spluttering at 9000RPM

rahnos18 · September 9th, 2016, 03:30 AM

hey all, ill be as detailed as i can but its been a while since I've done my carbs....

I've got an 08 250r with an adjustable danmoto slip on, K&N in box and some random jet kit from eBay (somewhere in US) and NGK iridium plugs CR8EIX (new).

after not riding for about 7 months and doing carb work in that time (jetting, cleaning even though they were spotless), i hopped back on the bike and all was sweet, she was full of toque down low, good smooth power, which is what i need because its the commuter (never rev too high in the suburbs, too loud). then i took it up a famous country road where i am and as soon as i hit 8.6k to 9k it almost feels like its misfiring for about 1k RPM its not bogging badly, just little splutters here and there but there's less pull over 9k although it does get to redline if i keep it pinned. I've also tested it in different situations, hot, cold, morning, night, all besides when the engine is cold. I've ran it on 91 95 and 98 octane with no change. and yes I'm in Australia.

i found this layout (could be helpful) in the carb database but i couldn't find any info relating to me.

YEAR: 2008

INTAKE MODIFICATIONS: no snorkel K&N in stock box

EXHAUST MODIFICATIONS: adjustable danmoto carbon GP slip-on, stock headers

BRAND OF JET KIT? unknown, uses Keihin numbers

MAIN JET: 102.5

NEEDLE AND CLIP POSITION: stock needle 3 shims ea.

MIXTURE SCREW SETTINGS: 2.5 or 3 (cant remember)

ELEVATION: 0-2300

MISCELLANEOUS INFORMATION ABOUT YOUR BIKE’S JETTING SETUP: slide drilled (cant remember size of drill bit)

i was also supplied with pilots but again i cant remember the size. 48 comes to mind for some reason...

i also changed the sprockets to +1 front and back although that wouldn't make a difference.

any ideas would help a lot as I'm not heavily educated in this dept.

Motofool · September 9th, 2016, 05:25 AM

I would check each electrical connector along the ignition system.
It seems related to one frequency of vibration.

rahnos18 · September 9th, 2016, 05:41 AM

Quote:

Originally Posted by Motofool

I would check each electrical connector along the ignition system.
It seems related to one frequency of vibration.

huh, that never even crossed my mind, if something was loose or corroded wouldn't the same thing happen when i went over a bump in the road? I'll still have a check but its only in that rev range that it happens.

thanks!

jkv45 · September 9th, 2016, 08:04 AM

I think you may be too rich on the Main. I would take it down a size or 2 and see if that cures it.

Find a shop in the area that stocks Keihin OEM jets, and use those. A Keihin jet will have a "K" logo stamped before the number. Anything else is a pain.

3 shims on the needle may be too much with the stock airbox.

Make absolutely sure the gas is fresh (and there is no condensation in the tank) and use the recommended octane for best performance.

rahnos18 · September 9th, 2016, 07:08 PM

Quote:

Originally Posted by jkv45

Make absolutely sure the gas is fresh (and there is no condensation in the tank) and use the recommended octane for best performance.

ive checked the tank and all is good, ive filled it up about 15 time since it had been sitting. i might pull the fuel filter just check.

quick update, ive found my jet kit. its from 6sigma and they use keihin (same k as stock 98s i pulled out) they supplied 102.5 (installed) 105 and 107.5 so ill have to hunt around because im thinking bike shops around here wont stock them, this area is sh*t for bike supplies...

ill strip it down and go though the ignition system and go -1 on the shims tomorrow and report back

rahnos18 · September 11th, 2016, 02:36 AM

ok, so i stripped it down, pulled the carbs to make sure it was all clean inside (it was), removed a shim each carb. checked from spark plugs to coil pack, there was a slight bit of corrosion on a connector of the right coil pack, sanded it back and put the bike back together and went for a ride.

gave it a little squirt when it was still a bit cold and no problems revved right through to 10k nice and smooth, rode like a nanna until i got up to the hills so it was nice and hot and gave it a bit more 4k to 13k smooth as a babys bum! rode pretty hard for a while (not too hard, public roads and all) and it started to splutter again, but not constantly like it did before. maybe once in every 20 times i hit 9k, very twisty, lots of gear changes. i also found out my slide springs are cut, i have no idea how many rings were cut but it doesn't look like many, there's still quite a bit of pressure on the slide.

so I'm not sure what did it but something worked! maybe a mixture of the two...

are there any other ideas that don't include dropping a jet size? I'd like to keep the 102.5s if i can. but if there's nothing left i will.

