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Jet needle improves acceleration. 21 Jul 2011 10:56 #464115

  • calvin17d
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I am fantasizing about how the bike may run once I have 12.5 V at the coils vs. the 10V I have been running it at....? I am having visions of wheelies and smooth speedy operations up through the higher RPMs

Can anyone elaborate...............
1976 Kz900 A4

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Jet needle improves acceleration. 05 Aug 2011 15:37 #467042

  • jms3257
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I know this post is a week old but was curious just how it turned out, it just kinda stopped.

Jim
1980 KZ1000 LTD
Been away from riding for way too long, enjoying the journey back.

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Jet needle improves acceleration. 05 Aug 2011 19:18 #467084

  • calvin17d
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Well it was an electrical issue. I was able to bump the voltage at the coils up from 10 to 11v by cleaning the circuit board inside the ignition switch, which I would like to point out is an easy task and the idea of pulling the switch apart should not be intimidating.

Collectively across about 5 connections between my patch panel and the kill switch I lost the other volt. There was about .1-.2 volts of drop at all the bullet connectors. I'm sure the ignition wires need replaced. I live in Montana where the riding season is very short so I wired in a relay to supply the voltage needed to the coils. My winter project will involve replacing the circuit.

Now the bike runs much smoother through high rpm's. I did go back to the #4 clip position and put the stock pilot jets in. This is where I get the best performance. I now need to sync the carbs but haven't been able to pull the trigger on the vacuum gauges yet. Thanks to all for the help, and kzrider for providing a great database of useful encounters others have shared.
1976 Kz900 A4

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Jet needle improves acceleration. 06 Aug 2011 05:38 #467179

  • nads.com
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Gotta have full voltage to the coils or the motor will run uneven as a three legged dog.

No possible way to tune it that way,

UP
down
up
down lower
sputter
up
up higher
wait a minute
back down
quit
restart
high
low
repeat.

Dyna takes about 4amps and thats a voltage drop
Relays are a voltage drop. They take as much as one volt when parelelled with the dyna..

I have a question:

What is the voltage of stock coils? What about dyna's?

Not much without at least twelve going in.

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Jet needle improves acceleration. 06 Aug 2011 10:39 #467197

  • Patton
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nads.com wrote: Gotta have full voltage to the coils...
What is the voltage of stock coils? What about dyna's?
Not much without at least twelve going in.


Uncertain whether my understanding (as follows) might help answer the question ---

An ignition coil consumes voltage, and doesn't produce voltage except in the sense of high intensity output through the secondary loop.

Am uncertain about the method or need to measure the high intensity voltage.

I just visually observe for a fat blue spark at the plug tips.

But there's also a Kawasaki "electro-tester" to determine whether the coil is capable of producing at least a 7 mm spark.

Dyna-S requires switched battery voltage in order to function, whereby Dyna-S consumes voltage and doesn't produce voltage.

A good, fully charged, battery, properly serviced and connected, should measure 13+ volts between its terminal posts at idle rpm. And 14~15 volts at 4000 rpm.

Ideally, voltage received at the coil primary terminal should be identical to the measured battery voltage. But there's usually some minimal voltage drop due to loss through the circuit (wiring and connectors and switches) between the battery and coil.

Voltage at the Dyna-S should match the switched battery voltage of the harness wire where the direct single wire connection to the Dyna-S is spliced into the bike's electrical harness. This splice connection is often located near the dual connector where the ignition coils are supplied voltage via a red or red/yellow wire.

Good Fortune! :)
1973 Z1
KZ900 LTD
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Jet needle improves acceleration. 01 Oct 2011 20:09 #480831

