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kkim · December 3rd, 2008, 11:23 AM

EDIT: This thread is for jetting specs only; jetting discussion can continue in this discussion thread.

The purpose of this thread is to consolidate the information from people who have done any type of work to their carburetor jetting to improve the stock bike's rideability. Your contributions are what will make this a valuable tool for anyone looking to rejet their bike in the future.

Are you nuts!!??? Why would anyone want to even consider rejetting their perfectly good, brand new bike?

The stock 250R is marketed as a high mileage, economy bike and as such, the factory has seen to jet the bike as lean as possible to eek out the very best MPG numbers and to also adhere to emissions laws in the US. Kawasaki has done a very good job in selecting the best combination of jetting components to make the 250R a very miserly, gas sipping vehicle. It is ironic, however, that the very jetting which makes the bike a gas sipper, makes it a very unfriendly beginner bike as far as throttle control and rideability. Add to that, poor quality control at setting the mixture screws properly from the factory and you end up with a bike that is difficult to start, takes a long time to warm up and even when warm is difficult to get moving from a stop without revving it to about 4-5k just to get moving smoothly. Add to that the sometimes unexpected hiccup when the bike is just starting to get moving and you end up with a lot of dropped bikes from beginners. Instead of being rider friendly, it makes riding the bike lot more difficult than it needs to be. Rejetting your bike will address this low speed glitch. If you would like more info on jetting, this is a very good primer… http://faq.ninja250.org/wiki/I_want_...uretor_jetting

Any other benefits?

Glad you asked!! With rejetting, it is possible to extract more power out of the little 250 motor. The factory tuned it for mileage… you can tinker with the jetting to extract more power, though be advised gas mileage will be affected. What I like is that rejetting increases the amount of power available in the lower rpms ranges and in doing so makes the bike much easier to ride and much more rider friendly… two things that greatly benefit someone new to riding a motorcycle.

So, on to the purpose of this thread... In brief, please cut and paste the following as I have in post #2 and help start building a database in the 250R forum. As much as possible, please stay on topic (yeah, right!!) so the information will be easily accessible by those searching for jetting help in the future. You are more than welcome to come back and post new jetting specs in the future in another post if you should redo your jetting. Please comment on any improvements rejetting did for you if you do repost.

As a baseline, these are the stock 2008 jetting specs-

From the service manual-

Make, Type- Keihin, CVK30

Main Jet- #98

Optional mains- #92,95,100,102

Main Air Jet- #100

Jet Needle- left-N9VU right-N9VW

Needle Jet- #6

Pilot Jet- #38

Pilot Air Jet- #100

Starter Jet- #48

Pilot Screws (turns out)- left- (2 1/2) right- (1 3/4)

Throttle Valve- 11degrees 00seconds

Idle Speed- 1300 +/- 50 rpm

Carb Sync Vacuum- less than 2.7 kPa (2 cmHg) difference between two carburetors.

Service Fuel Level- 0.5 +/-1mm (0.02 +/-0.04 in.) above the mating surface of the carburetor float bowl.

Float Height- 17 +/-2mm (0.67 +/-0.08 in.)

---------------------------------------------------------------------------------------

Here are some main jet conversions between manufactures-

Width------Keihin # -- DynoJet # --- Mikuni #
0.0350---- 92.5--------- 92----------- 86.3
0.0360---- 95----------- 94----------- 88.1
0.0370---- 97.5--------- 96----------- 90.0
0.0380---- 100---------- 98----------- 91.9
0.0390---- 102.5------- 100---------- 93.8
0.0400---- 105--------- 102---------- 95.6
0.0410---- 107.5------- 104---------- 97.5
0.0420---- 110--------- 106---------- 99.4
0.0430---- 112.5------- 108--------- 101.3
0.0440---- 115--------- 110--------- 103.1
0.0450---- 117.5------- 112--------- 105.0
0.0460---- 120--------- 114--------- 106.9
0.0470---- 122.5------- 116--------- 108.8
0.0480---- 125--------- 118--------- 110.6
0.0490---- 127.5------- 120--------- 112.5
0.0500---- 130--------- 122--------- 114.4

Mahalo to all that contribute.

-----------------------------------------------------------------------------------------------------------------

YEAR:

INTAKE MODIFICATIONS:

EXHAUST MODIFICATIONS:

JET KIT OR STOCK?

BRAND OF JET KIT?

MAIN JET:

NEEDLE AND CLIP POSITION:

MIXTURE SCREW SETTINGS:

ELEVATION:

MISCELLANEOUS INFORMATION ABOUT YOUR BIKE’S JETTING SETUP:

.