Lazarus · September 13th, 2016, 05:29 AM

You could add more air to compensate for the extra fuel the 102.5 is allowing (not sure how you would do that other than drilling some holes in the airbox or getting pods). I suggest 100 mains. I know you just said you wanted to keep the 102.5's but I had the same problem with my 102.5 mains only it was in the 10-11.5k range. Switched to 100 mains and I was impressed by how much smoother the power came on after 9k till redline. My fuel economy received a slight bump too, although it was probably negated by my newly found heavy right hand...

rahnos18 · September 13th, 2016, 07:05 AM

downsizing jets is looking like my only option, I was hoping to smooth out the power without dropping a jet size. because of my long gears (mostly hwy riding), I wanted more juice there for the weekends, oh well I'll start looking in to who stocks jets, near me. if there's any ideas that haven't been mentioned, let me know please guys!

thanks for the replys!

RacinNinja · September 13th, 2016, 08:56 AM

Most likely your main jet is actually too small. With the K&N and a slip on, you need to go richer. If you're sputtering at high RPM's, this is an even greater sign.

If it were me, I'd try a 105 or a 108 and see if it's better. If the jets use Keihin numbers, the 48 pilot is too big. Stock is 38 so I'd go with a 40 or maybe 42.

rahnos18 · September 13th, 2016, 09:08 AM

oh ok, well seeing as I already have 105s I might chuck them in,and see what happens, if I do have to go down in size the bike will tell me straight away.

Quote:

Originally Posted by RacinNinja

If the jets use Keihin numbers, the 48 pilot is too big. Stock is 38 so I'd go with a 40 or maybe 42.

pilots are 40, I did a little edit thing but it didn't pop up...

Triple Jim · September 13th, 2016, 09:15 AM

You should be able to move the enricher (starter) lever when the problem is happening, and add a little extra fuel. If the problem gets worse, you're already too rich. If it gets better, you're too lean.

I know this works with plain Mikuni round slide carbs, so I assume it would work with these.

RacinNinja · September 13th, 2016, 09:15 AM

Quote:

Originally Posted by rahnos18

oh ok, well seeing as I already have 105s I might chuck them in,and see what happens, if I do have to go down in size the bike will tell me straight away.

pilots are 40, I did a little edit thing but it didn't pop up...

40 pilots are good!

You have a much better flowing air filter and a freely flowing exhaust. One jet size over stock isn't sufficient....which is what the 100 jet is. Stock is 98.

Pregens with dual exhaust came with a 105 main from the factory, if that tells you anything.

This has to deal with pregens in regards to jet sizes but....the principal of tuning remains. Notice the High RPM stuttering is cause by a lean condition. Same as you have........

http://faq.ninja250.org/wiki/How_to_...e_your_jetting

jkv45 · September 13th, 2016, 09:22 AM

Quote:

Originally Posted by RacinNinja

Most likely your main jet is actually too small. With the K&N and a slip on, you need to go richer. If you're sputtering at high RPM's, this is an even greater sign.

If it were me, I'd try a 105 or a 108 and see if it's better. If the jets use Keihin numbers, the 48 pilot is too big. Stock is 38 so I'd go with a 40 or maybe 42.

It will be interesting to see which is the right way.

Our Ninja Beater is running pods and a leaky stock exhaust with 108 Mains - which seems right on at around 1000 ft and temps in the mid 80s.

With the stock airbox and a K&N, I was thinking he is too big on the Main at 102.5.

I usually see sputtering and popping as too rich, and flat-running or bogging as too lean, but we'll see.

RacinNinja · September 13th, 2016, 09:47 AM

Since there isn't any relevant info in the jetting database thread for newgens other than pod filters, maybe after the last track day of the season Friday I'll tear my carbs down and see what the jets are. They should be looked at anyway and cleaned out/dried for the winter.

It has stock airbox, no snorkel, K&N filter and a pipe. Dyno sheet shows it dead nuts on the money. I'm betting it doesn't have 100 mains in it.

Then again, the OP is using a random Ebay carb jet kit. Who knows what the numbers actually are in relation to jet size.

rahnos18 · September 13th, 2016, 03:30 PM

Quote:

Originally Posted by RacinNinja

Pregens with dual exhaust came with a 105 main from the factory, if that tells you anything.

