KTM 950 Jetting Database

Discussion in 'Dakar champion (950/990)' started by Billroy, Jan 11, 2006.

  1. Xcelite

    Xcelite Been here awhile Supporter

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    There aren't a whole lot of high elevation mappings in here so i'd like some expert opinions on jetting changes. Bike is an '04 with FMF exhaust, no emissions stuff. Driveway is 5,200ft. Typical rides are 4,000 - 8,000ft. Extreme elevations in NM are down toward 3K and up to 12-13K ft.

    Currently, the bike runs well with the following:
    Stock air box with pre-filter instead of snorkel
    Mains - 145/148
    low spd - 42
    IAMS - 2.5 turns (roughly) It was difficult to tell with the flex jets.
    IAJ 70/70
    needles are NDFB on middle clip. So the third out of five settings.
    Floats are 3mm

    I am putting on the Triple Clamp Moto open air filter kit. After reading through here for quite a while, here's what I am thinking of switching to:
    Mains - 160/162
    low spd - 42
    IAMS - 2 turns
    IAJ - 70/70
    needles are NDFB on middle clip. So the third out of five settings.
    Floats - 3.5mm

    Is there anything sticking out like a sore thumb with the proposed new settings or am I on the right track?
  2. opanos

    opanos Been here awhile

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    why people keep putting needle clip on 3rd notch?
    still dont get it...
  3. Xcelite

    Xcelite Been here awhile Supporter

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    Well, for starters, the instructions on the new intake recommend it. And I don't know any better. I suppose I'll have to do more reading as to why it is often recommended.
  4. Zuber

    Zuber Zoob Supporter

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    I'm not a fan of the 'teddy bear' filters. Tough to jet.

    I'd just pull off the pre-filter and put the snorkel back on. Then for your altitude the stock mains 155/160 and stock needle clip would be about right.
    3.5 float is good.
    42 lsj.

    Then try IAMS at 3/4 to 1 turn out. When you start it up cold, turn off the choke right away. It should run like crap. If it still runs good, then the IAMS are too rich.
  5. DaviG117

    DaviG117 n00b

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    So your saying that it's a good sign if your bike runs slightly poorly from a bone cold start. Because my bike currently runs poorly from cold with a lower idle speed then when it's up to temperature it runs better with a higher idle speed. (An idle speed at which it should be at)
  6. bobnoxious67

    bobnoxious67 Baby steps...

    Joined:
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    Harrisville, NH
    Typical ‘what should I change jetting to" post, having a hard time finding a listed setup that sounds the same as mine:

    Triple Clamp air filter setup, full twin Akro’s with DB inserts, sea level-3500’. I have bad surging at part throttle, especially at highway speeds, and it likes to fall on it’s face when winding it through the gears hard from low rpms and gears (like one carb is having a hard time transitioning or something). Stock jetting throughout, starts fairly easily warm or cold, wants some/most choke cold.

    I need to swap out the combined ‘y’ vent, but any recommendations on what jetting to throw in there? Surge was less noticeable with stock air box, and is unbearable now along with the falling on it’s face with the open air filter.

    Thanks.
  7. nk14zp

    nk14zp Long timer

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    Post 350 is the jetting I plan on using when I swap my air filter over. I'm running SBKs without inserts on my adv tho.

    https://advrider.com/f/threads/new-...tem-development.1365319/page-18#post-38088387
    bobnoxious67 likes this.
  8. bobnoxious67

    bobnoxious67 Baby steps...

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    Location:
    Harrisville, NH
  9. Xcelite

    Xcelite Been here awhile Supporter

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    Finally got out to test ride today. New TripleClamp intake with the following settings at 5,000+ elevation. Dual FMF exhaust and no emissions.

