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Z1000A1 carb setup

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Mr Bump
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Z1000A1 carb setup

#1 PostAuthor: Mr Bump » Wed Dec 19, 2018 8:50 pm

Evening all,

So, I've got a z1000A1:
100% stock engine, freshly rebuilt with good compression
Vance and hines exhaust with baffles in
std carbs, main jets increased to 117.5
Standard airbox with (clean) K&N filter in it, snorkle missing

I know:
Valve clearances correct, timing correct
New plugs
carbs stripped, ultrasonically cleaned, balanced, set up using genuine manual
Float levels spot on
Clean petrol in it
New Dyna ignition that appears to work spot on.
Keyster carb kits in all four carbs


Problem is that its got an annoying flat spot just off idle. Starts and runs really well other than that. I can ride round it but it bugs me. What it does is sort of bog on all four and puff out a bit of black smoke as it picks up, seems like it briefly runs rich as the throttle is opened.

I've messed about with needle heights, pilot screw settings, all that stuff and ended up back at standard settings. Balancing and re-doing float levels helped a fair bit but didn't get rid of it.

Plugs are kind of sooty round the edges but the white insulator looks too white, not light brown.

I first ran the bike a couple of years ago with the original needles and jets in it, and I dont remember it having a flat spot, but I've got a head like a sieve these days so I'm not certain. The keyster kits got fitted because I found one carb had a bent needle in it which had ovalled the needle jet.

So, I'm thinking:
(a) is it the carb kits? the OEM needles were very smooth; the Keyster ones are a rougher finish you can feel with yr fingernail. I've tried chucking the old needles back in but didn't get a result. I cant put the old needle jets back in as I distorted them when I drove them out.

(b) does the half-standard airbox mean I need some air corrector jets as I've read about on here? I believe Zed1015 was selllng some a little while ago.

(c) both, or something I've missed?

I've run out of ideas and dont want to start randomly chuck parts at it without a plan. And I'm fed up with taking the carbs off.

Can anyone offer any advice?

Thanks, Olly
'In your twenties you think you are immortal, in your thirties you hope you are immortal, in your forties you just hope it doesn't hurt too much'

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Re: Z1000A1 carb setup

#2 PostAuthor: DavidZ1R » Wed Dec 19, 2018 9:33 pm

I had exactly the same problem with my z1000a1, flat spot between 2 and 3000 revs, found first that I could not get a blue flame on the old gunson on two cylinders, found that the threads on the pilot screws were not clean due to residue from the vapour cleaning, improved tick over but still had the flat spot, after taking the carbs on and off more times than a who res knickers, trying everything guys suggested, the only thing I had not done was to change the tiny soft spring behind the main needle, I changed them all with the new much firmer springs in the kits, raised the needles one notch, result perfect, not sure if it was the springs or raising the needles, but not touching it , runs great.
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Mr Bump
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Re: Z1000A1 carb setup

#3 PostAuthor: Mr Bump » Thu Dec 20, 2018 3:13 pm

Well I’ll be darned, there’s supposed to be a spring and washer below the needle clip and a spacer above according to parts fiches - they’re all missing from mine and I never noticed. I assumed the springs were for the pilot needle, not the main needles. Best try that next then.

Has anyone got any spare spacers and washers hanging about? Cms nl list them so I’ll get new if not.

Olly
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Lemmy

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Re: Z1000A1 carb setup

#4 PostAuthor: DavidZ1R » Thu Dec 20, 2018 4:26 pm

Make sure the carbs are the right ones as the parts list, some earlier carbs never had them.there will be a space under the retainer clip for the spring.
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Re: Z1000A1 carb setup

#5 PostAuthor: DavidZ1R » Thu Dec 20, 2018 4:28 pm

Also the air screw spring is longer and thinner than the main needle spring.
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Re: Z1000A1 carb setup

#6 PostAuthor: zed1015 » Thu Dec 20, 2018 6:48 pm

If you need some air corrector jets I still have some sets for sale here via PM or from my ebay listing BUT I doubt you need any as they are to correct the LEAN condition off idle caused by the use of open carbs or high flow filters.
Just removing the snorkel from the airbox but still using a filter shouldn't lean out the mix to such an extent as to need them.

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Re: Z1000A1 carb setup

#7 PostAuthor: Mr Bump » Fri Dec 21, 2018 8:18 pm

Ideal, thanks for your guidance chaps. I’ll get to it as soon as I get time.... and I’ll post the results.

Cheers.
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Lemmy

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Re: Z1000A1 carb setup

#8 PostAuthor: Mr Bump » Tue Jan 08, 2019 1:40 pm

Afternoon,

So I’ve got round to taking a throttle slide and needle out. I’ve got a set up I can’t find on a fiche online and isn’t shown in my genuine z1000a2 manual (note that I have an A1).

