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Z900 stumble just off idle

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Pauldonjuan
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Z900 stumble just off idle

#1 PostAuthor: Pauldonjuan » Sun Jun 23, 2019 3:37 pm

I have a us Z900 It stumbles just off idle, apart from that it runs perfect an clean. Done valve clearances, timing, carbs are clean, float levels set, balanced and pilots screws set. It's stock airbox and filter with the four pipes. I fitted the air corrector jets and that improved it. I know this is a common problem, can anyone tell me the cure?
Cheers

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zed1015
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Re: Z900 stumble just off idle

#2 PostAuthor: zed1015 » Sun Jun 23, 2019 7:44 pm

Ride the bike and feather the choke at the flat spot to see if that smooths it out.
Do it in a high gear 4th/5th as this is where you will feel the difference.
If it does you are still slightly lean coming off the pilot and richening on the air screw by 1/8 to 1/4 turn should do the trick.
You could also lift the needle a notch instead but it shouldn't need it on a stock air box set up.
US bike are set lean for emissions so maybe you need to go up a size on the pilot.
With a stock air box etc you shouldn't need the air correctors so those may need removing if going up on the pilot or lifting the needles.

Pauldonjuan
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Posts: 72
Joined: 2nd Mar 2017
Location: Southpor

Re: Z900 stumble just off idle

#3 PostAuthor: Pauldonjuan » Mon Jun 24, 2019 6:43 am

Hey Rob,
Thanks for the info, I'll try the feathering the choke on, I hadn't thought of that, I'm sure it'll confirm it's a lean issue I have. Hopefully I'll have it running sweet soon.
Can you recommend a guy for pilot jets? I usually use PDQ for jets.
Cheers.

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zed1015
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Re: Z900 stumble just off idle

#4 PostAuthor: zed1015 » Mon Jun 24, 2019 11:42 am

I think Allens performance should sell the pilots or someone on the forum may have the size you will need.
Apart from getting blocked they don't wear out so s/h ones will be good enough.

Pauldonjuan
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Joined: 2nd Mar 2017
Location: Southpor

Re: Z900 stumble just off idle

#5 PostAuthor: Pauldonjuan » Sun Jun 30, 2019 2:16 pm

Hey Rob,
After a bit more playing about, feathering in the choke made it worse. turned out the problem was running too rich, out with the air correctors and lean off the air screws an eighth at a time (2 1/8 out now) got it running sweet. Thanks for your input.
Cheers.


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