Sorry another jetting issue. 79 kz1000B

I know everyone asks about it, but nobody ever finishes with thank you that worked. I have a 79 Ltd 1000, chain drive, "if it matters" I read the forum and realized i made a mistake, i bought Emgo filters, i have a mac 4 to 1. i upped my main jets from 117 to 122.5, and my pilots from 15 to 17.5. it ran great before, after pods and pipe, it has more bottom end, cuts out and backfires about 4, pulls hard again after 5500. plugs come out white up top so i figure it's lean. i believe my carbs are 28s.

Hello, 79Ltd1000! Welcome to KZr! We're glad you're here and anxious to help.

If reading correctly, you have doubts about the Emgo pods, are having engine performance issues between 4000-5500 rpm, and get lean plug reading after high speed plug chop.

Are these the stock carbs (believed Mikuni 28mm manual slide with side located pilot air screw adjusters)? Looks like you went up two sizes on the main jets and one size on the pilots.

How was the bike set up when it ran great before? Airbox? Were the pods and 4>1 installed at the same time the jets were changed? Did the Mac replace a more restrictive (stock?) exhaust? Are the Macs open or using baffles?

the mac replaced the stock exhaust. before it was stock pipes and stock air box. it ran great. the filter and pipe was changed, the mac pipe is baffled. they were all done at the same time. lean with a bad dead spot with backfiring. i don't believe my stock carbs have the adjustable needle and i don't want to take them out of sync adjusting the air screws.

79Ltd1000 wrote:

the mac replaced the stock exhaust. before it was stock pipes and stock air box. it ran great. the filter and pipe was changed, the mac pipe is baffled. they were all done at the same time. lean with a bad dead spot with backfiring. i don't believe my stock carbs have the adjustable needle and i don't want to take them out of sync adjusting the air screws.

While the Kawasaki.com diagram may be incorrect, it seems to show the 79KZ1000LTD carb jet needle with different clip notches, and pilot fuel mixture screw on the bottom (as opposed to a side-located air screw).

You could try enrichening the pilot circuit mixture by turning the bottom located adjustment screw counter-clockwise (screw it out a little, say 1/4 - 1/2 turn) as an experiment for any effect on the 4000-5500 rpm problem. (If a side located air screw, turn it in clockwise to enrich). Pilot screw adjustment (bottom or side) does not affect existing synch settings.

WOT mixture is primarily dependent on the main jet size, regardless of the jet needle clip position.

I agree it would be best to re-sync after relocating clip position on the jet needle.

Are all other non-carb components up to snuff (compression, ignition, fuel delivery, etc.)?

I have read that pods are more difficult than an airbox filter to obtain optimum fuel mixtures throughout the throttle range.

I expect others will have better and more detailed advice as to best adjustments for your particular setup.

Good Luck!

Here's the diagram.

I'm not nearly as good at carb problems as some guys in this forum are but I do know that if you use pod filters on a four cylinder you can run into problems with the inside 2 cylinders starving for air a little while the outside 2 are being force fed. This could cause a lean condition on cylinders 1 and 4 and rich on 2 and 3. Did you check all of the plugs and not just one??

79Ltd1000 wrote:

the mac replaced the stock exhaust. before it was stock pipes and stock air box. it ran great. the filter and pipe was changed, the mac pipe is baffled. they were all done at the same time. lean with a bad dead spot with backfiring. i don't believe my stock carbs have the adjustable needle and i don't want to take them out of sync adjusting the air screws.

I'd try the stock airbox with the MAC pipe. When you change two things at once, you can't tell how much harm is done by each. This kind of story is what I read a lot when people use air pods. My memory is that the 900 - 1000 are particularly nasty to try to get to run with pods.

79Ltd1000 wrote:

I know everyone asks about it, but nobody ever finishes with thank you that worked. I have a 79 Ltd 1000, chain drive, "if it matters" I read the forum and realized i made a mistake, i bought Emgo filters, i have a mac 4 to 1. i upped my main jets from 117 to 122.5, and my pilots from 15 to 17.5. it ran great before, after pods and pipe, it has more bottom end, cuts out and backfires about 4, pulls hard again after 5500. plugs come out white up top so i figure it's lean. i believe my carbs are 28s.

If it gets strong after 5500, then your main jets are probably large enough and don't need adjusting. You can try going up to the next larger main jet and see if you get more power at the high RPM, wide open throttle range.

"cuts out and backfires about 4"

This sounds like the best "knob" to tweak would be needle position. Rich it to the max and see if it gets better.

Do you have an accelerator pump assembly? Does the accelerator pump actually work?

Thank you everyone for giving me info. WiredGeorge you nailed it. I read about it in my service book and re adjusted it accordingly. no more deat spot. no back fire or cutting out. The weather's gonna be good sunday then i'll run it for 10 minutes and check the plugs, rejetting accordingly if need be. thanks again, what i thought was another couple jets sets was only a 20 sec fix. Didn't even have to pull the carbs. thanks again everybody.

still not perfect. small dead spot. between 1/8th and 1/4 throttle. plugs look rich at electrode but lean on the tip. if i ride it through a parking lot at low rpm when i open it on the road it backfires. if i put it in 3rd or fourth and leave it open for 10 to 15 seconds it clears out. but i know it's loading at low rpm. i think it may be rich at around 1/4 throttle. that might be the dead spot. the acc. pump is set to rich only 2 threads on the back side.

The problem with trying to rejet accelerator pump carbs is that the pump just pops a squirt of gas into the combustion chamber to compensate for lean jetting. When you rejet, you still get the squirt which isn't really needed. The transition from 1/8 to 1/4 throttle is probably still a bit lean. Hard to tune with the pump in place.

is there a delete kit? just change the bowl. i thought it was too rich between main and pilot operation. it seems to load up.