carb help!

Old Dec 31, 2017 | 02:35 AM
  #1  
redklx's Avatar
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Default carb help!

2008 klx 250s, all stock

I think somethings wrong!
I turned the mixture screw out (left) about half a turn.

My bike starts pretty quick , runs good after its warmed up (on choke) ,

but heres the problem
ill the bike warm up on choke for about 3 mins, then after its warmed up I rev it steadily at 3000 rpm
it will sputter and sound like its dying AND the only way to fix it is to get it into gear drive around for a bit and it will go away
what the heck is going on?!

I'm pretty sure I put the intake and air carb boots on snug so there shouldn't be a leak.
and the throttle cable looks like it responds well , how do I know if the cable isn't adjusted well?
 

Last edited by redklx; Dec 31, 2017 at 02:40 AM.
Old Dec 31, 2017 | 09:37 AM
  #2  
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If your going to warm it up, it will take about 5-10 minutes, otherwise it is ...... cold.
 
Old Dec 31, 2017 | 12:14 PM
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Why did you turn the mixture screw were you getting popping from the exhaust? If the carb's never been messed with and still has the stock pilot. Changing to 38 or 40 will help with starting and it will warm up a bit quicker.
 
Old Dec 31, 2017 | 04:37 PM
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Originally Posted by klxnoobie
Why did you turn the mixture screw were you getting popping from the exhaust? If the carb's never been messed with and still has the stock pilot. Changing to 38 or 40 will help with starting and it will warm up a bit quicker.
yeah I was getting a lot of decel pop.

which one is the pilot screw?
 
Old Dec 31, 2017 | 04:39 PM
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Originally Posted by durielk
If your going to warm it up, it will take about 5-10 minutes, otherwise it is ...... cold.
hold the choke for 10 min ! ?

that seems long ...
ill try letting it warm up with the choke and then idle for longer.
 
Old Dec 31, 2017 | 08:03 PM
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You got the idle mix a bit richer, but nothing else is richer. So it will idle better, but when it comes off the idle circuit it runs lean and wants to stall out. The reason why to do all the jetting work. My bike starts nearly instantly and in any weather over 50 degrees will be off choke in less than a minute and running fine. Jetted well works well. 1/4 of the job doesn't.
 
Old Dec 31, 2017 | 10:49 PM
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Originally Posted by horror_fan
yeah I was getting a lot of decel pop.

which one is the pilot screw?
If you hit up Dynojet web site you can dl the instructions which will help you identify the questions your asking. Kits 2152,2206 will help you out.

The one nice thing about the jet kit it identifies the problems associated with the klx and has info on how to dial in the fuel mixture screw. Which is why some owners justify going up on the pilot jet 38 and sometimes 40 as I had done in so cal. The technical assistance phone line can help you even more....
 

Last edited by RaceGass; Dec 31, 2017 at 10:54 PM.
Old Jan 2, 2018 | 09:52 PM
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Originally Posted by RaceGass
If you hit up Dynojet web site you can dl the instructions which will help you identify the questions your asking. Kits 2152,2206 will help you out.

The one nice thing about the jet kit it identifies the problems associated with the klx and has info on how to dial in the fuel mixture screw. Which is why some owners justify going up on the pilot jet 38 and sometimes 40 as I had done in so cal. The technical assistance phone line can help you even more....


what about the 38 size jet from this website ?
https://www.jetsrus.com/a_jet_kit_di...50_KLX250S.htm

are they'r any sites you recommend for just a single pilot jet?

also does the dyno jet kit come with different combos of jets?
 
Old Jan 2, 2018 | 11:45 PM
  #9  
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Originally Posted by horror_fan
what about the 38 size jet from this website ?
https://www.jetsrus.com/a_jet_kit_di...50_KLX250S.htm

are they'r any sites you recommend for just a single pilot jet?

also does the dyno jet kit come with different combos of jets?
Jetsrus is my go to site. No issues and quick shipping.

The dyno jet kit comes with I believe 4 different main jets. 120 , 124 , 128 , 132
 
Old Jan 3, 2018 | 05:31 AM
  #10  
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Originally Posted by klx678
You got the idle mix a bit richer, but nothing else is richer. So it will idle better, but when it comes off the idle circuit it runs lean and wants to stall out. The reason why to do all the jetting work. My bike starts nearly instantly and in any weather over 50 degrees will be off choke in less than a minute and running fine. Jetted well works well. 1/4 of the job doesn't.

okay lets see if I'm understanding this correctly
  • Pilot Jet - this controls the amount of fuel when idling
  • Main Jet - this controls the fuel when you open up the throttle (between 50 and 100 percent power)
and based off that intuition my plan should be:
1) adjust the mixture screw back to stock
2) get one size bigger pilot
3) get one size bigger main

1) b/c its over richened during warm up
2) b/c I want better starting and smooth warm up?
3) to fix the lean-ness at higher speeds
 

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