After Jetting, bike runs odd

[drunyon]

Im not sure if it was just because it was super cold out but I finished jetting the bike last night, put it all together (surprised we got it right the first time), then let it warm up. I took it out for a ride and it seemed to stumble a lot midrange and high range it rode like a beast! Could the cold have been causing the midrange to suck or do i need to drop down to a different jet level?

I have the dyno jet kit and I installed the 100's in it.

I just did the air pods conversion and I have a danmoto slip on exhaust. Also the side fairings were off.

Any help is appreciated, if the jets need changed, im just going to take it to a shop this time. I would assume since I had both high flow mods that I would need the higher jet. Also this bike was untouched by the prev. owner yet the jet inside the carb said 98 on it. It was stock jets because he was the only owner.

not sure if the throttle cable could need adjusting or if its the jets or the cold out, planned on trying when it was a little warmer.


Thanks !

[Motofool]

Rising the needles some maybe?

Welcome to the site !!!

[drunyon]

It was in the high 30s out, and I dont think a carb'd bike likes that cold weather. Esp since im running on a pod filter with no fairings lol.
I'm hoping it was just a temperature issue/low fuel. Going to get some good stabil stuff from walmart later and fill up the tank, I noticed one of the main jets when removing it seemed a little dirty.
My friend and I agreed we will not be taking this thing apart again lol, getting that pod filter onto the carb was a PITA!

[DaBlue1]

Originally Posted by drunyon

....I have the dyno jet kit and I installed the 100's in it.

....I just did the air pods conversion and I have a danmoto slip on exhaust.

100 mains are too small for pods. You need to go bigger on the mains or put the airbox back in with snorkel removed.

Here's some useful info;
There are many factors that will change the performance of the engine. Altitude, air temperature, and humidity are big factors that will affect how an engine will run. Air density increases as air gets colder. This means that there are more oxygen molecules in the same space when the air is cold. When the temperature drops, the engine will run leaner and more fuel will have to be added to compensate. When the air temperature gets warmer, the engine will run richer and less fuel will be needed. An engine that is jetted at warmer temps may run poorly when the temperature is colder and vice versus, so proper jetting is essential.

The bike will actually run better up top with a little extra oxygen. However you do want to be careful at freezing temps.The Ninja 250 is susceptible to carb icing in certain conditions. For the Ninja 250, it appears that the range of about 20° F to 50° F (-7° C to +10° C) with visible moisture (fog or rain) can cause carb ice. Pod air filters may exacerbate the problem, since they can allow more moisture into the carbs than the stock airbox.

[drunyon]

Originally Posted by DaBlue1

100 mains are too small for pods. You need to go bigger on the mains or put the airbox back in with snorkel removed.

Here's some useful info;
There are many factors that will change the performance of the engine. Altitude, air temperature, and humidity are big factors that will affect how an engine will run. Air density increases as air gets colder. This means that there are more oxygen molecules in the same space when the air is cold. When the temperature drops, the engine will run leaner and more fuel will have to be added to compensate. When the air temperature gets warmer, the engine will run richer and less fuel will be needed. An engine that is jetted at warmer temps may run poorly when the temperature is colder and vice versus, so proper jetting is essential.

The bike will actually run better up top with a little extra oxygen. However you do want to be careful at freezing temps.The Ninja 250 is susceptible to carb icing in certain conditions. For the Ninja 250, it appears that the range of about 20° F to 50° F (-7° C to +10° C) with visible moisture (fog or rain) can cause carb ice. Pod air filters may exacerbate the problem, since they can allow more moisture into the carbs than the stock airbox.

That helps out quite a bit thank you. Well the dyno jet kit came with 100s at the highest, what size will I need to get? My friend ordered his jets from jetsrus.com individually. I know I will NOT be doing the rejetting myself again. Putting the airbox back in is not an option . We ended up using a pcv valve for the ventillation on top of the tranny using the original hose that was connected to the airbox. It was in the high 30s plus i had the plastics off so I have a good feeling that was most of the issue.

This is the site for the jets: http://jetsrus.com/a_jet_kit_street/...50R_Ninja.html

[subxero]

Originally Posted by drunyon

It was in the high 30s out, and I dont think a carb'd bike likes that cold weather. Esp since im running on a pod filter with no fairings lol.
I'm hoping it was just a temperature issue/low fuel. Going to get some good stabil stuff from walmart later and fill up the tank, I noticed one of the main jets when removing it seemed a little dirty.
My friend and I agreed we will not be taking this thing apart again lol, getting that pod filter onto the carb was a PITA!