    Mains - 155/160
    low spd - 42
    IAMS - 2.25 turns
    IAJ - 70/70
    Stock needles, 2nd clip.
    Floats - 3.5mm

    Seemed to run great. No loss of power or throttle response that I could find. 2nd gear roll-on to 9K RPM and it never felt like it was flattening out. I still needed to open the enricher to start it and it very nearly died when I shut that off after a few seconds. I opened it back up just a tad to let it finish warming up. It was about 70 degrees ambient temp for that.

    I tried putting it in a higher gear while going slower, maybe 25mph in 3rd gear, and then ripping the throttle open. It didn't bog down like it was flooding. It just kept chugging along with a low rumble. So now i'm wondering if the jetting is still a bit lean. I was expecting the bike to bog down with too much throttle. Also, the IAJ's were at 70 when I got the bike. Should I put those back to the OEM size 50 for any reason?
  10. Velric

    Velric n00b

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    Hello, I would like to get some expert opinions for a 5,000 ft elevation, warm climate 20-30c jetting, Uni Pre filter and K&N filter, Stock exhaust, all emissions stuff has been removed.

    Currently was running on the next config,

    Mains - 155/160
    Low Speed Jet – 42 (the back one was/is broken)
    IAMS - 3 turns
    Stock needles, 1nd clip.
    Floats – 2.3mm

    On cold stars I had to use the “idle adjustment knob” for it to not turn off and after It had harm up I had to adjust again to rev it down on idle (the choke doesn’t hold is position for some reason). Also the bike had a dip in power around ¾ of the revs

    Note: I have already order a new Low Speed Jet, so I will be running with 45 that came with the FactoryPro Kit in the meantime.


    For what I have read I should be running something like this right?

    Mains - 155/160
    Low Speed Jet – 42
    IAMS – 2 1/4 turns
    Stock needles, 2nd clip.
    Floats – 3mm

    Any advice is more that welcome.
  11. HiOctaneOverland

    HiOctaneOverland Been here awhile

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    I've had my 950 SE for a couple of years and always been happy with the fuelling - until a mate of mine bought one which had been set up by some sort of Carburettor God and is absolutely sublime. So, realising how good good can be I've started to go through the fuelling on my bike to see if I can make any improvements.

    The bike has a standard airbox and all the emissions plumbing removed or blocked off. I live just above sea level (about 200ft) in a temperate climate (10-25C). When I bought it the bike had standard KTM cans which I changed for twin Akra's running with dB killer inserts. After a few hours of spannering, here is what I can report:

    The floats are about right. The standard OEM KTM 3mm gauge just touches the floats, so I guess they're about 3.2mm or thereabouts.
    Mains 155/160
    Idle and starter 68/42 both
    The IMS was somewhere I couldn't work out. About 3 turns for one and 2.75 the other, so I reset both to 2.25 so I have a datum position.
    Needles were both on 2, having changed the bike to Akras from standard I raised them both to 3, although note I'd already reduced the IMS a tiny amount.

    Also, all the jets in the float bowl (main, starter and idle) went through my ultrasonic cleaner. Modern fuels with all the additives, ethanol etc do jets no favours so a quick clean can only be beneficial.

    Does the bike ride any different? Well, it's always great when it starts after stripping the carbs, right? It needs enrichment to start and for initial idle, but none when warm - that sounds about right. The bike pulls like a train with no hesitation or stumble and has a slight exhaust burble when the throttle is shut from high or moderate power. I haven't done enough miles to assess fuel economy, but they're only a small adjustments so I expect little or no change.

    Overall, I'm happy, it's a delight to ride especially compared to an injected 990 - but it's still not as good as the good I've seen.
  12. braaap!

    braaap! Long timer Supporter

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    Probably because '3rd' notch works for the rest of the world... Maybe just not Rotterdam... @below(?) or at Zee level :)
    Just tugging your chain @opanos ;)

    I'm on 3rd clip with meine Rottweiler intake... Soon to switch to a fresh TCM intake... Will see what changes manifest or not, but right now my old 950 roars and pumps along intoxicatingly!
    Pulls hard and clean off idle to WOT, pops and farts on decel but who cares?
    Fuel economy be damned!

