Background: Factory Pro (http://www.factorypro.com/tech/carbtun.html) documentation harps on the importance of selecting the proper Main Jet before modifying any other component in the carb system.
Selecting the proper Main Jet could take multiple iterations. Most riders are reluctant to do this because it requires significant time/effort.
Purpose: The purpose of this DIY/How-To is to describe in detail a method to swap Main Jets without carb removal. Bypassing carb removal will hopefully reduce time and effort so people are more willing to go through multiple iterations to find their best jetting.
I will try my best to be as precise as possible. But feel free to comment on any errors/imprecise verbage/lack of detail/etc.
I have already removed carbs once (http://www.kawiforums.com/showthread.php?t=111046 ... thanks Shade.Of.Black) to remove the idle mixture screw caps. I highly recommend this, because its necessary for proper jetting (this is later down the road though, we're on step 1 here) and is a good way to get familiar with the carbs.
Quick Details:
I. Drain Float Bowls
II. Remove Floats Bowls
III. Remove Main Jets
IV. Replace Main Jets
V. Re-install Float Bowls
VI. Prime Carbs
VII. Test
(Believe me, this is not an easy 7 step process)
Tools:
-Milwaukee Off-Set Screwdriver(herein referred to as MOSS) this is a MUST, this won't really work without it (http://www.kawiforums.com/showthread.php?p=1242367&highlight=milwaukee+off-set#post1242367 ...thanks 12013)
-Flexy/Bendy 1/4" bit shaft thing to get to pesky screws where a straight-shot isn't possible.
-1/4" bit handle to drive MOSS and bendy shaft
![Image]()
-3mm hex bit or Torx T15 (Torx is not the proper bit, but it worked better for me)
-#2 Phillips head bit (#2 phillips bit reall fits the float bowl screws the best)
-Flat head bit (I can't remember the size, but it should fit the slot on the Main Jet)
-8mm(preferred) or adjustable crescent wrench
-3/16" (or 4.5mm?) ID tube, I ganked mine from the Kleen Air system (http://www.kawiforums.com/showthread.php?t=112926 ... thanks kkim)
-Clean container to catch gas, should be able to hold as much as 8 ounces.
Orientation: Pretend your siting on the bike and looking down on the carbs.
Acronyms I will use:
MOSS Milwaukee Off-Set Screwdriver
FB Float Bowl
RSB From the Right Side of the Bike
LSB From the Left Side of the Bike
WYRH With Your Right Hand
WYLH With Your Left Hand
PITA Pain in the Ass
FP Factory Pro
Prep-Work:
-Remove the Side Covers, Seat, and Fairings (http://www.kawiforums.com/showthread.php?t=110849 ... thanks kkim)
-Take the signals from the fairings and zip tie them to the bike and plug them in (optional, I plan on jetting my bike with the fairings off so i can readily access the carbs)
-Take the idle adjustment knob off its holder on LSB. Bring it RSB and let it dangle in behind the clutch cover, its happy there while on the road. THe adjustment cable is a PITA when trying to remove the right FB.
Heads Up:
I don't have a digital camera easily accesible. But hopefully my instructions will be precise enough that you won't need any. However,I will refer to figures and pages from the service manual (maybe you cheap a$$es will buy one now =-)).
Getting to and working on the RSB carb is a PITA, so I always start with it first. Then the LSB is cake. Please perform this in a well ventillated area (Gas Fumes).
Detailed Steps:
I. Drain Float Bowls (Background: http://faq.ninja250.org/wiki/How_to_drain_the_float_bowls)
See Figure 3 of Page 3-15 for illustration.
1. Hook up the tube to the RSB FB and point it into the clean container.
2. Loosen the 3mm allen until fluid flows.
![Image]()
3. Close the allen once the FB is drained.
4. LSB, hook up the tube to the LSB FB and point it into the clean container.
![Image]()
5. RSB, loosen the 3mm allen until fluid flows.
6. Close the allen once the FB is drained.
7. Pour gas back into gas tank. (Thats why we use a clean container. Thats alot of gas to waste!)
II. Remove Floats Bowls (RSB)
1. Start with the outside screws of the RSB FB. RSB, use (MOSS + #2 Phillips + bit handle) to loosen the front screw.
![Image]()
2. There are about four wire bundles and the idle cable in the way of the rear screw. Pull them toward you to get them away from the screw, then spreas them apart with your fingers.
3. Use (bendy shaft + #2 Phillips + bit handle) to remove the rear screw.
4. LSB, remove the front screw with (MOSS + #2 Phillips + bit handle).
5. Support the FB WYLH. Remove the rear screw WYRH.
6. Be careful with the the FB. The spark plug looking thing below the RSB FB is a PITA and gets in the way. So, lower the FB slowly and tilt it forward and away from the carb.
