KPX Idle??

Bill Hilly · 11-10-2023, 01:55 PM

Idle gets a little rough after idling for a short while. I can start my bike, and it will idle real smooth, but after it idled for a while with the throttle not being touched, the idle gets kinda choppy, it goes up just a little, and back down a little, but still staying in the 1400-1500 range on the tach, basically just like one bar coming, and going on the tach. I have sent my ECU in already, and the bike takes throttle fine. I can ride it , come to a stop light, and it will idle real smooth at first, and then get choppy. Is this normal? Will your bike just sit and idle perfectly smooth as long as you please, or does it act like mine?

**JerryHawk250** · 11-10-2023, 02:13 PM

Have you tried adjusting the throttle position sensor? I know you have messed with it before you sent the ECU in.

Bill Hilly · 11-10-2023, 02:19 PM

Quote:

Originally Posted by JerryHawk250

Have you tried adjusting the throttle position sensor? I know you have messed with it before you sent the ECU in.

I put it back to were it was when I got it, which is basically all the way counterclockwise. It's hard to see, but they have their position marked with a blue marker. . I may experiment with it. I just thought it may be normal for them to kind of go up, and down a little in regulating idle speed.

herbie · 11-10-2023, 02:34 PM

Personally I think that is pretty normal for them to do.

Thumper · 11-10-2023, 02:57 PM

On my carbed bike, I can adjust idle so easily. The simple slide height adjustment is SO nice to have. An the big knob makes them easy to adjust even with a glove on. Check it out:

https://www.chinariders.net/showpost...80&postcount=6

Click image for larger version

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I wonder if EFI bikes let you do this. Is there an idle adjustment? I know they are made to be fully automated, but I had similar issues with my Suzuki 1250 EFI bandit, but only if I used the switch on the handlebar to turn it off temporarily. It got confused, and had to be reset by turning the key off/on.

Maybe this kind of "confusion" is what is going on with these single cylinder EFI systems.

My old 70s GS series Suzukis had an idle adjuster accessible in the middle behind the cylinders, my 80s GS series 850 and 1100 shafties had CV carbs with the same idle adjusters. It was easy to put the idle where you wanted it.

Then there are the EFI gremlins that show up here. Sure, it is "rare", but holy cow, I would hate to be that one poor guy that gets stung with an EFI failure.

Analog air/gas mixing might seem primitive, but it is easy to fix if it gets wonky. Clean the carb, adjust it, no mystery!

Do©Hawk · 11-10-2023, 04:20 PM

My Hawk DLX idle fluctuates similarly up and down by a bar on display. I had some slop in my throttle cable that I adjusted out. It made no difference in the idle fluctuation, but made a world of difference with throttle response.

Bill Hilly · 11-10-2023, 04:36 PM

Quote:

My Hawk DLX idle fluctuates similarly up and down by a bar on display. I had some slop in my throttle cable that I adjusted out. It made no difference in the idle fluctuation, but made a world of difference with throttle response.

That's basically how mine does. Each bar evidently represents 200 rpm, and mine will idle with 2 bars past the 1,000 , then flash the third, and then back to 2 bars momentarily, then flash the 3rd. But it idles smooth, and a little faster while warming up, and then it starts the above mentioned cycle. It also idles smooth, and nice, and just a hair faster breifly after the throttle had been used.

Bill Hilly · 11-10-2023, 06:15 PM

I took the side cover to see if maybe the air filter wasn't sealed good, and I saw this on a nipple right on top of the airbox. It's been letting my motor draw unfiltered air through it for almost 500 miles. It's hard to tell what it's did to my cylinder walls, and rings. It looked like a hose had been cut off of it, but I think it's probably supposed to be rounded on the end, but mine was defective. The end is thin like a balloon, and has a hole in it it also has a tear in the side were,I suspect the hard plastic nipple on the airbox probably went through it from being forced on with the end collapsed due to being so thin. I will get, or make a plug tomorrow, but it seems like it probably helped the idle. I could just barely get a pinky finger in there sideways to block it, but it seems like it was idleing better, but it may just not got warm enough to start fluctuating.
http://

