Idling way to high

D1rtyBird3 · 03-22-2024, 11:26 PM

I put a new Nibbi PE30 carburetor with #40 pilot jet and #140 main jet and a pod filter on my bike and when I start it, it idles extremely high. When adjusting the idle screw, I have to back it almost all the way out for the idle to come down just a little and the pilot screw has to be backed out 1/8th turn. I’ve tried adjusting the throttle cable, even took the throttle off the carb to make sure the slide sits all the way down and nothing changed. Engine gets hot very fast and the exhaust was glowing red at one point. Not sure what to do? Any ideas?

Thumper · 03-23-2024, 02:11 AM

Quote:

Originally Posted by D1rtyBird3

I put a new Nibbi PE30 carburetor with #40 pilot jet and #140 main jet and a pod filter on my bike and when I start it, it idles extremely high. When adjusting the idle screw, I have to back it almost all the way out for the idle to come down just a little and the pilot screw has to be backed out 1/8th turn. I’ve tried adjusting the throttle cable, even took the throttle off the carb to make sure the slide sits all the way down and nothing changed. Engine gets hot very fast and the exhaust was glowing red at one point. Not sure what to do? Any ideas?

What brand/model did you install this carb on?

D1rtyBird3 · 03-23-2024, 06:44 AM

Quote:

Originally Posted by Thumper

What brand/model did you install this carb on?

It’s a Xmotos XB88

superjocko · 03-23-2024, 05:41 AM

Does the engine speed up even more if you turn the handlebars to the right? If so, there's a good chance there isn't enough slack in your throttle cable to allow the carburetor slide to come down against the idle speed screw.

D1rtyBird3 · 03-23-2024, 06:45 AM

Quote:

Originally Posted by superjocko

Does the engine speed up even more if you turn the handlebars to the right? If so, there's a good chance there isn't enough slack in your throttle cable to allow the carburetor slide to come down against the idle speed screw.

I even took the throttle cable off to make sure the slide is all the down

**JerryHawk250** · 03-23-2024, 07:15 AM

The slide is probably installed backwards. Look to see if the slides all the way closed. If not, take it out and rotate it 180°

D1rtyBird3 · 03-23-2024, 07:31 AM

Quote:

Originally Posted by JerryHawk250

The slide is probably installed backwards. Look to see if the slides all the way closed. If not, take it out and rotate it 180°

It is all the way closed

D1rtyBird3 · 03-23-2024, 10:09 AM

Quote:

Originally Posted by JerryHawk250

The slide is probably installed backwards. Look to see if the slides all the way closed. If not, take it out and rotate it 180°

The slide will only go in one way, I tried to adjust the throttle cable to see if it was getting hung up and nothing changed. I took the throttle cable completely out of the carb so the slide definitely sits all the way down and the Idle is still really high. turning the idle screw counter clockwise does hardly anything until its almost all the way out. Turning the pilot screw clockwise does nothing until its 1/8th turn out.

Thumper · 03-23-2024, 10:32 AM

The symptoms do suggest stuck slide, and I thought that you cannot even screw on the cap to close the tower if the tab isn't aligned with the slot in the slide tower.
I believe what you are saying, the only thing I can think of causing high idle is the slide not closing all the way.
I don't think an air leak or airscrew could cause a high idle. You jetting seems in the ball park, certainly the pilot (#40). Maybe, just maybe try a #42 ??

I've gotta vote with Jerry on the slide though. It's the elephant in the room

TominMO · 03-23-2024, 08:25 AM

For reference:
https://www.xmotos.cz/gb/motorcycles...c-4t-2118.html

D1rtyBird3 · 03-23-2024, 10:03 AM

Quote:

Originally Posted by TominMO

For reference:
https://www.xmotos.cz/gb/motorcycles...c-4t-2118.html

Yes

buzz · 03-23-2024, 11:09 AM

My thought is put old carburetor back on, and see what happens. Bet it will work,it did before .

D1rtyBird3 · 03-23-2024, 12:00 PM

Quote:

Originally Posted by buzz

My thought is put old carburetor back on, and see what happens. Bet it will work,it did before .