Ohhh! so that's where I got my 105s, I tore down my 05 zzr250 and thought they could come in handy haha!

can't multiquote on my phone... stupid phone.
@Triple Jim: You should be able to move the enricher (starter) lever when the problem is happening

ok I'll give this a go tonight, I'll warm it up to avg running temp, approx 70c, and pull the choke on a bit and see what it does, although it's not doing it as often as before so I'll have to test over 15-20 mins. might check the plugs again too, may have changed color,

@RacinNinja. kit is keilhin. confirmed with brand "K" stamped on all jets.

Triple Jim · September 13th, 2016, 03:36 PM

The enrichers aren't very effective with the throttle wide open, so you may have to pull it all the way to see much difference.

rahnos18 · September 13th, 2016, 03:40 PM

ok, I'll try it in stages and let you guys know, might give a hint as to how lean it may be.

rahnos18 · September 16th, 2016, 10:19 PM

Quote:

Originally Posted by Triple Jim

The enrichers aren't very effective with the throttle wide open, so you may have to pull it all the way to see much difference.

ok so i was able to try things out today after my oil change, no real difference...

because it is now very intermittent, its impossible to know when its going to happen next and i don't really want to ride around with my choke all the way on for (potentially) an hour.

i took the bike out last night and did a bunch of 3rd gear pulls and all was fine. so i didn't use the choke then as there was no need to, i might just have to chuck another size in there and see what happens.

do you guys think its possible to swap jets without pulling the carbs? i doubt it but thought id ask...

Lazarus · September 17th, 2016, 04:47 AM

It is possible but might be more of a pain in the behind than just pulling the carbs and swapping them.

Never tried it but you could remove the starter temporarily to give you a little more room to work with the carbs still in. Just a thought..

Triple Jim · September 17th, 2016, 06:26 AM

It's definitely hard to find an intermittent problem. The enricher lever idea is just a quick thing you do when you're actually having the misfiring. As you said, you don't want to ride around with it that way for any length of time.

LoD575 · September 17th, 2016, 03:58 PM

You can change the jets without removing the carbs if you have a right angle adapter. It is still a tight fit, and can be a pain in the ass.

rahnos18 · September 17th, 2016, 11:41 PM

Quote:

Originally Posted by Triple Jim

It's definitely hard to find an intermittent problem. The enricher lever idea is just a quick thing you do when you're actually having the misfiring. As you said, you don't want to ride around with it that way for any length of time.

yeah I've heard a few fouling plug stories, amongst others, not for me...

Quote:

Originally Posted by LoD575

You can change the jets without removing the carbs if you have a right angle adapter. It is still a tight fit, and can be a pain in the ass.

Quote:

Originally Posted by Lazarus

It is possible but might be more of a pain in the behind than just pulling the carbs and swapping them.

Never tried it but you could remove the starter temporarily to give you a little more room to work with the carbs still in. Just a thought..

ok ill take a look. i do have an angled bit but its pretty chunky...

JET SWAP IT IS!!!

September 9th, 2016, 03:30 AM	#1
rahnos18 ninjette.org member Name: Steve Location: Adelaide Join Date: Dec 2015 Motorcycle(s): 2008 NINJA 250R Posts: 14	spluttering at 9000RPM hey all, ill be as detailed as i can but its been a while since I've done my carbs.... I've got an 08 250r with an adjustable danmoto slip on, K&N in box and some random jet kit from eBay (somewhere in US) and NGK iridium plugs CR8EIX (new). after not riding for about 7 months and doing carb work in that time (jetting, cleaning even though they were spotless), i hopped back on the bike and all was sweet, she was full of toque down low, good smooth power, which is what i need because its the commuter (never rev too high in the suburbs, too loud). then i took it up a famous country road where i am and as soon as i hit 8.6k to 9k it almost feels like its misfiring for about 1k RPM its not bogging badly, just little splutters here and there but there's less pull over 9k although it does get to redline if i keep it pinned. I've also tested it in different situations, hot, cold, morning, night, all besides when the engine is cold. I've ran it on 91 95 and 98 octane with no change. and yes I'm in Australia. i found this layout (could be helpful) in the carb database but i couldn't find any info relating to me. YEAR: 2008 INTAKE MODIFICATIONS: no snorkel K&N in stock box EXHAUST MODIFICATIONS: adjustable danmoto carbon GP slip-on, stock headers BRAND OF JET KIT? unknown, uses Keihin numbers MAIN JET: 102.5 NEEDLE AND CLIP POSITION: stock needle 3 shims ea. MIXTURE SCREW SETTINGS: 2.5 or 3 (cant remember) ELEVATION: 0-2300 MISCELLANEOUS INFORMATION ABOUT YOUR BIKE’S JETTING SETUP: slide drilled (cant remember size of drill bit) i was also supplied with pilots but again i cant remember the size. 48 comes to mind for some reason... i also changed the sprockets to +1 front and back although that wouldn't make a difference. any ideas would help a lot as I'm not heavily educated in this dept. Last futzed with by rahnos18; September 9th, 2016 at 05:31 AM.

