Jetting Database - Discussion Thread

[icbm]

Originally Posted by choneofakind

haha yeah. College kid here. I know what it feels like to be spending money on a bike and thinking, "huh, that's 8 more hours I need to work over break"

Yea I remember those days........20+ years ago....

[Slono]

YEAR:2011
INTAKE MODIFICATIONS: Stock
EXHAUST MODIFICATIONS: Area P 18" Quiet Core (carbon)
JET KIT OR STOCK? Jet Kit
BRAND OF JET KIT? Dynojet
MAIN JET: keihin #98
NEEDLE AND CLIP POSITION: 98 needle, clip on third notch
MIXTURE SCREW SETTINGS: 2.75 turns out
ELEVATION: 0-100

I'm having a problem diagnosing the signs my bike is giving me. I don't know the difference between bogging and stuttering. I cannot start it the first time without the choke, but if I persist one or two more times after the initial try, I can get it (without the choke). Needless to say starting up with the choke is no problem.

It doesn't pull hard, and it doesn't rev past 10,000 RPMS on the freeway however, it pulls quite evenly across the powerband.

Does this mean my bike is lean? How do I know my bike is stuttering and not bogging?

[choneofakind]

There's nothing wrong with needing choke at startup. Leave the choke on while you ride. Notice how it bogs when you take off after it's all warmed up? turn it off. no more bog.

That shows that the needs of a bike change from cold to warm. The choke is there for a reason. It wouldn't be there if it wasn't needed. Needing choke to start isn't a bad thing.

Buuuuuut, if it makes you feel better, back the mix screws out 1/8 turn, and see how the bike feels when warm. Better? keep it. worse? go back. No difference at all? you'll be fine to keep it, and start up will be a little bit easier.

only test idle mix when warm. the choke is there for starting. use it.

[Slono]

I'll give that a shot. What I don't understand is that the bike performs worse with my new exhaust and jet settings than stock. Acceleration is gradual and top speed is 15km/h less than before... rpms in 6th gear max out at 10,000.

[choneofakind]

If it's not pulling as hard at the top end, then try the next size larger jet

[Slono]

Fiddled with it again...


YEAR:2011

INTAKE MODIFICATIONS: Stock

EXHAUST MODIFICATIONS: Area P 18" Quiet Core (carbon)

JET KIT OR STOCK? Jet Kit

BRAND OF JET KIT? Dynojet

MAIN JET: #100

NEEDLE AND CLIP POSITION: Dynojet needle, clip on 3rd notch

MIXTURE SCREW SETTINGS: 3.5 turns out

ELEVATION: 0-100 ft.


So I made sure the diaphragms weren't pinched or damaged before changing the jets. I upped the jets from a size 98 dyno to a 100 dyno, and changed the idle mixture screws to 3.5 turns out from 2.75. It pulls MUCH harder all the way through the powerband. I haven't been able to test its top speed because I only have city freeways at my disposal and my license is my livelihood and I'd like to keep it

The only thing I've noticed is that when I blip the throttle it hangs a bit before returning to the 1500 rpm mark, which is what I set it to. The tachometer needle also bounces around a bit when its idling. It doesn't bounce around much, but its more than before I re-jetted it.

According to what I've found on this site, my bike is showing signs of being lean. Instead of changing to a larger jet, should I put the clip one notch lower on the needle to the 4th position?

[choneofakind]

Hey great @Slono glad it worked for you!

if it's hanging a little before returning to idle when warmed up, try backing the mix screws out 1/4 turn

EDIT: is it only showing lean signs when you blip?

also, if you're getting tach fluctuations, try syncing the carbs.

[Slono]

Originally Posted by choneofakind

Hey great @Slono glad it worked for you!

if it's hanging a little before returning to idle when warmed up, try backing the mix screws out 1/4 turn

EDIT: is it only showing lean signs when you blip?

also, if you're getting tach fluctuations, try syncing the carbs.