7. Put RSB FB and screws aside aside in a clean area. The remaining gas on the FB is a magnet for dust/crap.
III. Remove Main Jets (RSB)
1. LSB, place the 8mm wrench or adjustable crescent wrench on the Needle Jet Holder (Item A on Figure 2 of Page 3-20). We don't want to loosen this when we loosen the Main Jet, otherwise the Needle Jet (Item A on Figure 1 of Page 3-20) will drop down.
![Image]()
2. RSB, use (MOSS + flathead + bit handle) to the loosen the pilot jet. If we loosen the Needle Jet Holder thats ok. We just don't want to fully unthread it, cuz the Needle Jet falling out is a PITA.
3. When trying to loosen the Main Jet. Use your off index finger to hold the MOSS from the top. MOSS has a notch at the top, which is brilliant, that gives you lateral control of the bit as well as allowing some axial pressure to be applied with the finger.
3. Unthread with your fingers, don't want the Main Jet to fall.
4. Remove the 8mm wrench or adjustable crescent wrench, we do not need it for tightening.
![Image]()
IV. Replace Main Jets (RSB)
1. Select the Main Jet from the FP kit.
2. RSB, carefully thread, WYLH, the Main Jet. All this stuff is brass; we don't want to bitch it up. So if it starts to bite, back it out and feel for the thread.
3. Finish by tightening the jet with (MOSS + flathead + bit handle). Finger tight should suffice, again its soft brass.
V. Re-install Float Bowls (RSB)
1. Make sure the FB is free of dirt/crap (I know you left it on the floor).
2. Prep (MOSS + #2 Phillips + bit handle) with one of the FB screws.
3. LSB, WYLH move the FB in front of that spark plug thingy.
4. Pivot the FB off the spark plug thingy, and raise it to the carb.
5. Make sure the FB is fully seated. The FB and carb are well indexed to each other, there shouldn't be any free play.
6. Slowly thread the rear screw WYRH. Don't fully engage or tighten.
7. Thread the front screw. Take up most of the slack. Don't tighten fully.
8. RSB, tread and tighten the front screw. Use a firm finger torque on the bit handle.
9. Use (bendy shaft + #2 Phillips + bit handle) to thread and tighten the rear screw. You probably have to move those cables out of the way again.
10. LSB, tighten the inside screws we almost completely threaded.
***Hard part is over! Lets move to the left carb. I promise its much easier.
II. Remove Floats Bowls (LSB)
1. Start with the inside screws of the LSB FB. LSB, use (MOSS + #2 Phillips + bit handle) to loosen the inside screws.
2. Remove the outside front screw.
3. Support the FB WYLH. Remove the outside rear screw WYRH.
4. Put RSB FB and screws aside aside in a clean area.
III. Remove Main Jets (LSB)
1. RSB, place the 8mm wrench or adjustable crescent wrench on the Needle Jet Holder.
2. LSB, use (MOSS + flathead + bit handle) to the loosen the Main Jet.
3. Unthread with your fingers, don't want the Main Jet to fall.
4. Remove the 8mm wrench or adjustable crescent wrench.
IV. Replace Main Jets (LSB)
1. Select the Main Jet from the FP kit.
2. LSB, carefully thread, WYRH, the Main Jet.
3. Finish by tightening the jet with (MOSS + flathead + bit handle).
V. Re-install Float Bowls (LSB)
1. Make sure the FB is free of dirt/crap.
2. Prep (MOSS + #2 Phillips + bit handle) with one of the FB screws.
3. LSB, WYLH raise the FB to the carb.
5. Make sure the FB is fully seated.
6. Slowly thread the outside rear screw WYRH. Don't fully engage or tighten.
7. Thread the outiside front screw. Take up most of the slack. Don't tighten fully.
8. Tread and tighten the inside screws
9. Tighten the outside screws we almost completely threaded.
***Told you it was eaiser! We're not done yet though.
VI. Prime Carbs
1. Turn the fuel petcock (Item A on Figure 1 of Page 3-26) to PRI. This will allow fuel to flow to the carbs without a vacuum present.
2. Open the gas tank to make sure the air pocket in the tank doesn't prevent the fuel from flowing.
VII. Test
1. Check your brain and make sure everything is connected and tight.
2. Check the FB is not leaking.
3. Fire it up.
4. Adjust the idle (remember we moved it to the right side of the bike) intially, just to the bike can run. You'll need to adjust it once the bike is warm.
DONE!
I hope this guide will help you in your forray into jetting. I was able to reduce my jet change down to 45 min!... on my second try! That means you can devote a solid sunday afternoon to finding the best Main Jet.
