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Discussion Starter #1
Hey all,

I've got an '87 ninja 600rx that I just bought and rode home two days ago. When I got home I went through the carbs and cleaned them out, and replaced the spark plugs. I was having issues starting it for two days, you couldn't even push start it. I finally got it started today and now I have a new problem.

I can't get it to idle at all, it goes straight to 4000rpm and sits there, choke on or off. I believe that the problem is related to the throttle cables because if i push the throttle grip all the way closed, the motor dies. There is some resistance when I try and roll on the throttle, then it clicks, and goes back up to 4000rpm. I tried adjusting the idle and it sits at the same place the whole time. I was just wondering if anybody has any similar experience and/or tips?
 

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second chimp in space
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3,344 Posts
Did you try messing with the main idle adjuster? My '87 ninja 750 has a knob on the left side of the carb rack that sets the lower limit of the main butterflies, essentially controlling idle speed. Clockwise = higher throttle, counterclockwise = lower throttle. Turning this clockwise has the same effect as twisting the grip ever so slightly.

Where did you put the idle screws? If memory serves right the 600 is 1.5 turns out. You did take this screw out along with the oring behind it before putting carb cleaner on the carbs, right? If that oring is cracked it will mess with your idle, but it wouldn't mess it up as much as you're describing.

I think your most likely problem, though, is that the cables are too tight. Where the throttle cable attaches to the carb, you can set the cable's slack with a nut. Make this obviously loose. I say this because you said that forcing the throttle closed (which uses another cable that you have to make sure also has enough slack) affects the idle. It shouldn't.

Also, make sure the whole cable is greased. You can get cable lube kits at auto parts stores where you plug up one end of the cable and shoot lube in until it comes out the other end. It worked great on my throttle cables which needed it after 17 years, like I bet yours do.
 

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second chimp in space
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Ooops. I checked in my book again and the zx 600rx (600B) has the pilot screw setting at 2 turns out from the factory.
 

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Discussion Starter #4
I'm new to this bike all together. Where is the pilot screw located? I won't be able to look at the bike until tomorrow morning, but if it's like my kz550...there is a small cover that needs to be drilled out.

Thanks for the suggestions, and I'll try what I can tomorrow, but I'm still replacing the cables because the throttle push cable is frayed and about to break anyway.
 

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second chimp in space
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The pilot screw is on the bottom of the engine side of the carb. The 750 has it plugged out of the factory, but I don't think the 600 does.

I wouldn't mess with that until you have the new cables though. There's a good chance that it won't be a problem. If you can't get a nice stable idle, then start looking at the pilot screws.

Good luck.
 

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I have a 90' 600R. Besides the cables check the throttle at the grip. If mine is not put back together just right it will do the same thing. Something inside sitcks. Not exactly sure what. I will just reasseble the same way several times than it is just fine.

Get a Clymer manual, they answer a lot of questions. Can save you $$$ in the long run on repairs you can do yourself.
 

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Discussion Starter #8
Thanks for all the help guys.

I figured it out the other day, when I reinstalled the carbs after I cleaned them the first time, I angled the clamp wrong on the rubber carb boots. The end of the screw was catching on the throttle mechanism causing it to "click and get stuck."

My new problem is how the previous owner jetted the bike. I ordered a K&N jet kit and I'm going to start over from scratch.
 
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