The screws are already backed out 3.5 turns. Backing it out another 1/4 of a turn will make it 3.75 turns out. Is that too far out?

I *think* those are the only lean signs I'm getting. There's no stuttering and for the most part the throttle seems a tad more sensitive than when it was stock.

Actually now that I think of it, when I roll on the throttle before releasing it hangs a bit before returning to 1500 rpms. But if I blip, the rpms dip before returning to the preset idle speed. I'm confused now, does this mean its rich? I haven't had any bogging problems...

[choneofakind]

ok. the idle mix is adjusted based on how it feels when you blip it after it's warmed up. If it's dipping below idle, then turn them in 1/4 turn. 3.5 turns seems a little far out for stock intake when the idle mix screws come at 2.5 turns out stock.

Give it a try both ways and see which one feels better.

[Slono]

Originally Posted by choneofakind

ok. the idle mix is adjusted based on how it feels when you blip it after it's warmed up. If it's dipping below idle, then turn them in 1/4 turn. 3.5 turns seems a little far out for stock intake when the idle mix screws come at 2.5 turns out stock.

Give it a try both ways and see which one feels better.

Ok thanks. I'll give that a shot sometime soon.

[Slono]

What's the difference between shimming your needles and increasing the jet size?

[choneofakind]

As there is more air going through your carbs, the slides move up. This increases volume and keeps the velocity of the air constant. Hence Constant Velocity carbs.

Your needles are attached to your slides. As the slides raise, the needles move up as well. As the needles move up and down, they move in and out of the main jet. At, WOT, the needles are completely out of the main jet.

If you need more gas at WOT, you can raise the needles as much as you want, but it won't do a thing. The main jets are the only thing in charge of how much fuel is delivered at WOT.

The needles are in charge of how much fuel is delivered in the mid-range of the throttle because that is where the slides are moving up and down.

Make sense?

[Slono]

Yes that makes complete sense. Thank you for that explanation! The reason why I was asking was because I was wondering if I would be able to shim my needles instead of increasing jet size since my idle seems to hang when I roll on the throttle and abruptly release. It's also still giving me conflicting readings though, I would hang, but also sag below normal idle if I blipped.

[choneofakind]

That sounds like an issues of the pilot jets, not the main jets.

have your carbs gotten dirty at all? try cleaning the idle passages really well with compressed air and and aerosal can of carb cleaner

[Slono]

Do I take the idle screws completely out before cleaning?

[choneofakind]

yeah, it's not a bad idea to remove those.

http://faq.ninja250.org/wiki/Cleaning_the_carbs_2

[Slono]

Originally Posted by choneofakind

yeah, it's not a bad idea to remove those.

http://faq.ninja250.org/wiki/Cleaning_the_carbs_2

I put 3/4 of a can of sea foam into my tank and took the bike for a 10 minute ride on the highway. When I got back to my house I found it idling at 5k rpms... The sea foam obviously did wonders since I hadn't changed anything from a couple days ago.

The throttle response is better too... I'll post a video and hopefully you can tell me if it's respOnding the way it's supposed to.

[choneofakind]

WOOT!!! I thought 3.5 turns out with lean symptoms sounded odd

have fun riding

[Slono]

Originally Posted by choneofakind

WOOT!!! I thought 3.5 turns out with lean symptoms sounded odd

have fun riding

Thanks for all your help Chris, you've probably replied to all my posts regarding my bike, haha.

Now all I need to do is turn the idle mixtures back to stock and readjust from there. Are the dynojet and factory pro jets better than the stock by a lot or is the difference negligible? If I pull my air box I'll have to order another dynojet kit and that would cost me much more than if I ordered individual jets from jets r us.

[choneofakind]

No worries. I can't ride except in the summer since I'm at school, so I might as well bum around on ninjette

The difference is negligible. If you're going to pull the airbox and replace it with a pod filter, get a pair of 108, 110, and 112 main jets. You'll likely want to get the next size up on pilot jet as well, but I'm not sure what size jet that is for a newgen.