Carbs need tuned for the weather if you want it to run optimal during each season.

From 1/2 to Wide Open Throttle (WOT) is your main jet, so sounds like you probably got that correct from your description of it running like a beast up high.

Needle and needle jet control most of 1/4-3/4 throttle. Sounds like you need to adjust the needle. Can't tell you which way you need to go, up or down with out seeing the bike run, IF it is rich it will bog, if it is lean it will still run off but it is different than a bog, hard to describe.

if your troubles are from idle - 1/4 throttle your pilot and air screw most likely


good luck

[drunyon]

Originally Posted by subxero

Carbs need tuned for the weather if you want it to run optimal during each season.

From 1/2 to Wide Open Throttle (WOT) is your main jet, so sounds like you probably got that correct from your description of it running like a beast up high.

Needle and needle jet control most of 1/4-3/4 throttle. Sounds like you need to adjust the needle. Can't tell you which way you need to go, up or down with out seeing the bike run, IF it is rich it will bog, if it is lean it will still run off but it is different than a bog, hard to describe.

if your troubles are from idle - 1/4 throttle your pilot and air screw most likely


good luck

Yeah it seems like 3/4-WOT works really well. If it's the pilots or needles I'll probably let the shop just deal with it. I'll have them install my sprocket as well. Like when I do like 1/2-3/4 throttle it bogs for a second then zips away. Almost did a freakin wheelie in first.

[Motofool]

Originally Posted by subxero

......Can't tell you which way you need to go, up or down with out seeing the bike run, IF it is rich it will bog, if it is lean it will still run off but it is different than a bog, hard to describe..........

When in doubt, try the richer mix first (rise needles up).

[subxero]

Originally Posted by Motofool

When in doubt, try the richer mix first (rise needles up).

^this would be wise, a little rich won't cause serious issues in the short term when figuring out jetting, a little lean on the other hand...

[subxero]

Originally Posted by drunyon

Yeah it seems like 3/4-WOT works really well. If it's the pilots or needles I'll probably let the shop just deal with it. I'll have them install my sprocket as well. Like when I do like 1/2-3/4 throttle it bogs for a second then zips away. Almost did a freakin wheelie in first.

check out the DIY, i think there is a thread in there about changing jets with out removing carbs. I could be wrong i but i thought i remembered reading it somewhere. If not Search function is your friend. So that might be an option instead of getting ripped off by a cycle shop

[drunyon]

Originally Posted by subxero

check out the DIY, i think there is a thread in there about changing jets with out removing carbs. I could be wrong i but i thought i remembered reading it somewhere. If not Search function is your friend. So that might be an option instead of getting ripped off by a cycle shop

I've tried that method, the right angle was a PITA to use. since i stripped out a few i replaced it with allen screws. I'll prob have a shop do it next time.

[drunyon]

is it possible I need to use higher than 87 octane now??

[Jiggles]

Originally Posted by drunyon

is it possible I need to use higher than 87 octane now??

No


100 mains are too small, what clip position did you set the needles too?

[drunyon]

All my friend and I did was replace the mains and put back together. What size should I order from jetsrus.com when I take it to the shop?? 100 was the largest in the dynojet kit

[Jiggles]

Well jetsrus is Keihn which are different sizes. I'd say order everything from a 104 to a 112. Btw the shop is going to charge you an exorbitant amount of money to do the jetting. Just do it yourself, it's not very hard

And you need to put in the dynojet needles, it's easier than the main jets

[subxero]

Originally Posted by drunyon

is it possible I need to use higher than 87 octane now??

octane rating has to do with compression, 250 runs safe and great on 87 keep it that way.

[drunyon]

I told myself I'm not taking the damn thing back apart myself lol. It's gotta go to the shop in the spring anyways so figured why not. I just took it out, put stabil in it and filled the tank. The warmer air seems to made it run a lot better as well as warming it up, it still seems to stumble a little bit in the midrange though.

[Jiggles]

C'mon man! All you gotta do is take the gas tank off, its not like it's a valve adjustment. Besides if you let the shop jet it they will either just guess and leave it running ok or charge you alot more and do it right

[drunyon]

Originally Posted by Jiggles

C'mon man! All you gotta do is take the gas tank off, its not like it's a valve adjustment. Besides if you let the shop jet it they will either just guess and leave it running ok or charge you alot more and do it right

I know the shop would do it the right way and make sure it's running right, its a local shop I know of. It was a lot more work than I anticipated. I wasnt sure if it was going to be running anymore lol. I have to take it in for the sprocket anyways. And for my clutch/brake handles.