December 3rd, 2008, 11:23 AM	#1
kkim Join Date: Nov 2008 Posts: Too much.	Jetting Database EDIT: This thread is for jetting specs only; jetting discussion can continue in this discussion thread. The purpose of this thread is to consolidate the information from people who have done any type of work to their carburetor jetting to improve the stock bike's rideability. Your contributions are what will make this a valuable tool for anyone looking to rejet their bike in the future. Are you nuts!!??? Why would anyone want to even consider rejetting their perfectly good, brand new bike? The stock 250R is marketed as a high mileage, economy bike and as such, the factory has seen to jet the bike as lean as possible to eek out the very best MPG numbers and to also adhere to emissions laws in the US. Kawasaki has done a very good job in selecting the best combination of jetting components to make the 250R a very miserly, gas sipping vehicle. It is ironic, however, that the very jetting which makes the bike a gas sipper, makes it a very unfriendly beginner bike as far as throttle control and rideability. Add to that, poor quality control at setting the mixture screws properly from the factory and you end up with a bike that is difficult to start, takes a long time to warm up and even when warm is difficult to get moving from a stop without revving it to about 4-5k just to get moving smoothly. Add to that the sometimes unexpected hiccup when the bike is just starting to get moving and you end up with a lot of dropped bikes from beginners. Instead of being rider friendly, it makes riding the bike lot more difficult than it needs to be. Rejetting your bike will address this low speed glitch. If you would like more info on jetting, this is a very good primer… http://faq.ninja250.org/wiki/I_want_...uretor_jetting Any other benefits? Glad you asked!! With rejetting, it is possible to extract more power out of the little 250 motor. The factory tuned it for mileage… you can tinker with the jetting to extract more power, though be advised gas mileage will be affected. What I like is that rejetting increases the amount of power available in the lower rpms ranges and in doing so makes the bike much easier to ride and much more rider friendly… two things that greatly benefit someone new to riding a motorcycle. So, on to the purpose of this thread... In brief, please cut and paste the following as I have in post #2 and help start building a database in the 250R forum. As much as possible, please stay on topic (yeah, right!!) so the information will be easily accessible by those searching for jetting help in the future. You are more than welcome to come back and post new jetting specs in the future in another post if you should redo your jetting. Please comment on any improvements rejetting did for you if you do repost. As a baseline, these are the stock 2008 jetting specs- *From the service manual-* *Make, Type- Keihin, CVK30* *Main Jet- #98* *Optional mains- #92,95,100,102* *Main Air Jet- #100* *Jet Needle- left-N9VU right-N9VW* *Needle Jet- #6* *Pilot Jet- #38* *Pilot Air Jet- #100* *Starter Jet- #48* *Pilot Screws (turns out)- left- (2 1/2) right- (1 3/4)* *Throttle Valve- 11degrees 00seconds* *Idle Speed- 1300 +/- 50 rpm* *Carb Sync Vacuum- less than 2.7 kPa (2 cmHg) difference between two carburetors.* *Service* *Fuel* *Level- 0.5 +/-1mm (0.02 +/-0.04 in.) above the mating surface of the carburetor float bowl.* *Float Height- 17 +/-2mm (0.67 +/-0.08 in.)* *---------------------------------------------------------------------------------------* *Here are some main jet conversions between manufactures-* Width------Keihin # -- DynoJet # --- Mikuni # 0.0350---- 92.5--------- 92----------- 86.3 0.0360---- 95----------- 94----------- 88.1 0.0370---- 97.5--------- 96----------- 90.0 0.0380---- 100---------- 98----------- 91.9 0.0390---- 102.5------- 100---------- 93.8 0.0400---- 105--------- 102---------- 95.6 0.0410---- 107.5------- 104---------- 97.5 0.0420---- 110--------- 106---------- 99.4 0.0430---- 112.5------- 108--------- 101.3 0.0440---- 115--------- 110--------- 103.1 0.0450---- 117.5------- 112--------- 105.0 0.0460---- 120--------- 114--------- 106.9 0.0470---- 122.5------- 116--------- 108.8 0.0480---- 125--------- 118--------- 110.6 0.0490---- 127.5------- 120--------- 112.5 0.0500---- 130--------- 122--------- 114.4 Mahalo to all that contribute. ----------------------------------------------------------------------------------------------------------------- YEAR: INTAKE MODIFICATIONS: EXHAUST MODIFICATIONS: JET KIT OR STOCK? BRAND OF JET KIT? MAIN JET: NEEDLE AND CLIP POSITION: MIXTURE SCREW SETTINGS: ELEVATION: MISCELLANEOUS INFORMATION ABOUT YOUR BIKE’S JETTING SETUP: .