In the A2 manual I’ve got a nice illustration of how the spring, spacers, retaining plate fit into a recess in the slide. Mine doesn’t have the recess in the slide, though it does have a cast lifter that is fixed to the slide with screws, no steel plate. The fiche I can find for an A1 shows the spring and spacer setup.

All I have is the needle and clip sitting inside the slide with the lifter sitting over it. The needle isn’t well retained and can float up and down about 1/2 - 1 mm, which don’t seem right.

Can anyone tell me what’s supposed to be in there?

I’m fairly sure the carbs are the right ones for the bike. They had the factory spec needle and main jet in them anyway.

Thanks, Olly
'In your twenties you think you are immortal, in your thirties you hope you are immortal, in your forties you just hope it doesn't hurt too much'



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Re: Z1000A1 carb setup

#9 PostAuthor: zed1015 » Tue Jan 08, 2019 4:29 pm

Mr Bump wrote:
All I have is the needle and clip sitting inside the slide with the lifter sitting over it. The needle isn’t well retained and can float up and down about 1/2 - 1 mm, which don’t seem right.

Can anyone tell me what’s supposed to be in there?

Thanks, Olly


Just the Needle and clip is correct.
Nothing is missing.

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Re: Z1000A1 carb setup

#10 PostAuthor: DavidZ1R » Tue Jan 08, 2019 5:26 pm

[code][/code]
Think you must have a later a1 model, the earlier ones had the spring, as mind did, or its the other way round.
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Re: Z1000A1 carb setup

#11 PostAuthor: Mr Bump » Wed Jan 09, 2019 8:00 pm

That’s good and bad I guess. The carbs are assembled correctly, but that leaves me without a solution to that flippin flat spot.

I imagine the earlier a1’s didn’t have springs and spacer, this was then added to later A1’s and then A2’s. Makes me wonder why they needed to introduce the change. I might think about adding a fibre washer or an o ring to secure the needle more positively.

Or maybe buying some genuine needle jets to see if the keyster kits are at fault, which means taking the carbs off again. Meh.

Thanks for your help and advice.

Olly
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Re: Z1000A1 carb setup

#12 PostAuthor: Ultim8pc » Thu Jan 10, 2019 12:52 am

Sounds like you've tried most things.
Although it shouldn't make a difference, can you try it with the snorkel and a standard air filter?
I use Keyster kits in all my rebuilds and never had an issue. However, you say the needles are rough - can you post of PM me a photo.
Also, make sure you have a z1000 air filer not z900. They are slightly different in design and if the wrong one is fitted, you pass more (unfiltered) air than stock which can give a flat spot off idle.
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Re: Z1000A1 carb setup

#13 PostAuthor: kev edwards » Thu Jan 10, 2019 10:29 am

I am a bit late to this thread, i have just looked in my factory service manual and there is no spring under the needle clip, have you looked at the underneath of the lifter mechanisms to see if they are worn and allowing excess needle movement, you say you have a K&N, have you increased the pilot jets a size or two, i have a B2 thou and i run a Harris style exhaust, i had a flat spot off idle, so i increased my pilot jets to 20 which cured that part, had lean running at higher revs so went to 107.5 main, main needle is a 5CN7 on groove 3, pilot screws initially 1and 1/4 turns out which had to be tweaked slightly when color tunes were put in, now runs very well, your K&N may be the cause of the flat spot also as you have no snorkel this will factor in, my old A2 would not run properly without the snorkel on standard or near to standard jetting, if you have the snorkel put it back on and work from there.

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Re: Z1000A1 carb setup

#14 PostAuthor: Mr Bump » Mon Jan 14, 2019 9:28 am

Hi,

I’v Now taken all the needles out and the finish varies. The oem ones seem to have some sort of coating and the surface finish is very fine. The best of the brass keyster ones is very slightly rougher, you can feel the finish with yr finger nail (just). At least one is quite rough and the roughness is easy to feel with a fingernail.

I don’t have a standard filter or a snorkel, otherwise the 1st thing I’d do is fit them, I’m not convinced this is the issue as its seemingly richening up, not running lean. There isn’t wear on the underside of the lifter as it’s a steel bit, but I can see some witness marking on the zinc finish that was probably caused by the needle clip vibrating. I’ve put a small O ring above each needle clip to see if it’s a cheap fix, but I’m not convinced I’m going to be that lucky.

I’m very suspicious of the keyster needles, anyone know where I can get a genuine needle and genuine needle jets?

Thanks,

Olly
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Re: Z1000A1 carb setup

#15 PostAuthor: warren3200gt » Mon Jan 14, 2019 10:29 am

Allens should be able to sort you out with genuine parts.
http://www.allensperformance.co.uk/shop/
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