Question about 2003 kawasaki KX 125

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I have a 2003 kx 125 and I cant seem to get the jetting right. I keep fouling plugs. My current carb settings are # 35 pilot jet, # 410 main , 2nd clip position from the top of my jett needle and air screw has been adjusted in many different positions. When I start the bike lots of white smoke is visible and I bogg out in mud and hill climbs. I find that at smaller throttle openings is where I foul the most plugs. my fuel ratio is 32:1. Thanks for the help. G

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If your still fouling plugs then you still need to go with smaller # on main jet...are you spooging allot out of pipe and muffler? then your to rich still,smaller jet size!!!! 32:1 is a good mix ratio

Posted on Sep 27, 2010


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1 Answer

What is the size of main jet of YZ125?

  • Main Jet: 410
  • Main Air Jet: 2.5
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Jun 05, 2011 | 2003 Yamaha YZ 125

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Spark plug keeps blowing on my kx 100

if your fouling plugs then either your fuel/mix ratio is off ( should be mixing 32:1 ) (or) your bike is running to rich( getting to much fuel to engine) which means you need to rejet the carb....example:( if you have a #50 jet,you need a #48 or 49) to install a new jet, #1.)remove carb,#2.)remove the bowl(4-screws),you will see the jet and #3.)unscrew jet and replace with smaller # ( number is stamped on the jet.) you can get jets from local motorcycle dealer( but they will probably have to order them). or go online to enter your bikes year,make,model,ect.and just order from them........

Sep 27, 2010 | 2003 kawasaki KX 125

1 Answer

Pilot screw setting.

Stock it would be around 2 turns out.

These bikes shipped with only one jet needle (unlike other Yamaha's) the bike's factory jetting is 45 pilot, NBKF needle on the 2nd clip from the top, and 138 main. This bike tends to run a little rich off the bottom, so I'd recommend running a 42 pilot instead. When it's really hot out (over 90) you can run the 135 main jet.

Screwwing with carbs is fact of life with these bikes - you will have to do some tweaking no matter what. smile.gif

May 13, 2010 | 2003 Yamaha YZ 125

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Factory settings

Contact Kawasaki information ,or help team .Or find your nearest dealer and talk to there mechanics they should have manuals that are far more advance in information that normal ones .

Mar 12, 2010 | 2003 kawasaki KLX 400 R

1 Answer

What is the right Jet sitting for a Mikuni KX 125 Carburator 1987 Model?

It should have a #370A main jet in it. The pilot jet should be a #35. The jet needle should be a #R-2. The throttle screw setting is one and one half turns outward from a LIGHTLY seated position.

Nov 22, 2009 | 2003 kawasaki KX 125

2 Answers

My 87 yz 125 keeps fouling plugs can anyone help? It runs fine on a four stroke plug but is down on power as you can imagine but will also burn out my piston with long use mates have told me float levels...

Keep the correct plug in it.
If the plug looks black, it's due to too much fuel. You need to go smaller on your jetting. (You need to buy these at a dealer)
Your pilot jet will have a number on it. Get the number off of it and try a smaller step smaller. This effects your jetting from idle to 1/4 throttle.
The needle has a clip on it so you can raise the needle (lower the clip) up or down to effect your jetting 1/4 to 3/4 throttle.
The main jet also has a number on it, and this effects your jetting from 1/2 to full throttle.
Do your jetting by plug color. You don't want white (Lean) or black (Rich) You want chocolate brown.
Keep in mind that crank seals can screw up your mixture, as well as worn out rings, dirty air filter, or poor spark.

Oct 09, 2009 | 2003 Yamaha YZ 125

1 Answer

Need carb settings for a Husqvarna wr125 1999 model

Main Jet 400
Jet Needle 6DJ8-60
Jet Needle Groove - 3rd
Pilot Jet - 35
Idle air screw - 1+1/2
Slide 3.0

Free manual here...

Aug 04, 2009 | 2000 Husqvarna WR 125

1 Answer

Kx 85 04,bike had a slight bog when throttle was gassed then i cleaned the carb,now it really bogs and running very rich.i also messed with the air & idle screws hoping i could fix the problem &...

Start with setting the air and throttle screws. Turn each one inward until it GENTLY seats. Back each one out one and one half turns. Clean the air filter and starter plunger. The plunger may need to be rebuilt or replaced. Check the pilot and main jet sizes. There will be a number stamped on the side of the jets. The pilot jet should be #45, the main jet should be #140.

Aug 01, 2009 | 2004 kawasaki KX 125

1 Answer

Engine not running

Your carb should have another jet. What you cleaned was the main jet in the center of the carb. There should be another jet called a pilot jet. Often it has a metal plug covering it up so the setting can not be changed at that point. Instead, they want you to change the setting with the pilot air screw. In each case, if you remove the screw, count the number of turns for removal and put the screw back the same number of turns.

The pilot jet controls the idle. It picks up gas from the float bowl then the gas gets metered by the jet and the air screw then passes through a circuit (drilled passageway), in the carb casing and comes out in the center of the carb close to the needle jet. You will need to get the jet and circuit cleaned.


Jul 08, 2009 | 2006 Derbi Senda SM 125 4T

1 Answer

Just wondering what could be causing flooding with my kx 125

Causes of flooding on your bike are:
  1. Float level set too high
  2. Too large a main jet, #420 std. ( 400 min, 470 max)
  3. restricted air flow / filter
  4. Pilot jet too large #40 std. (35 min, 45 max)
  5. Air screw set too lean
  6. Jet needle clip set too low on the needle

Jun 24, 2009 | 2003 kawasaki KX 125

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