September 9th, 2016, 05:25 AM	#2
Motofool Daily Ninjette rider Name: Hernan Location: Florida Join Date: Mar 2011 Motorcycle(s): 2007 Ninja 250 Posts: A lot. MOTY - 2016, MOTM - Dec '12, Jan '14, Jan '15, May '16	I would check each electrical connector along the ignition system. It seems related to one frequency of vibration. __________________________________________________ *Motofool* *.................................Never ride faster than your guardian angel can fly* "Mankind is composed of two sorts of men — those who love and create, and those who hate and destroy. Love is the bond between men, the way to teach and the center of the world." - José Martí

September 9th, 2016, 08:04 AM	#4
jkv45 Rev Limiter Name: Jay Location: WI Join Date: Jul 2013 Motorcycle(s): '06 SV650n, '00 Derbi GPR, '64 CA77 Dream 305, '70 CL450 Scrambler, numerous dirt bikes Posts: A lot. MOTM - Jun '18, Oct '16	I think you may be too rich on the Main. I would take it down a size or 2 and see if that cures it. Find a shop in the area that stocks Keihin OEM jets, and use those. A Keihin jet will have a "K" logo stamped before the number. Anything else is a pain. 3 shims on the needle may be too much with the stock airbox. Make absolutely sure the gas is fresh (and there is no condensation in the tank) and use the recommended octane for best performance.
	1 out of 1 members found this post helpful.

September 11th, 2016, 02:36 AM	#6
rahnos18 ninjette.org member Name: Steve Location: Adelaide Join Date: Dec 2015 Motorcycle(s): 2008 NINJA 250R Posts: 14	fixed!!! sort of... nearly. ok, so i stripped it down, pulled the carbs to make sure it was all clean inside (it was), removed a shim each carb. checked from spark plugs to coil pack, there was a slight bit of corrosion on a connector of the right coil pack, sanded it back and put the bike back together and went for a ride. gave it a little squirt when it was still a bit cold and no problems revved right through to 10k nice and smooth, rode like a nanna until i got up to the hills so it was nice and hot and gave it a bit more 4k to 13k smooth as a babys bum! rode pretty hard for a while (not too hard, public roads and all) and it started to splutter again, but not constantly like it did before. maybe once in every 20 times i hit 9k, very twisty, lots of gear changes. i also found out my slide springs are cut, i have no idea how many rings were cut but it doesn't look like many, there's still quite a bit of pressure on the slide. so I'm not sure what did it but something worked! maybe a mixture of the two... are there any other ideas that don't include dropping a jet size? I'd like to keep the 102.5s if i can. but if there's nothing left i will.

September 13th, 2016, 05:29 AM	#7
Lazarus ninjette.org member Name: RJ Location: PA Join Date: Dec 2015 Motorcycle(s): 2008 Ninja 250 Posts: 210	You could add more air to compensate for the extra fuel the 102.5 is allowing (not sure how you would do that other than drilling some holes in the airbox or getting pods). I suggest 100 mains. I know you just said you wanted to keep the 102.5's but I had the same problem with my 102.5 mains only it was in the 10-11.5k range. Switched to 100 mains and I was impressed by how much smoother the power came on after 9k till redline. My fuel economy received a slight bump too, although it was probably negated by my newly found heavy right hand...
	1 out of 1 members found this post helpful.

