plugs are fresh. I Recently shimmed the valves and degree'd the cam (it has a .410 lift cam in it)
I'm running VM29 smoothbore Carbs that are currently set up with a 120 main jet and a 20 pilot jet. I had 25 pilots in before but had the same issues. The carbs have been dipped and blown out with an air compressor. I took them off again today and used carb cleaner and the compressor focusing on air jet and other air paths hoping there was just a clog. Everything seems clear but the problem persists. I've tried different setting on the air jet ranging from a 1/4 turn out to 3 turns out on carb with the fouling plug but it doesn't seem to help. The carbs have two two into one pod filters.
I've Pretty much switched out the entire electrical system and have tried swapping plug wires around with no luck. It has Dyna S cdi with dyna 3 ohm coils an electrosport stator and electrosport reg/rect. I've dialed in the cdi with a timing light.

I'm a novice to performance tuning so any help would be greatly appreciated

Zac

738cc would mean you have a 750 top end. Im not familiar with the 29 smoothies, but Is there a vacuum port our something on the number 2 carb that could cause an air leak? You may have to run a small wire through the passages in the carb, sometimes solvent and air are not enough to cut it. Since the other plugs look ok, I'd concentrate on that number 2 carb. Have you done a carb sync? And did you check your vale clearances while you were degreeing your cams?

There's no such thing as a 1976 KZ650. Maybe you mean it is a 1977 KZ650 that was built in 1976? Ed

Yes Ed, Built in '76 but I guess it's a 1977 650B It was first registered as a '76 so that's what threw me off

Did you clear tube test the bowls?
Steve

I have not . I bench set the float heights to 25mm but have noticed it will drip gas out of the fuel filter when parked . the bike is side stand only and is parked nose up on a pretty good hill so I'm not sure iif this is to be expected or a symptom of high float levels . I have to get the attachment that screws onto the float bowl so I can test them.

I would suggest you do that.
Steve

If u have a good spark at each plug...then it's your carbs.
Need a good cleaning...meaning and most likely take them apart .
I

Could be a combination of things. Oil fouling due to bad valve guide seals causing poor spark, followed by too rich a mixture. If it's burning oil, it will have to be run leaner.
Steve

Dirtyhands wrote: I have not . I bench set the float heights to 25mm but have noticed it will drip gas out of the fuel filter when parked . the bike is side stand only and is parked nose up on a pretty good hill so I'm not sure iif this is to be expected or a symptom of high float levels . I have to get the attachment that screws onto the float bowl so I can test them.

Can use a conical rubber grommet or section of rubber hose fitted into the drain hole which serves as a connection for the clear tube.





Have never used or needed the "special tool."

Minor gasoline seepage, if it can't be avoided, doesn't affect the clear tube test.

Good Fortune!

That's a cool trick Patton, Thank you! I'm gonna give it a shot come my next day off. Would an excessively high float level contribute to fowling plugs?

Yes and more.
Steve