There's a link to the right kind of jet from jetsrus on the first post in this thread I believe.

If you're going to delete the airbox and rejet, you should replace the screws on the bowls and caps of your carbs as well. The more jetting changes you make, inevitably you're going to strip some. They take m4x16 screws. I replaced all 16 on mine with stainless m4x16 hex head screws.

[expat]

I have an 08 250 which is stock apart from a Hotbodies slip on. (No DB killer)
It runs like a pig until you clean it out above around 5K RPM.
I know these things are clod blooded but this is ridiculous!
Took the carbs off, cleaned them, added some sea foam to the gas all to no avail.
I had a similar issue with a DRZ125 I had some time ago and went up on the pilot jet.
Anyone have any suggested base line carb settings (main jet, pilot jet and air screw) for me to use as a base line?
Thanks!!

[choneofakind]

@expat, raise the needles by adding washers in 1 washer increments. That should richen your mid-range back up. With just a slip-on, you should be fine on the stock 98 main jets.

start with one washer.
test ride.
add a 2nd washer.
test ride.
add a third washer.
test ride.
add a 4th washer.
test ride.

go back to/stick with the number of washers that felt best and was the smoothest throughout the entire mid-range.

[expat]

Thanks!
I can try that but it feels more pilot circuit starvation...
Will start with 2 washers tomorrow but anyone with a baseline other than washers, please post up!

[expat]

3 washers... running like a charm!!
Cheers for the advice!

[choneofakind]

You're welcome. Glad to help

[abhijitz]

Can someone tell me what Factory Pro # does Dynojet # correspond to. A rough idea would help. (The size comparison is only available for Keihin, Mikuni, Dynojet)

[zzrguy]

Just thought I should inform everyone I found a really cheap place to buy screws for the float bowls! In us and canada! I was looking all over so I figured id save you guys some time.
http://www.fastenal.com/web/products...S2530014A20000
Sure beats OEM Price at my dealer... They want 4 bucks a screw.. 20 cents seems way better for a hex head

[cuong-nutz]

Originally Posted by abhijitz

Can someone tell me what Factory Pro # does Dynojet # correspond to. A rough idea would help. (The size comparison is only available for Keihin, Mikuni, Dynojet)

The Factory Pro Jet number sizes are the same as the Keihin's. Example: a 110 Keihin jet is the same as 110 Factory Pro and vice versa.

THe DynoJet numbering varies slightly as you can see from the chart below.

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

[kavo]

Does anyone know what the sportisi jet kit numbers correspond to?

[Steven250R]

Originally Posted by cuong-nutz

The Factory Pro Jet number sizes are the same as the Keihin's. Example: a 110 Keihin jet is the same as 110 Factory Pro and vice versa.

Are you 100% sure of this?

[cuong-nutz]

Yep. If you don't believe me you can call factory pro to confirm.

[rdano1197]

YEAR: 2008

INTAKE MODIFICATIONS: air box removed. K&N R-0990 Filter

EXHAUST MODIFICATIONS:Jardine RT-5 full system, Kleen air system removed

JET KIT OR STOCK? Jet Kit

BRAND OF JET KIT? Factory Pro Stage 2

MAIN JET: 115

NEEDLE AND CLIP POSITION: 4 (no shims)

MIXTURE SCREW SETTINGS: 2-1/2 turns out from bottom, initially

ELEVATION: 177 ft

MISCELLANEOUS INFORMATION ABOUT YOUR BIKE’S JETTING SETUP:
Seems to be running good. In low gear pulls hard from the start all the way to redline. Higher gears it pulls real well from 6k to redline (at appropriate speeds vs gear). At start when cold needs a little choke to stay running, 2 minutes later no choke needed. Once I get the money I will take it to get dyno'd.

