So I have a 2006 KTM 250sxf w/ fcr carb. The bike idles well, starts easy, has great throttle response, no bog. The only problem is when I'm putting around with no real load/no acceleration say 1-2 gear with the throttle rolled just above idle it sounds a bit rough. How should i go about trying to clear this up? which part of the carb?
Joined Nov 2001
17K Posts | 774+
Ely, England
I can't agree with the above.
you have the wrong jetting in your carb fella OK? you can purchase a kit off myself or search around this site for jetting that is a lot better.
the needle is wrong and the needle is the 'queen bee' of the hive.
regards
Taffy
you have the wrong jetting in your carb fella OK? you can purchase a kit off myself or search around this site for jetting that is a lot better.
the needle is wrong and the needle is the 'queen bee' of the hive.
regards
Taffy
Joined Jun 2007
4K Posts | 1K+
south east WA Australia
hi Jeep
you have an OBETP needle in there as stock?
have a read
carbkie.html, Keihin FCR Carb Tuning Procedures
for bike specific advice try asking here
Jetting and Fuel Injection mapping for 2 and 4 stroke KTM's
Needles wear out and moving the needle down a notch (clip up) can elevate the problem. I've had a few old bikes that developed the same symptoms and a simple needle clip adjustment temporarily fixed it.
I would recommend replacing the worn needle if the quick fix works.
My $0.02.
Don't crucify me for my opinion and experiences.
I would recommend replacing the worn needle if the quick fix works.
My $0.02.
Don't crucify me for my opinion and experiences.
Taffy, I don't mean to be rude but you can't offer a carb tuning kit that would work in all environments?
There is just too many variants like climate, altitude, fuel type, modifications and riders skill.
Although a standard spec carb kit would be better than something totally wrong.
Joined Nov 2001
17K Posts | 774+
Ely, England
firstly, jetting has nothing to do with the rider, it is to do with the engine and some of the stuff you said.
I don't jet for all environments. customers are required to tell me the state of tune of the bike, the CC, the altitude they ride at. fuel type only applies to the USA really.
the jetting is also 'only' done within a set destance and the customer is left to try and see if the extra 2% is available.
If I get the job 10% nearer than the manufacturer but leave a 2% error margin of safety I have done my job.
you'll find enough testaments on here to prove that my kit works. only 10-14 days ago someone posted how good it was.
and remember that that is the jump from a standard set up to my kit so from the wrong jetting just to standard will be what you are talking about.
Taffy
regards
Taffy
I don't jet for all environments. customers are required to tell me the state of tune of the bike, the CC, the altitude they ride at. fuel type only applies to the USA really.
the jetting is also 'only' done within a set destance and the customer is left to try and see if the extra 2% is available.
If I get the job 10% nearer than the manufacturer but leave a 2% error margin of safety I have done my job.
you'll find enough testaments on here to prove that my kit works. only 10-14 days ago someone posted how good it was.
and remember that that is the jump from a standard set up to my kit so from the wrong jetting just to standard will be what you are talking about.
Taffy
regards
Taffy
Joined Nov 2012
2K Posts | 821+
Iceland
before/after dyno graph?
also, before picking up a kit, people are encouraged to read up on standard practice and commonly available knowledge, and to check if the behavior of the bike actually matches the description in reviews and that of other owners (e.g. a Husaberg being "jerky, nasty, unrideable" IS NOT CAUSED by the lack of a jetting kit - these bikes are smooth and strong and linear out of the box and properly adjusted. This motor character is one of the things they are famous for.)
NONE of the 450/550/650 Husabergs I have ridden have had anything but OEM jetting and all carbureted very well. Strong and linear. Except for one 650 which was a bit jerky but a simple carb cleaning and simple fuel screw adjustment according to the manual fixed it. First things first!
The fuel screw REALLY does make a difference!
Jet kits can work fine. A JDjetting kit did wonders in my DR-Z. But they are not a panacea, they are not rocket science, and not a substitute for normal maintenance. Only a convenience. It can be good to not have to worry and wonder and just buy access to knowledge, even though ordering parts is quite fast and easy.
but I'd personally have an easier time believing in kits that have at least some empirical data backing them up.
also, before picking up a kit, people are encouraged to read up on standard practice and commonly available knowledge, and to check if the behavior of the bike actually matches the description in reviews and that of other owners (e.g. a Husaberg being "jerky, nasty, unrideable" IS NOT CAUSED by the lack of a jetting kit - these bikes are smooth and strong and linear out of the box and properly adjusted. This motor character is one of the things they are famous for.)
