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Rejetting carbs after major work

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08 Sep 2021 17:42 #855018 by rokit_armor
Replied by rokit_armor on topic Rejetting carbs after major work
Well, I think I found the culprit. Rejetted the carbs with 32.5 pilots and 107.5 mains and it was still WAY rich... I had a strange feeling about something, so I took a look at the jet needles. Apparently I had Keihin 272304 needles in it... 2.5mm diameter compared with the 3mm diameter of the stock (4CG15 according to FSM) needles it was just flooding the carbs all the time.
I have a suspicion the shop I had taken it to previously, dropped them in to compensate for the lean condition of the pods/exhaust.
I had a set of 5GX28 needles sitting around (I guess these were also used in the kz1100's?) from the rebuild kit I got years ago. Popped em in and it idles now- just hella lean from the jetting.
Bloody hell.

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08 Sep 2021 18:35 #855023 by rokit_armor
Replied by rokit_armor on topic Rejetting carbs after major work
I remembered now, as I also had a set of Keinin main jets. I rebuilt the carbs on a CB500 and the stuff must have gotten mixed around.

A little backstory with a PSA tied to it. I was divorcing my first wife when I picked up this KZ and joined the community here in 2013. The abuse from my marriage and the new life I had left a hole in my that I filled with alcohol. Slowly but surely over the next three years I became severely alcohol dependent. Drinking myself to sleep every night kind of alcoholism. There are a lot of things I don't remember well from this time - like even owning the CB500. Im pretty sure 95% of the posts I made here were under the influence. To be honest I should probably not be around right now (seriously kids, don't drink and ride).
I sobered up January 11th, 2017 and boy was that ever a good decision. I now have full custody of my kids; turns out when my ex could not longer abuse me she took it out on the kids. I have a happy new blended family and a much better career.

Phew, ok now back to the fun of jetting these carbs!

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11 Sep 2021 16:24 - 11 Sep 2021 16:27 #855136 by rokit_armor
Replied by rokit_armor on topic Rejetting carbs after major work
It is tuned to the point of idle now, I'm following  Factory Pros CV tuning guide ,  but I keep hitting a roadblock of even getting it to rev to WOT for tuning the main jet. It bogs no matter what I do, go leaner or richer. The carbs are all spitting fuel back into the pods, is my cam timing off allowing this to happen? The cams I have are slotted for fine tuning timing, and since I don't have a dial wheel I put them somewhat centered.

What else could cause this condition?
Embedded video doesn't seem to work, here's a link.

Last edit: 11 Sep 2021 16:27 by rokit_armor.

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13 Sep 2021 10:37 #855217 by Matt bx
Replied by Matt bx on topic Rejetting carbs after major work
Maybe a bad float needle? 

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  • DoctoRot
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  • Oh, the usual... I bowl, I drive around...
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13 Sep 2021 14:43 - 13 Sep 2021 14:46 #855228 by DoctoRot
Replied by DoctoRot on topic Rejetting carbs after major work
A couple degrees of cam timing can greatly effect performance, and very well could be the source of your problems.  I would not spend any time tuning the carbs until the cams are properly timed.
Last edit: 13 Sep 2021 14:46 by DoctoRot.

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14 Sep 2021 04:17 #855242 by Rick H.
Replied by Rick H. on topic Rejetting carbs after major work
I agree with DoctoRot on this.  You are spinning your wheels until the cams are timed in properly.  A bit off one way or another can have a serious impact on how it runs.  Cam timing needs to be correct.

Rick H.

Rick H.

1977 Kawasaki KZ-1000A1

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03 Oct 2021 10:24 #856134 by rokit_armor
Replied by rokit_armor on topic Rejetting carbs after major work
I will see about degreeing the cams. I'll need to get a few tools for that. I'll follow Web Cam's degreeing guide
My issue with the 'way too rich' was my muffler packing I did. It was causing too much backpressure.
I've sync'd the carbs, and jetted it to running mostly correct. I'm just having an issue with the pilot circuit; top end and mid-band is great. I no longer have any backfiring through the powerband either.
Here's what's up:
* Idle is set low, about 500-750, any higher and it runs away immediately with any throttle (no load) 
* Blipping the throttle is fine, unless it hits 1200 then it hangs and slowly returns
* Under load, engine bogs between 750 and 1200, is 'ok' until 2000 then pulls hard
I currently have 47.5 pilots with the pilot circuit screw 3.5 turns out. (Main jet is 137.5, needle is shimmed up with one washer)
Am I correct in thinking going up a size on the pilot jet will reduce the hanging RPMs between 1200 and 2000, and leaning out the idle circuit screw will fix the bogging at 750-1200?

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