[x only performance]

YEAR: 2008 Ninja 250r

INTAKE MODIFICATIONS: K&N P/N "R-0990"

EXHAUST MODIFICATIONS: MGP Growler Slip-on

JET KIT OR STOCK? Stock I think

BRAND OF JET KIT? Unknown

MAIN JET: Stock I think

NEEDLE AND CLIP POSITION: Stock I think

MIXTURE SCREW SETTINGS: Stock I think

ELEVATION: Around 700 ft

MISCELLANEOUS INFORMATION ABOUT YOUR BIKE’S JETTING SETUP:

[dino74]

Not to be a jerk but this post is pretty useless...

If you're using the KN pods you really really should rejet the carb. You might be running lean which could harm your engine in the long run.

Originally Posted by x only performance

YEAR: 2008 Ninja 250r

INTAKE MODIFICATIONS: K&N P/N "R-0990"

EXHAUST MODIFICATIONS: MGP Growler Slip-on

JET KIT OR STOCK? Stock I think

BRAND OF JET KIT? Unknown

MAIN JET: Stock I think

NEEDLE AND CLIP POSITION: Stock I think

MIXTURE SCREW SETTINGS: Stock I think

ELEVATION: Around 700 ft

MISCELLANEOUS INFORMATION ABOUT YOUR BIKE’S JETTING SETUP:

[cuong-nutz]

I totally agree. If he was able to install the pods, he could have just cracked opened the carbs and took a look to see what was inside. Lol. He was just right there already!

[FishaRneked]

^ I think that bike must have been jetted (probably bought the bike already setup) I tried to ride mine for the heck of it with the K&N990 but not jetted yet...Didnt get anywhere, wouldnt rev at all.

[sharky nrk]

Trying to put my bike back together after an off at the track and pulled the airbox during the tear down and a full exhaust is going on as well. I was debating on a jet kit or just buying individual jets. Any reason I can't just buy a set of 110s or 112s and 40 pilots to start with and use the stock needles? I have access to free stainless allen/hex screws so no benefit there.

[NJ Ninjette]

Originally Posted by sharky nrk

Trying to put my bike back together after an off at the track and pulled the airbox during the tear down and a full exhaust is going on as well. I was debating on a jet kit or just buying individual jets. Any reason I can't just buy a set of 110s or 112s and 40 pilots to start with and use the stock needles? I have access to free stainless allen/hex screws so no benefit there.

I've recently ordered a full exhaust and this is my plan, we do it all the time in the dirt bike world. But we also have access to a larger knowledge base and usually a proven assortment of needles to work with too.

A jet kit should give a much better baseline to start with, make the process easier, and generally give better results. But, the DIY approach should be close enough for my street use.

[Countersteer]

Here is my setup:

YEAR: 2008

INTAKE MODIFICATIONS: air box removed. K&N R-0990 Filter

EXHAUST MODIFICATIONS: DanMoto GP Titanium slip-on, Catalytic converter removed from header, header shortened 4 inches, Clean air system removed

JET KIT OR STOCK? Jet Kit

BRAND OF JET KIT? 6 Sigma Racing

MAIN JET: 117.5

PILOT JET: 40

VACUUM SLIDE: Additional hole with #59 drill bit

VACUUM SLIDE SPRING: 1 loop cut off (1/8 inch)

NEEDLE AND CLIP POSITION: 2 Shims per needle

MIXTURE SCREW SETTINGS: 2-1/2 turns out from bottom

ELEVATION: 0 to 500 feet

MISCELLANEOUS INFORMATION ABOUT YOUR BIKE’S JETTING SETUP:
Bike seems to start and idle good, choke for a couple minutes, but then once warm and off choke it seems to have a very slight stumble or hesitation.


So I'm trying to figure out my first move toward dealing with the lean issue. I will say that after the bike is fully warm and I'm at a steady RPM, say 8k or 9k, and bring the choke on 1/2 to 3/4 the stumble/hesitation goes away.

Thanks for any help!

[PsHYk]

so should i do DynoJet or Factory Pro ?
the dyno jet kit i saw according to the reviews has a 100 main jet do you guys know
which ones it comes with and if the 2011 and 2011 ones would be the same or different?