upload

11-10-2023, 01:55 PM	#1
Bill Hilly Join Date: Feb 2021 Posts: 934	KPX Idle?? Idle gets a little rough after idling for a short while. I can start my bike, and it will idle real smooth, but after it idled for a while with the throttle not being touched, the idle gets kinda choppy, it goes up just a little, and back down a little, but still staying in the 1400-1500 range on the tach, basically just like one bar coming, and going on the tach. I have sent my ECU in already, and the bike takes throttle fine. I can ride it , come to a stop light, and it will idle real smooth at first, and then get choppy. Is this normal? Will your bike just sit and idle perfectly smooth as long as you please, or does it act like mine?
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11-10-2023, 02:13 PM	#2
JerryHawk250 Moderator Join Date: Oct 2016 Location: Houma, La. Posts: 11,561	Have you tried adjusting the throttle position sensor? I know you have messed with it before you sent the ECU in. __________________ 2023 Lifan Lycan 250 Chopper 2023 Venom Evader 2022 Lifan KPX250 2020 Kawasaki Vulcan S 2004 Honda ST 1300 2016 Black Hawk 250 (sold) Keihin PE30 carb,125 main,38 slow.Pod filter,ported & decked head 10:1 CR,Direct Ignition Coil,15/40Sprockets,NGK DPR8EIX-9,De-Cat,Dual Oil Cooler,Digital Cluster 2016 Cazador180 XL 2014 Coolster150 JerryHawk250.com My YouTube Channel
	1

11-10-2023, 02:34 PM	#4
herbie Join Date: May 2019 Location: Illinois Posts: 864	Personally I think that is pretty normal for them to do. __________________ 2022 Venom KPR 200 Red- the fastest color 16t and 46t sprockets, NGK Iridium CPR8EAIX-9, aftermarket full exhaust system. Top speed 81GPS 2023 Venom SS3 KP mini 150– Nibbi carb, Nibbi air filter, aftermarket muffler, decat 2022 Venom Ghost chopper 250 1997 Honda GL1500 Goldwing 1978 Kawasaki KL250 https://youtube.com/@herbiesgarage681
	1

11-10-2023, 02:57 PM	#5
Thumper Join Date: Feb 2021 Location: Kansas City Posts: 2,318	On my carbed bike, I can adjust idle so easily. The simple slide height adjustment is SO nice to have. An the big knob makes them easy to adjust even with a glove on. Check it out: https://www.chinariders.net/showpost...80&postcount=6 I wonder if EFI bikes let you do this. Is there an idle adjustment? I know they are made to be fully automated, but I had similar issues with my Suzuki 1250 EFI bandit, but only if I used the switch on the handlebar to turn it off temporarily. It got confused, and had to be reset by turning the key off/on. Maybe this kind of "confusion" is what is going on with these single cylinder EFI systems. My old 70s GS series Suzukis had an idle adjuster accessible in the middle behind the cylinders, my 80s GS series 850 and 1100 shafties had CV carbs with the same idle adjusters. It was easy to put the idle where you wanted it. Then there are the EFI gremlins that show up here. Sure, it is "rare", but holy cow, I would hate to be that one poor guy that gets stung with an EFI failure. Analog air/gas mixing might seem primitive, but it is easy to fix if it gets wonky. Clean the carb, adjust it, no mystery! __________________ -2022 5 speed Templar X Orange, OEM 51T rear sprocket, 14T front sprocket -NOS 2020 KTM 250SX (2-stroke motocross), less than 10 hours on it Last edited by Thumper; 11-10-2023 at 04:28 PM.
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11-10-2023, 04:20 PM	#6
Do©Hawk Join Date: Oct 2023 Location: Western PA Posts: 195	My Hawk DLX idle fluctuates similarly up and down by a bar on display. I had some slop in my throttle cable that I adjusted out. It made no difference in the idle fluctuation, but made a world of difference with throttle response. __________________ 2022 Hawk DLX EFI * 17T Front / 47T Rear / upgraded chain * Kenda K-760 front + rear * Banjo brake light switch * LED headlight + front turn signals * Debadged (I don't like to brag about the superior strength!) * Top speed, GPS verified, as equipped: 68 mph (so far)
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11-10-2023, 06:15 PM	#8
Bill Hilly Join Date: Feb 2021 Posts: 934	I took the side cover to see if maybe the air filter wasn't sealed good, and I saw this on a nipple right on top of the airbox. It's been letting my motor draw unfiltered air through it for almost 500 miles. It's hard to tell what it's did to my cylinder walls, and rings. It looked like a hose had been cut off of it, but I think it's probably supposed to be rounded on the end, but mine was defective. The end is thin like a balloon, and has a hole in it it also has a tear in the side were,I suspect the hard plastic nipple on the airbox probably went through it from being forced on with the end collapsed due to being so thin. I will get, or make a plug tomorrow, but it seems like it probably helped the idle. I could just barely get a pinky finger in there sideways to block it, but it seems like it was idleing better, but it may just not got warm enough to start fluctuating. http:// upload Last edited by Bill Hilly; 11-10-2023 at 06:27 PM. Reason: Forgot picture
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