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Discussion Starter #1
I have a question about my Idle Screw. I just recently bought a like new kfx450r and this weekend I took the bike out for a ride. While I was out riding I noticed that the bike started stalling out or breaking down. basically it just shut off during my ride. I jumped off and tool a closer look at the bike and noticed that the bike was running with the idle screw pulled out the same way you would pull your choke out on a carbuerated bike. I tried riding back to my truck and pushing the idle screw in but that made the bike totally break down as soon as my thumb was off the throttle later on I could start up the bike with the idle screw pulled out again. What do you make of this? I have the screw turned 24 clicks to the right I might mention.
 

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22 clicks is standard, but with my mods I was running about 16 to get the proper idle. The further clockwise you turn it the less air that bypasses the butterfly through the throttle body, meaning that your idle drops. Try turning it out a few clicks counter-clockwise, one at a time, and see if that helps. If it doesn't you most likely need to adjust your TPS.
 

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What does pulling the idle screw out and pushing it in do to the engine?
Also whats a tps lol?
Pull for cold starts, push in for normal running...like a choke on a carburetor...

Factory Idle is turn clockwise until it stops then back out counter-clockwise 22 clicks or 1800 RPMs standard speed

TPS short for throttle positioning sensor, that's on the shifter side of the throttle body...Your voltage @ close 0.58v~0.62 volts...standard...

you'll need it hooked up with a digital multimeter set at 25 DCV...positive lead to yellow wire...Negative to Brown wire...loosen the screw in order to move the TPS to the desired voltage...with the key on motor "not" running...

PM me if you want a service manual "Free" Download or purchase one at the bottom of my posting...

 

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What does pulling the idle screw out and pushing it in do to the engine?
Also whats a tps lol?
When you pull it out it allows even more air to pass through a bypass tube in the throttle body, increasing the idle by adding air but not fuel...leaning it out.

The TPS is the throttle position sensor which is located on the throttle body right next to the idle adjust knob. You have to check the voltage drop that is reading across the sensor at closed throttle by using a digital multi-meter. It should read .62-.64 volts at closed throttle.
 

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Discussion Starter #9
So my problem is the bike runs better with the choke open? Can I fix that issue if I buy a digital multi-meter and mess with the tps sensor? How much does a digital multi-meter cost?
 

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Discussion Starter #11
OK so I got around to tinkering with my quad today. I took the spark plug out to see if it needed to be changed. The bottom was black with soot so I changed it out for a new one. I was hoping that would fix the problem. No such luck. The bike will start perfectly with the idle screw out but will not work at all with the idle screw pushed in. Ive got it 22 clicks out. So I guess I'm off to Home Depot to but a digital multi-meter. Hope this fixes the problem
 

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Check for leaks around the throttle body boot and the vacuum hose to the air pressure sensor for cracks...

And check the TPS voltage @ close 0.58~0.62v standard..
 

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Discussion Starter #13
Ok so I just bought the multimeter. Do I just need to check the tps voltage on close? If that is good then I'm good there or should I test for something else?
 

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Discussion Starter #14
Also I've never used a multimeter. The one that I have has a dial with a bunch of measurements around it. For example: 2 20 200 600 and so on. Also I have to pick dc current measurement, ac voltage measurement, resistance measurement, diode test, battery and fuse replacement. Thanks for the help in advance.
 

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My kfx450r has its TPS at .566-.575 volts as reading on my power commander 5 program on my computer at idle. Is this too low? Do I spin the screw to turn this up? What should the the tps be set at for idle? I also know this is and old thread but feel like my power is off and could this be why?
 

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Are you reading input voltage or is that the actual tps voltage

Spec for the output it .58-.62
 

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Actual TPS voltage for me I'm below the .62 i would like to be at was wondering how to get there..
 

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You loosen the screw and turn the sensor.

It takes a few tries to get it perfect
 
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