  • wayno
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Hi cal,im new to the forum & this is my first reply.Ive just done the same things as you did & this is what i ended up with.My bike is a 7-76 kz 900.It was imported from the USA to Australia, & came with a 4 into 1 V/H pipes,& pod filters.it had main jets #122.5 in it and it went pretty hard i thought.Since then ive reset the valves to .003- .004 thou, fitted a 4 into 2 dunstall exhaust(with smaller dia pipes7 primaryies that are 32 inches long before the collector) ,pod filters (using the original air box rubbers, the original pod rubbers were distorted & had no radiused entry into the tube.The original kawasaki items are bell mouthed which picks up the flow rate), dyna ignition, & a rejetted carb.With the bike running ive got 15v at the battery & 13.9v at the coils.With a wide band oxgen sensor, ive rejetted to 130 all carbs & a #2 on the needle.This combination had AFRs of 11.9 midrange (too fat) & 13.1 ( a tad lean)wot peak revs. ive since fitted the neele clip to #3 & fitted #132.5 to the inner cylinders & lightly reamed the #130 to about 132.the AFR are now 13.5 mid range,(this is where you do most of your riding)& the wot reading was 12.5.PERFECT. The staggered jetting is to help the centre cylinders run a little cooler on the exhaust gas temps.Since these mods the bike is a dream to ride & it pulls hard.Use these jetting figures as i guide only.I live at sea level, which will alter jetting if you live well above sea level.My best tip to all readers is to buy a wide band AFR meter and adjust jetting accordingly.Forget plug chops & hi speed runs,they are unreliable & dangerous.ihope that this has been some help to you.One last thing, check that the manifold that bolts to the head.It can distort & reduce the port opening 3-4 mm. some quick work with the die grinder fixed my issues.wayno
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Jet needle improves acceleration. 15 May 2012 01:08 #522454

  • spark23ca
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as a rule with carbs.. i used to race snowmobiles ..air mixture is for idle...pilot is for idle to quarter or even 1/8 ..and then the main jets and needles are for where the pilot shuts stops to wide open..sometimes the floats will let the carbs go lean on half to full throttle ..i've had to raise the float to a little more then level to run pipes on sleds b4
1982 kz 1000 ltd ..someone started to make a bobber out of it and realized it didnt' run and they didn't know how to run their wrenches

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Jet needle improves acceleration. 11 Jun 2012 19:04 #528260

  • Medina
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Stupid question on needle:
shimming vs. purchasing that c-clip version

I had a honda, over at that forum it was common to simply take a MACHINED washer (NOT those stamped ones) buy a dozen, mic out four that were identical and literally use them as shims to lift the needle upward.
The sizes slip my mind, but I got a dozen from sears- machined bronze for a couple of bucks. Huge, immediate improvement, to-day on that 550 I had.
Does that not work on the KZ engines/carbs?
1981 KZ1100 Vetter "Luminous Navy Blue" DAMN YOU COLOR CODES!
Medina, Oh
My Bike Thread
www.kzrider.com/forum/10-new-members/469298-from-ohio

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Jet needle improves acceleration. 11 Jun 2012 20:33 #528287

  • DoubleDub
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Some carbs have the clip positions in the needle, others don't. For those that don't, I believe you can use shims for some of them.

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Jet needle improves acceleration. 02 Jul 2012 14:30 #533370

  • spudbudy
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Well I'm not exactly sure but on my bike with vm26 carbs the needle clip position had a big impact I used a afr wideband o2 sensor fot he testing. The test was done @ 5k or approx 65 mph.
78 KZ 650B2. Vetter faring, Dyna S, Dyna Green coils, WG coil mod,AGM Battery, VM26SS carbs, Pilot jet 15, mains 110, jet clip #2 shimmed position, Modified stock air box, stock air filter, Kerker 4 into 1 with stock baffle. currently 48,785 miles. :-) and climbing daily.:-)
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Jet needle improves acceleration. 15 Nov 2012 06:03 #558438

  • nads.com
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You know your raising the needle gives more gas to the midrange,
but won't help the lean condition at wot. This post is too long
to read it all, but if your running a 1015 or 1075 with 26's,
it's way too lean and is running out of gas at around 6 grand.
my 1015 ran weak at the the top with 120 jets. You need a 130
something in there if it's 10 to 1. And the front end will come
up easy. Those are goood wheelie carbs because of the controlled
acceleration but at the end of the day, Way to small to reach
potential reality.

I've got 34's on mine and they open slow and are out of control,
(like all cv carbs) but they open the motor up let here run.

Those 26's are giving the head a sucker face big time.

Don't choke your chicken, even though the carbs are too small,
give the motor more gas and it wil have a new animal alltogether.

Up or down on the needle and you lose it all. The pilot should be
3/4 to 1- 1/4 and thats it. Any more or less and your getting offf base.

going from 120 to 130 is like riding a pony then a race horse.

Now you have me thinking about those kheins again dammit!

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Jet needle improves acceleration. 15 Nov 2012 09:47 #558449

  • Patton
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"Jet needle" clip positions ---

Lowering the clip raises the needle, increasing fuel mixture through the needle jet, and thereby enrichens the mixture throughout mid-range of the carb.

Raising the clip lowers the needle, reducing fuel mixture through the needle jet, and thereby leans the mixture throughout mid-range of the carb.









Good Fortune! :)
1973 Z1
KZ900 LTD
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