    :)
    bigborett likes this.
  13. Xcelite

    Xcelite Been here awhile Supporter

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    I'm farther north than you are but still at 5,000 feet elevation. With those stock mains, I imagine you are running rich. Here's what my bike had before I put on an open intake:

    Stock air box with Uni pre-filter instead of snorkel, dual FMF exhaust, no emissions.
    Mains - 145/148
    low spd - 42
    IAMS - 2.5 turns (roughly) It was difficult to tell with the flex jets.
    IAJ 70/70
    Stock needles, third clip.
    Floats at 3mm
  14. HiOctaneOverland

    HiOctaneOverland Been here awhile

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    I have an update.

    Having said in my original post this bike could be better, I’ve changed my mind. I’ve ridden it for a few more miles and decided actually it’s pretty perfect. It starts on just one touch of the button, needing enrichment when cold but none when hot. It pulls like a train and never stumbles. Jets, IMS and needle settings are all perfect for the conditions and Akra cans.

    Happiness is a well tuned 950SE.
  15. singlewideteamusa

    singlewideteamusa Been here awhile

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    Jul 22, 2011
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    Location:
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    Hello all,
    Searched through this thread for symptoms similar to my situation, didn't come up with a concrete solution so thought I ask the collective.

    My Super Enduro runs awesome, wheelies easily, hasn't got any noticeable flat spots or hard starting issues. It does however have a slight (annoying) hiccup when holding steady throttle at about 3500-4500 rpm. Almost like a tiny backfire or the ignition is flipped off for a micro second. It's accompanied by a clicking sound from the carburator area. Been tough to diagnose as I can't duplicate it on a stand and riding with my ear by the carbs has proven to be a little dicey. :fpalm

    Any thoughts or ideas are appreciated, here's my carb setup.

    Needles stock 2nd clip thin shim under
    170/175 mains
    Floats at 3mm
    45 pilots 2 turns out
    1100 feet elevation
    Vacuum fuel pump
    Dual Remus
    Emissions gone
    ITG filter. (Soon to be Triple Clamp setup)
    Worn out rear tire
  16. Velric

    Velric n00b

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    Aug 10, 2018
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    2
    Location:
    Mexico
    Hello again and thanks @Xcelite I will order smaller mains to test, currently I only have bigger mains that stock, But while testing bigger mains I found something weird, is recommended to put the bigger main on the rear carb right? But I didn’t know that and I assume the bigger main went on the front carb cuz it runs cooler so is has denser air so it need more fuel as a result… and that I did, the bike was able to power wheelie for the first time, it run great on the top end but still not perfect had hiccups around 8k RPMs. Then I read on this forum that the bigger main goes on the rear carb and so I made the switch, but it now runs worst that before no more power wheelies. My question is why? Does it make senses? Also note the IAMS is 3-3¼ turns with 42 pilot jets (test it to 2 turns but it show clear sings of being lean)

    ---edit grammar---
  17. GoGoGavin41

    GoGoGavin41 Waves to Moto Cops (and they wave back)

    Joined:
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    Here's a question:

    Triple Clamp intake, 2-1 Yoshi pipe, no emissions.
    Mains - 165/170
    low spd - 45
    Stock needles, third clip.
    Floats at 3mm (one was a little higher)
    Flex jets turned out 1.5 on one, 1 on the other (not sure which is front or rear)
    Getting ~30 mpg
    I live ~20 ft above sea level

    When on the throttle the bike pulls great, plenty of power through powerband (~5500 rpm, guessing as I don't have a tach) when accelerating wide open. Maybe a slight hesitation down low off of idle.

    Up at higher rpm & speed (think 5th and 6th gear above 60 or 70mph), any backing off the throttle from wide open the bike sputter and backfire almost like it's running out of gas. Even trying to get back on the throttle it'll hesitate and sputter a bit before the power kicks back in. It only seems to do this right in the normal sweet spot for power and when the bike is hot. Doesn't seem to do it in lower gears (1 - 4).

