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Discussion Starter · #1 ·
I just finished disassembling, cleaning, and reassembling the carburetors on my ’02 ZX-9R, after they got gummed up from sitting too long with old gasoline. I mounted the carbs back on the bike and started it up, but now the bike “idles” at 8,000 rpm with the choke off! The idle speed is constant, meaning it doesn’t dip and jump on its own. If I open the throttle the idle speed increases, and when I close the throttle it returns to 8,000 rpm.

The butterflies are closed so it doesn’t appear that there is a problem with the throttle cable adjustment or that it’s sticking, the choke assembly opens and closes properly so it doesn’t appear that there is a problem with the choke. Pilot screw adjustments made no difference. The carbs and parts are stock, not aftermarket. Any suggestions?
 

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Checked any vacuum hoses, needle clip position. If you split the carbs didn't leave any "O" rings out?
gammac
 

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Discussion Starter · #3 ·
The only hoses connected to the carbs are the air vent and fuel hoses. The needles for these carbs do not have adjustable clips, they’re one position only. No o-rings were left out.
 

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I have a similar problems now that I rebuilt my carbs. I'm pretty sure it's the pilot screw settings. I tired to put them all at 7/4 turns out, but 1/8 turn deviation in either direction is huge. My bike now idles at about 2000 rpm, any less and it'll stall. I'm sure some screws are in too far and some out. I'm going to have the carbs synced when I get the valve clearances checked.
 

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I just cleaned mine, but I removed the carbs as an assembly. One thing I noticed reassembling the carbs to the intake was how easy it could be not to seat them properly. I used a small mirror to check they were pushed down all the way.
 

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Sounds like air is getting by the carbs.
Try this....
Start the bike. Liberally squirt quick shots of brake parks clear around the intake boots (where the carbs go into the boots).
If air is getting by then engine speed will change do to the spray.
If it does, then you know that the carbs aren’t seated right.
Good luck.
 

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I just finished disassembling, cleaning, and reassembling the carburetors on my ’02 ZX-9R, after they got gummed up from sitting too long with old gasoline. I mounted the carbs back on the bike and started it up, but now the bike “idles” at 8,000 rpm with the choke off! The idle speed is constant, meaning it doesn’t dip and jump on its own. If I open the throttle the idle speed increases, and when I close the throttle it returns to 8,000 rpm.

The butterflies are closed so it doesn’t appear that there is a problem with the throttle cable adjustment or that it’s sticking, the choke assembly opens and closes properly so it doesn’t appear that there is a problem with the choke. Pilot screw adjustments made no difference. The carbs and parts are stock, not aftermarket. Any suggestions?
Not knowing exactly what all you went through and replaced, the idea that too much intake air will up the rpm doesn't hold water. For the idle to run up to 8K, you have to be getting excess FUEL which will cause the motor to pull air. Sounds like the enrichener circuit is not shutting off as it should when the lever is in the closed position. Also, some CV carbs have a large rubber o-ring on the main tube that can cause too much fuel flow if the ring is cracked or deteriorated. A good carb cleaning job should always include replacement of all soft parts such as float nedles, o-rings and gaskets.
 
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