[subxero]

Originally Posted by Jiggles

C'mon man! All you gotta do is take the gas tank off, its not like it's a valve adjustment. Besides if you let the shop jet it they will either just guess and leave it running ok or charge you alot more and do it right

^this

They will most likely not take the time to do it correctly and just set everything up so it runs ok.

[Motofool]

Originally Posted by drunyon

....The warmer air seems to made it run a lot better as well as warming it up, it still seems to stumble a little bit in the midrange though.

Jiggles is correct, the mix is lean at WOT.

It is even leaner in the midrange.

Restricting the flow of air going through the filters would help harmonize the air intake with the current fuel supplied by the jets.

[Jiggles]

Originally Posted by subxero

^this

They will most likely not take the time to do it correctly and just set everything up so it runs ok.

And by doing it right I mean they will charge you $200+

[drunyon]

Well I know they wont charge me just $1 lol. I need them to do the sprocket and controls anyways so figured I'll just have em do the jetting at the same time. I trust this shop, a few local people on stlryderz.com trust them as well. I think maybe having the fairings back on would help a little, because I have the pods and there was nothing covering them when I ran it yesterday. Figured the fairings would somewhat act as a box.

I sure hope I don't need higher jets, the dynojet kit seems like I wasted my $$ now. I'll probably throw the rest of the kit for sale on here cheap.

[Rudiger]

Originally Posted by DaBlue1

When the temperature drops, the engine will run leaner and more fuel will have to be added to compensate. When the air temperature gets warmer, the engine will run richer and less fuel will be needed. An engine that is jetted at warmer temps may run poorly when the temperature is colder and vice versus, so proper jetting is essential.

I have been thinking about yanking out my airbox and getting headers. So with what you said above, does this mean I would have to change the jetting from the summer to fall every year to have it run well? I don't want do this if i have to change the jetting every season.

[DaBlue1]

Originally Posted by drunyon

.... I think maybe having the fairings back on would help a little, because I have the pods and there was nothing covering them when I ran it yesterday. Figured the fairings would somewhat act as a box.

....I sure hope I don't need higher jets, the dynojet kit seems like I wasted my $$ now. I'll probably throw the rest of the kit for sale on here cheap.

Your fairings have no affect on the air flow of pod filters. The dyno kit you got was made for a bike with the stock airbox, snorkel removed and slip ons, not pod air filters. The instructions say remove the snorkel, not the whole airbox. That's why your jets are too small.

[drunyon]

I think if it's jetted right it wont need to be rejetted every season. If you can live with a few inconsistincies.

Yeah I just need to find out which jets I need to get now, The stock one said 98 on the side of it but the one's i put in were 100. I dont mind running a little rich. I am never putting the airbox back in, i dont feel like buying a new one

[DaBlue1]

Originally Posted by Rudiger

I have been thinking about yanking out my airbox and getting headers. So with what you said above, does this mean I would have to change the jetting from the summer to fall every year to have it run well? I don't want do this if i have to change the jetting every season.

You don't have to change jets every season. What you do is find the happy medium where the settings works well for both winter and summer. Keep in mind that a 3% slight rich mixture is better than a 3% lean mixture.

BTW it has been proven that you don't have to remove the airbox and add a full exhaust system to get very close to max gains. a bike with a full system, 98 mains and stock airbox w/snorkel in can get similar results as a bike with pod filters, large mains and a full system. http://www.ninjette.org/forums/showt...light=dyno+run

Sound and performance(HP) is what everyone wants anyway right?

[DaBlue1]

Originally Posted by drunyon

I think if it's jetted right it wont need to be rejetted every season. If you can live with a few inconsistincies.

Yeah I just need to find out which jets I need to get now, The stock one said 98 on the side of it but the one's i put in were 100. I dont mind running a little rich. I am never putting the airbox back in, i dont feel like buying a new one

With the stock header and slip on, start with 105's or 108 mains. 110's or bigger are good if you had a full system.

[drunyon]

Any idea what jet from jetsrus.com i should be looking at getting? It seems like the only issue its having is the midrangeish. When its 7000+ it's fine, usually what I run in anyways. I typically go WOT anyways :P

[subxero]

Originally Posted by Rudiger

I have been thinking about yanking out my airbox and getting headers. So with what you said above, does this mean I would have to change the jetting from the summer to fall every year to have it run well? I don't want do this if i have to change the jetting every season.