I will post my jet findings on this thread as I go.
Selecting the proper Main Jet could take multiple iterations. Most riders are reluctant to do this because it requires significant time/effort.
Purpose: The purpose of this DIY/How-To is to describe in detail a method to swap Main Jets without carb removal. Bypassing carb removal will hopefully reduce time and effort so people are more willing to go through multiple iterations to find their best jetting.
I will try my best to be as precise as possible. But feel free to comment on any errors/imprecise verbage/lack of detail/etc.
I have already removed carbs once (http://www.kawiforums.com/showthread.php?t=111046 ... thanks Shade.Of.Black) to remove the idle mixture screw caps. I highly recommend this, because its necessary for proper jetting (this is later down the road though, we're on step 1 here) and is a good way to get familiar with the carbs.
Quick Details:
I. Drain Float Bowls
II. Remove Floats Bowls
III. Remove Main Jets
IV. Replace Main Jets
V. Re-install Float Bowls
VI. Prime Carbs
VII. Test
(Believe me, this is not an easy 7 step process)
Tools:
-Milwaukee Off-Set Screwdriver(herein referred to as MOSS) this is a MUST, this won't really work without it (http://www.kawiforums.com/showthread.php?p=1242367&highlight=milwaukee+off-set#post1242367 ...thanks 12013)
-Flexy/Bendy 1/4" bit shaft thing to get to pesky screws where a straight-shot isn't possible.
-1/4" bit handle to drive MOSS and bendy shaft
-3mm hex bit or Torx T15 (Torx is not the proper bit, but it worked better for me)
-#2 Phillips head bit (#2 phillips bit reall fits the float bowl screws the best)
-Flat head bit (I can't remember the size, but it should fit the slot on the Main Jet)
-8mm(preferred) or adjustable crescent wrench
-3/16" (or 4.5mm?) ID tube, I ganked mine from the Kleen Air system (http://www.kawiforums.com/showthread.php?t=112926 ... thanks kkim)
-Clean container to catch gas, should be able to hold as much as 8 ounces.
Orientation: Pretend your siting on the bike and looking down on the carbs.
Acronyms I will use:
MOSS Milwaukee Off-Set Screwdriver
FB Float Bowl
RSB From the Right Side of the Bike
LSB From the Left Side of the Bike
WYRH With Your Right Hand
WYLH With Your Left Hand
PITA Pain in the Ass
FP Factory Pro
Prep-Work:
-Remove the Side Covers, Seat, and Fairings (http://www.kawiforums.com/showthread.php?t=110849 ... thanks kkim)
-Take the signals from the fairings and zip tie them to the bike and plug them in (optional, I plan on jetting my bike with the fairings off so i can readily access the carbs)
-Take the idle adjustment knob off its holder on LSB. Bring it RSB and let it dangle in behind the clutch cover, its happy there while on the road. THe adjustment cable is a PITA when trying to remove the right FB.
Heads Up:
I don't have a digital camera easily accesible. But hopefully my instructions will be precise enough that you won't need any. However,I will refer to figures and pages from the service manual (maybe you cheap a$$es will buy one now =-)).
Getting to and working on the RSB carb is a PITA, so I always start with it first. Then the LSB is cake. Please perform this in a well ventillated area (Gas Fumes).
Detailed Steps:
I. Drain Float Bowls (Background: http://faq.ninja250.org/wiki/How_to_drain_the_float_bowls)
See Figure 3 of Page 3-15 for illustration.
1. Hook up the tube to the RSB FB and point it into the clean container.
2. Loosen the 3mm allen until fluid flows.
3. Close the allen once the FB is drained.
4. LSB, hook up the tube to the LSB FB and point it into the clean container.
5. RSB, loosen the 3mm allen until fluid flows.
6. Close the allen once the FB is drained.
7. Pour gas back into gas tank. (Thats why we use a clean container. Thats alot of gas to waste!)
II. Remove Floats Bowls (RSB)
1. Start with the outside screws of the RSB FB. RSB, use (MOSS + #2 Phillips + bit handle) to loosen the front screw.
2. There are about four wire bundles and the idle cable in the way of the rear screw. Pull them toward you to get them away from the screw, then spreas them apart with your fingers.
3. Use (bendy shaft + #2 Phillips + bit handle) to remove the rear screw.
4. LSB, remove the front screw with (MOSS + #2 Phillips + bit handle).
5. Support the FB WYLH. Remove the rear screw WYRH.
6. Be careful with the the FB. The spark plug looking thing below the RSB FB is a PITA and gets in the way. So, lower the FB slowly and tilt it forward and away from the carb.