    This bike was tuned while there were big holes in the vacuum diaphragm, so I'm wondering if I need to run the flex jets out farther? Honestly I have very little idea of how to tune a carb and what a "lean" or "rich" condition sounds and feels like.
  18. albani

    albani Been here awhile

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    1. take a scribe and mark your flex jets. that'll cut out some of the confusion. (mine are labeled F and R with an arrow. The arrow lets me know when a full revolution has been made)
    2. document any changes you make. change one variable at a time. ie: fuel screws, needle position, jets, etc.
    3. road test it over varying conditions, and while the bike/carbs are warm. pull the fuel pump fuse when you get home and the float bowls won't be so full.
    Rich is boggy, at idle RPMs will sag then come back up. Exhaust smells like unburnt gas. Easy starting cold. Runs good cold, poorly when warm.
    Lean is flighty, aka surging. idle will shoot high then dip erratically. Low on power, hard to start cold. Runs good warm, poorly cold.

    From what I've read these bikes are prone to that surge feeling off throttle in 5th/6th. (go back 2 pages!) It took me a fair bit of trial and error to get that tuned out. There's an ACV diaphragm that cuts air to the pilot circuit under high vacuum as in decel operations. I'd recommend marking your a/f screws and set them to a baseline of 2.5. The rear cylinder runs hotter, set it to be a touch fatter than the front one.

    Plugs can be a good indicator, in cases like this it won't be a lot of help. If you have an IR gun, you can use that to tune your a/f screws at idle based on temperature of the exhaust header. (leaner is hotter!)

    I just actually altered the float heights from 2mm to 4mm. Seems to pull better in the midrange, no noticeable surging. The rear cylinder may be a touch lean at the moment and need some A/F adjustments.

    Rest of my settings are:

    needles #2.5
    Mains 175/180
    PJ 45
    Floats 4mm
    A/F screws +/- 2.5 turns out

    Intake: Tripleclamp
    exhaust: Dual FMF cans with arrestors fitted. No emissions systems.
    Fuel economy is 28-42mpg. It drinks like the QM2 in the dirt. 42 observed during winter snow/rains. Typ is 35-38 with now 7000 miles on this jetting. No issues from sealevel(home) to 8000'. At elevation the A/F screws are re-adjusted. (I'm always altering the settings on these two screws by +/- .5 turn...)
    GoGoGavin41 likes this.
  19. Zuber

    Zuber Zoob Supporter

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    I'd like to remind you all of a few tips.
    - The Throttle Position Sensor sets the ignition advance. The TPS voltage at idle should be 0.600v, between the yellow wire and black wire at 1400 rpm. If this is off, you may get a soft spot at about 3200-3800 rpm that feels like lean jetting.
    - The Low Speed Screw setting of 2.0 turns is just a starting point. If it runs better at 3 turns, you need a bigger Pilot Jet. More than 3 turns has little effect. I've found this engine to run better with a bigger Pilot Jet and the LSS at 3/4-1 turn out. These should be the same front/back. Otherwise, you may have a float setting off, vacuum leaks, valve clearance issues, etc.
    - Cold starting can give you good tuning tip-off. It should need full choke to start. It should die if you turn the choke off. The choke should feel progressive, if you close it slowly the idle should go progressively down. If you have a richer Pilot Jet with the Low Speed Screws about 1 turn, the choke will act like this.
    - You are running on the Low Speed Screws about 95% of the time, so these settings are very important. Get the Flex Jet remote adjusters. There is no way you can guess what the bike will need until it starts. I change these screws a lot. 3/4 turn in summer, more like 1 1/4 turn in winter. The screws and pilot jets determine your mileage.
    - These carbs are rich from the factory. You don't need to go much richer unless you add open mufflers and open up the airbox. The main jets are easy to set, the transition from idle up to 1/2 throttle is more difficult.
    GoGoGavin41 likes this.