Yeah sorry for the confusion, when i said that "if you want your bike to run optimal you will adjust jetting seasonally" i just meant that jetting is affected by the weather so you should notice changes between temps, most people don't change jetting every season just cuz PITA. but then again, MX dirtriders jet every race!

But in a perfect world i would jet for seasonal temps but i'm lazy. Like others have said, you find a happy median. If you jet your bike to run optimal in cooler atmospheric temps it will run slightly rich at higher atmospheric temps which is safe as opposed to having it run lean in cooler temps.

good luck keep us posted.

[subxero]

Originally Posted by drunyon

Any idea what jet from jetsrus.com i should be looking at getting? It seems like the only issue its having is the midrangeish. When its 7000+ it's fine, usually what I run in anyways. I typically go WOT anyways :P

check out the jetting data base and look for a similar setup to your bike and someone who lives in a similar climate and elevation.

Use that as a baseline, and order a few higher, and a few lower and go to town. Try them till you find the one that lets your bike run the best and again if you are unsure between 2 jets similar in size, go with the richer setting just for ease of mind

[drunyon]

Originally Posted by subxero

check out the jetting data base and look for a similar setup to your bike and someone who lives in a similar climate and elevation.

Use that as a baseline, and order a few higher, and a few lower and go to town. Try them till you find the one that lets your bike run the best and again if you are unsure between 2 jets similar in size, go with the richer setting just for ease of mind

So the dynojet sizes are the same as the genuine keihn ones correct? I'm running a 100 right now and I feel maybe a few sizes higher would work great. So I'm looking at 102/104?

http://faq.ninja250.org/wiki/Dynojet...zes_conversion

according to this im running lower than stock?? the jet we took out showed it said 98..

[drunyon]

YEAR: 2008

INTAKE MODIFICATIONS: K&N R-0990

EXHAUST MODIFICATIONS: Yoshi USA SS S/O

JET KIT OR STOCK? Jet

BRAND OF JET KIT? Factory Pro 3.0

MAIN JET: 112

NEEDLE AND CLIP POSITION: 2 with two washers under clip

MIXTURE SCREW SETTINGS: 2 1/2

ELEVATION: 100

MISCELLANEOUS INFORMATION ABOUT YOUR BIKE’S JETTING SETUP: In Progress still need to sync, What a PITA it is to make theese changes. The Bike is louder and twice as responsive without any dead spots. Before the install of all of the above, it was like riding a moped. Now its a Ninja!

THIS is most likely what my setup is. I'll probably get the jets and have the shop do it. I'll give them the info on what this says. I seen a lot of people say 112 main, assuming thats the genuine keihn?

[subxero]

^ looks like a good reference. Unfortunately jetting is trial and error. Good luck

[drunyon]

Originally Posted by subxero

^ looks like a good reference. Unfortunately jetting is trial and error. Good luck

I've seen a lot of people use the 112. Since I got rid of the airbox, should be much easier for the shop to do the jetting.

[menikmati]

Originally Posted by drunyon

THIS is most likely what my setup is. I'll probably get the jets and have the shop do it. I'll give them the info on what this says. I seen a lot of people say 112 main, assuming thats the genuine keihn?

FP uses the same jet numbering/sizing so yes.

Since you've already changed your main jets then I would say that experimenting with the needle height should be easy in comparison. Just remove the gas tank for access to the carb tops.

Invest in a MOS if you want to do your jetting with the carbs still on the bike.

[drunyon]

Originally Posted by menikmati

FP uses the same jet numbering/sizing so yes.

Since you've already changed your main jets then I would say that experimenting with the needle height should be easy in comparison. Just remove the gas tank for access to the carb tops.

Invest in a MOS if you want to do your jetting with the carbs still on the bike.

I got the MOS but it was a PITA to use! So im returning it. I've only got a 100 jet in the bike, gotta purchase the 112's and have the shop do the needle/screw adjustment.

[subxero]

Originally Posted by drunyon

I got the MOS but it was a PITA to use! So im returning it. I've only got a 100 jet in the bike, gotta purchase the 112's and have the shop do the needle/screw adjustment.

wish you lived by me, i would jet your bike for half the price of the dealer i could use a few hundred bucks!!

[drunyon]

Originally Posted by subxero

wish you lived by me, i would jet your bike for half the price of the dealer i could use a few hundred bucks!!

yeah that would be awesome lol.

[drunyon]

Got the 2 112 jets ordered. Can't believe how much they rape you on shipping though. I may attempt to put them in myself, seeing how I replaced the pos screws for allen heads when I had the carb out. I just hope I can reach all of the bolts.