September 13th, 2016, 07:05 AM	#8
rahnos18 ninjette.org member Name: Steve Location: Adelaide Join Date: Dec 2015 Motorcycle(s): 2008 NINJA 250R Posts: 14	downsizing jets is looking like my only option, I was hoping to smooth out the power without dropping a jet size. because of my long gears (mostly hwy riding), I wanted more juice there for the weekends, oh well I'll start looking in to who stocks jets, near me. if there's any ideas that haven't been mentioned, let me know please guys! thanks for the replys!

September 13th, 2016, 08:56 AM	#9
RacinNinja Vintage Screwball Name: B Location: Washington Join Date: Feb 2016 Motorcycle(s): 2011 Ninja 250, 2008 Ninja 250, 2019 KTM 1290SDR, 2017 FZ10 Posts: A lot. MOTM - Mar '16	Most likely your main jet is actually too small. With the K&N and a slip on, you need to go richer. If you're sputtering at high RPM's, this is an even greater sign. If it were me, I'd try a 105 or a 108 and see if it's better. If the jets use Keihin numbers, the 48 pilot is too big. Stock is 38 so I'd go with a 40 or maybe 42. __________________________________________________ Goin' fast on slow bikes!

September 13th, 2016, 09:15 AM	#11
Triple Jim Guy Who Enjoys Riding Name: Jim Location: North Carolina Join Date: Jul 2016 Motorcycle(s): Ninja 250 Posts: A lot. MOTM - Oct '18, Aug '17, Aug '16	You should be able to move the enricher (starter) lever when the problem is happening, and add a little extra fuel. If the problem gets worse, you're already too rich. If it gets better, you're too lean. I know this works with plain Mikuni round slide carbs, so I assume it would work with these.

September 13th, 2016, 09:47 AM	#14
RacinNinja Vintage Screwball Name: B Location: Washington Join Date: Feb 2016 Motorcycle(s): 2011 Ninja 250, 2008 Ninja 250, 2019 KTM 1290SDR, 2017 FZ10 Posts: A lot. MOTM - Mar '16	Since there isn't any relevant info in the jetting database thread for newgens other than pod filters, maybe after the last track day of the season Friday I'll tear my carbs down and see what the jets are. They should be looked at anyway and cleaned out/dried for the winter. It has stock airbox, no snorkel, K&N filter and a pipe. Dyno sheet shows it dead nuts on the money. I'm betting it doesn't have 100 mains in it. Then again, the OP is using a random Ebay carb jet kit. Who knows what the numbers actually are in relation to jet size. __________________________________________________ Goin' fast on slow bikes!

September 13th, 2016, 03:36 PM	#16
Triple Jim Guy Who Enjoys Riding Name: Jim Location: North Carolina Join Date: Jul 2016 Motorcycle(s): Ninja 250 Posts: A lot. MOTM - Oct '18, Aug '17, Aug '16	The enrichers aren't very effective with the throttle wide open, so you may have to pull it all the way to see much difference.
	1 out of 1 members found this post helpful.

September 13th, 2016, 03:40 PM	#17
rahnos18 ninjette.org member Name: Steve Location: Adelaide Join Date: Dec 2015 Motorcycle(s): 2008 NINJA 250R Posts: 14	ok, I'll try it in stages and let you guys know, might give a hint as to how lean it may be.

September 17th, 2016, 04:47 AM	#19
Lazarus ninjette.org member Name: RJ Location: PA Join Date: Dec 2015 Motorcycle(s): 2008 Ninja 250 Posts: 210	It is possible but might be more of a pain in the behind than just pulling the carbs and swapping them. Never tried it but you could remove the starter temporarily to give you a little more room to work with the carbs still in. Just a thought..

September 17th, 2016, 06:26 AM	#20
Triple Jim Guy Who Enjoys Riding Name: Jim Location: North Carolina Join Date: Jul 2016 Motorcycle(s): Ninja 250 Posts: A lot. MOTM - Oct '18, Aug '17, Aug '16	It's definitely hard to find an intermittent problem. The enricher lever idea is just a quick thing you do when you're actually having the misfiring. As you said, you don't want to ride around with it that way for any length of time.

September 17th, 2016, 03:58 PM	#21
LoD575 ninjette.org sage Name: Steve Location: Valdosta GA, US Join Date: Jul 2011 Motorcycle(s): 2012 Ninja 250, 2006 Ninja ZX6R-636 Posts: 661	You can change the jets without removing the carbs if you have a right angle adapter. It is still a tight fit, and can be a pain in the ass.