7. Put RSB FB and screws aside aside in a clean area. The remaining gas on the FB is a magnet for dust/crap.
III. Remove Main Jets (RSB)
1. LSB, place the 8mm wrench or adjustable crescent wrench on the Needle Jet Holder (Item A on Figure 2 of Page 3-20). We don't want to loosen this when we loosen the Main Jet, otherwise the Needle Jet (Item A on Figure 1 of Page 3-20) will drop down.
2. RSB, use (MOSS + flathead + bit handle) to the loosen the pilot jet. If we loosen the Needle Jet Holder thats ok. We just don't want to fully unthread it, cuz the Needle Jet falling out is a PITA.
3. When trying to loosen the Main Jet. Use your off index finger to hold the MOSS from the top. MOSS has a notch at the top, which is brilliant, that gives you lateral control of the bit as well as allowing some axial pressure to be applied with the finger.
3. Unthread with your fingers, don't want the Main Jet to fall.
4. Remove the 8mm wrench or adjustable crescent wrench, we do not need it for tightening.
IV. Replace Main Jets (RSB)
1. Select the Main Jet from the FP kit.
2. RSB, carefully thread, WYLH, the Main Jet. All this stuff is brass; we don't want to bitch it up. So if it starts to bite, back it out and feel for the thread.
3. Finish by tightening the jet with (MOSS + flathead + bit handle). Finger tight should suffice, again its soft brass.
V. Re-install Float Bowls (RSB)
1. Make sure the FB is free of dirt/crap (I know you left it on the floor).
2. Prep (MOSS + #2 Phillips + bit handle) with one of the FB screws.
3. LSB, WYLH move the FB in front of that spark plug thingy.
4. Pivot the FB off the spark plug thingy, and raise it to the carb.
5. Make sure the FB is fully seated. The FB and carb are well indexed to each other, there shouldn't be any free play.
6. Slowly thread the rear screw WYRH. Don't fully engage or tighten.
7. Thread the front screw. Take up most of the slack. Don't tighten fully.
8. RSB, tread and tighten the front screw. Use a firm finger torque on the bit handle.
9. Use (bendy shaft + #2 Phillips + bit handle) to thread and tighten the rear screw. You probably have to move those cables out of the way again.
10. LSB, tighten the inside screws we almost completely threaded.
***Hard part is over! Lets move to the left carb. I promise its much easier.
II. Remove Floats Bowls (LSB)
1. Start with the inside screws of the LSB FB. LSB, use (MOSS + #2 Phillips + bit handle) to loosen the inside screws.
2. Remove the outside front screw.
3. Support the FB WYLH. Remove the outside rear screw WYRH.
4. Put RSB FB and screws aside aside in a clean area.
III. Remove Main Jets (LSB)
1. RSB, place the 8mm wrench or adjustable crescent wrench on the Needle Jet Holder.
2. LSB, use (MOSS + flathead + bit handle) to the loosen the Main Jet.
3. Unthread with your fingers, don't want the Main Jet to fall.
4. Remove the 8mm wrench or adjustable crescent wrench.
IV. Replace Main Jets (LSB)
1. Select the Main Jet from the FP kit.
2. LSB, carefully thread, WYRH, the Main Jet.
3. Finish by tightening the jet with (MOSS + flathead + bit handle).
V. Re-install Float Bowls (LSB)
1. Make sure the FB is free of dirt/crap.
2. Prep (MOSS + #2 Phillips + bit handle) with one of the FB screws.
3. LSB, WYLH raise the FB to the carb.
5. Make sure the FB is fully seated.
6. Slowly thread the outside rear screw WYRH. Don't fully engage or tighten.
7. Thread the outiside front screw. Take up most of the slack. Don't tighten fully.
8. Tread and tighten the inside screws
9. Tighten the outside screws we almost completely threaded.
***Told you it was eaiser! We're not done yet though.
VI. Prime Carbs
1. Turn the fuel petcock (Item A on Figure 1 of Page 3-26) to PRI. This will allow fuel to flow to the carbs without a vacuum present.
2. Open the gas tank to make sure the air pocket in the tank doesn't prevent the fuel from flowing.
VII. Test
1. Check your brain and make sure everything is connected and tight.
2. Check the FB is not leaking.
3. Fire it up.
4. Adjust the idle (remember we moved it to the right side of the bike) intially, just to the bike can run. You'll need to adjust it once the bike is warm.
DONE!
I hope this guide will help you in your forray into jetting. I was able to reduce my jet change down to 45 min!... on my second try! That means you can devote a solid sunday afternoon to finding the best Main Jet.
I will post my jet findings on this thread as I go.
). 
