Idle issues

[apwcu]

New here, just bought a 93 Fzr600 with 11,000 miles in pretty good shape. The bike runs and rides perfect but it will not idle. The previous owner said he cleaned the carbs 3 times and still couldn't get it to idle. It gets better when the bike warms up but it will idle down to about 800 then stall.

Where do I need to start looking? The bike is completely stock also and it seems to run just a little rich.

Thanks


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[pnbell]

First; did you try to adjust the idle speed yet?

*The Idle Adjustment screw is a Tiny Knob near the Fuel Petcock (have to reach your hand inside the fairing in front of the fuel petcock). Turning it clockwise raises the idle.

Why do you think it is running Rich?

let us know.

[apwcu]

I was going to try and adjust the idle this evening. You can smell fuel pretty good
If you are standing behind it and if you rev it really good it will smoke just a bit.


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[pnbell]

You might consider Checking/Cleaning the Sparkplugs. Its amazing how much clean spark plugs help.

But first adjust the idle and let us know.. its easy.. i do it a stop lights often...

[apwcu]

Ok, I'll try that and report back. He also mentioned it had new plugs because he kept getting them soaked in fuel. I think he showed me that screw and was saying it was a mixture screw and if you adjusted out any higher the bike will rev higher and hang when you shift.



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[pnbell]

I think he showed me that screw and was saying it was a mixture screw and if you adjusted out any higher the bike will rev higher and hang when you shift.

That is interesting as we just discussed this "Hanging RPM" in a post viewtopic.php?f=8&t=9590 about erratic idle. The problem was Intake Leaks causing inconsistent airflow.

Anyway, if what he showed you was a single knob that you could grab with your hand; it was the idle adjustment screw. When the bike is at operating temperature you Need to set your idle using this screw to about 1,200 rpm.

Now if the bike is 'Hanging' before it comes back down to 1,200rpm, then you very well might have a vacuum leak and/or need to tune the Air/Fuel mixture screws. * Again refer to the link i posted above.

NOTE: The Mixture screws are actually on the carbs; there are 4 of them.. They are used to control the mixture of Fuel/Air the Pilot jet supplies the engine. -It's very possible that you'll have to tune these on your bike; But first you would have to Set the Idle correctly, Identify if you have any Vacuum Leaks, and Sync the Carbs.

[apwcu]

I forgot to mention that he told me he thought the problem was the diaphragm sliders in the tops of the carbs.

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[apwcu]

Well I messed with the idle screw and all that did was make it hang even worse between shifts. Where should I start looking for vacuum leaks?
Would unsynchronized carbs cause this? The bike does run very well, even if you're coasting and pull the clutch in the bike will sit around 1100 and won't die.

Thanks for the help.

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[pnbell]

The most common Vacuum Leak area is the Intake Boots. Basically pull the gas tank out of the bike, set in on a stool next to the bike, start the bike, and spray Starter Fluid around the intake boots. If the RPMs increase while doing this you have a Vacuum leak in the Intake Boots. Either they are Not Sealing or Cracked. I just replaced mine the other day. (perform this while the bike is warm)

Again see the link i posted above.

Once you check the intake boots as described, the next steps would be Syncing Carbs and Adjusting Mixture Screws.

Again see the link i posted above... Haha

[buzzawak]

Correct me if I am wrong, but isn't starter fluid flammable ?
Maybe some thing like WD40 would be a bit safer and achieve the same results.

The most common Vacuum Leak area is the Intake Boots. Basically pull the gas tank out of the bike, set in on a stool next to the bike, start the bike, and spray Starter Fluid around the intake boots. If the RPMs increase while doing this you have a Vacuum leak in the Intake Boots. Either they are Not Sealing or Cracked. I just replaced mine the other day. (perform this while the bike is warm)

Again see the link i posted above.

Once you check the intake boots as described, the next steps would be Syncing Carbs and Adjusting Mixture Screws.

Again see the link i posted above... Haha

[pnbell]

Yea, it's flammable.. That's the Point! Ha ha!!

I mean we're not spraying it into an open flame, and very little spray is needed for the test. But i mean basically this is the intended purpose of Starter Fluid...

[apwcu]

Well I tried the starting fluid and I didn't notice any change in idle. I may try synching the carbs, is it hard to do?

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[pnbell]

Well I tried the starting fluid and I didn't notice any change in idle. I may try synching the carbs, is it hard to do?

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Not really, just need the right tool.