The old (stock) carb would only work if the choke was on, like it wasn't getting enough air and would stall when you took off choke. It also wasn't serviceable, the bowl was held on with rivets so I had to get a new carb

J4Fun · 03-23-2024, 12:46 PM

Quote:

Originally Posted by D1rtyBird3

I put a new Nibbi PE30 carburetor with #40 pilot jet and #140 main jet and a pod filter on my bike and when I start it, it idles extremely high. When adjusting the idle screw, I have to back it almost all the way out for the idle to come down just a little and the pilot screw has to be backed out 1/8th turn. I’ve tried adjusting the throttle cable, even took the throttle off the carb to make sure the slide sits all the way down and nothing changed. Engine gets hot very fast and the exhaust was glowing red at one point. Not sure what to do? Any ideas?

Two questions, what’s the rpm of this high idle and are your valves adjusted correctly? I was concerned about that glowing red exhaust.

D1rtyBird3 · 03-23-2024, 02:25 PM

Quote:

Originally Posted by J4Fun

Two questions, what’s the rpm of this high idle and are your valves adjusted correctly? I was concerned about that glowing red exhaust.

I was thinking about lookin in to the valves, but that's way out of my league. as far as the RPM there is no tach so idk the exact RPM

03-23-2024, 07:15 AM	#6
JerryHawk250 Moderator Join Date: Oct 2016 Location: Houma, La. Posts: 11,713	The slide is probably installed backwards. Look to see if the slides all the way closed. If not, take it out and rotate it 180° __________________ 2024 Linhai 300 ATV 4x4 2023 Lifan Lycan 250 Chopper 2023 Venom Evader 2022 Lifan KPX250 2020 Kawasaki Vulcan S (Sold) 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
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03-23-2024, 10:32 AM	#9
Thumper Join Date: Feb 2021 Location: Kansas City Posts: 2,733	The symptoms do suggest stuck slide, and I thought that you cannot even screw on the cap to close the tower if the tab isn't aligned with the slot in the slide tower. I believe what you are saying, the only thing I can think of causing high idle is the slide not closing all the way. I don't think an air leak or airscrew could cause a high idle. You jetting seems in the ball park, certainly the pilot (#40). Maybe, just maybe try a #42 ?? I've gotta vote with Jerry on the slide though. It's the elephant in the room __________________ No matter where you go, there you are
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03-23-2024, 08:25 AM	#10
TominMO Join Date: Sep 2021 Location: De Soto, MO Posts: 1,976	For reference: https://www.xmotos.cz/gb/motorcycles...c-4t-2118.html __________________ 2021 Lifan Xpect--sold 2022 Lifan KPX 1972 Honda CT90--The Carrot 1969 Honda CT90--The Tomahto Cheesy is the WDK (workplace drama king). Now retired. Nope, back in the saddle. Nope, finally retired. Climate: The Movie https://www.youtube.com/watch?v=A24fWmNA6lM How our government really works https://www.youtube.com/watch?v=QjadCd0VRBw Question all authority.....think for yourself
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03-22-2024, 11:26 PM	#1
D1rtyBird3 Join Date: Mar 2024 Location: Central FL Posts: 11	Idling way to high I put a new Nibbi PE30 carburetor with #40 pilot jet and #140 main jet and a pod filter on my bike and when I start it, it idles extremely high. When adjusting the idle screw, I have to back it almost all the way out for the idle to come down just a little and the pilot screw has to be backed out 1/8th turn. I’ve tried adjusting the throttle cable, even took the throttle off the carb to make sure the slide sits all the way down and nothing changed. Engine gets hot very fast and the exhaust was glowing red at one point. Not sure what to do? Any ideas?
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03-23-2024, 05:41 AM	#4
superjocko Join Date: Aug 2022 Location: Lincoln CA Posts: 134	Does the engine speed up even more if you turn the handlebars to the right? If so, there's a good chance there isn't enough slack in your throttle cable to allow the carburetor slide to come down against the idle speed screw. __________________ -2024 CSC TT250, stage 3 motocult kit, Nibbi PE28FL with custom-made cable controlled choke, modified stock muffler (larger diameter tailpipe), custom oil cooler installation with relocated stock evaporative emissions canister, oversized stainless steel footpegs, IMS folding tip shifter, a few little blingy bolts and bits. More personal preference mods to come.
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03-23-2024, 11:09 AM	#12
buzz Join Date: Dec 2020 Location: Dayton Pa. Posts: 953	My thought is put old carburetor back on, and see what happens. Bet it will work,it did before .
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