NONE of the 450/550/650 Husabergs I have ridden have had anything but OEM jetting and all carbureted very well. Strong and linear. Except for one 650 which was a bit jerky but a simple carb cleaning and simple fuel screw adjustment according to the manual fixed it. First things first!
The fuel screw REALLY does make a difference!
Jet kits can work fine. A JDjetting kit did wonders in my DR-Z. But they are not a panacea, they are not rocket science, and not a substitute for normal maintenance. Only a convenience. It can be good to not have to worry and wonder and just buy access to knowledge, even though ordering parts is quite fast and easy.
but I'd personally have an easier time believing in kits that have at least some empirical data backing them up.
Joined Nov 2001
17K Posts | 774+
Ely, England
a dyno graph for only the needle and one run only can be seen on ebay.
the people who use my kits are replying honestly and objectively to what they found. they are independant and nobody has put them up to it.
I'm sorry you don't like that and that you have felt forced to make small the skill it took to make the kit.
your points are undermined by the paucity of your argument. argueing with you is like talking to planctun.
Taffy
the people who use my kits are replying honestly and objectively to what they found. they are independant and nobody has put them up to it.
I'm sorry you don't like that and that you have felt forced to make small the skill it took to make the kit.
your points are undermined by the paucity of your argument. argueing with you is like talking to planctun.
Taffy
Joined Aug 2009
1K Posts | 346+
Charters Towers, Australia
Try in/out 1/4 turn at a time on the fuel screw first mate, if that doesn't make a difference try raise/lower the needle, these things cost nothing and you can learn a lot by just having a fiddle. If you can't feel a difference go to an expert.
In no way was I saying your jetting kits are a bad thing, in fact I think it's great for people who don't understand how to jet a carburetor correctly.
As for your comment " argueing with you is like talking to planctun." Well that's just childish. We all can have an opinion here without getting upset. It shouldn't be Tuffy's way or the highway.
Cheer up fella and keep up the good products and advice.
Joined Jun 2007
4K Posts | 1K+
south east WA Australia
it is not hard to improve on stock jetting by 10%, how much that is actually worth is up to the rider
price is down from nearly 100GBP ?
here is an ebay graph it has nice curves, what needle is the first run ?
KTM PERFORMANCE JETTING KIT reduced pricve!!!! 400 XC EXC SX (KEIHIN FCR carb) | eBay
price is down from nearly 100GBP ?
here is an ebay graph it has nice curves, what needle is the first run ?
KTM PERFORMANCE JETTING KIT reduced pricve!!!! 400 XC EXC SX (KEIHIN FCR carb) | eBay
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As an eBay Associate we earn from qualifying purchases.
Joined Nov 2001
17K Posts | 774+
Ely, England
the price was only ever 91gbp. the Husaberg kit has been 82gbp for several months since I found cheaper Pilot screws but I never have enough time to sort out the KTM jetting costs and anyway, my veins course blue and yellow and I chuckle at my wayward efforts when it comes to Orange.
I don't care!
just got off the phone from a KTM 625LC4 owner. thank christ his is flying, he does a lot on KTMUK and I don't need another troll........
that graph was one run. that is it! one run! there is NO other jetting change there, just a needle change. he didn't even move the needle - one run nothing else. the needle cost him 30gbp and he reckoned it was the cheapest 1.5bhp he'd ever had in 15 years of racing, far from being pissed he was ecstatic!
the needle is always the secret. for me, Sparks summed it up:
“Been out for a 2 hour blast this afternoon using your needle,
what can I say man, I think it is the dogs bollocks,
The idle is as steady as a rock, I think best ever, good off the bottom end (and) good mid range, and goes like f*** top end.
The roll on - roll off is also good, no harshness as I call it.
.......a needle made for the engine, not a needle made for the carb!
Steve Hardaker (Bradford Ignitions).
Steve and I used to discuss all this stuff and he pointed out that the Keihin PAS ratios DON'T match that which Keihin claim. That is why I gave it to him first to try, because I can trust him.
Taffy
I don't care!
just got off the phone from a KTM 625LC4 owner. thank christ his is flying, he does a lot on KTMUK and I don't need another troll........
that graph was one run. that is it! one run! there is NO other jetting change there, just a needle change. he didn't even move the needle - one run nothing else. the needle cost him 30gbp and he reckoned it was the cheapest 1.5bhp he'd ever had in 15 years of racing, far from being pissed he was ecstatic!
the needle is always the secret. for me, Sparks summed it up:
“Been out for a 2 hour blast this afternoon using your needle,
what can I say man, I think it is the dogs bollocks,
The idle is as steady as a rock, I think best ever, good off the bottom end (and) good mid range, and goes like f*** top end.
The roll on - roll off is also good, no harshness as I call it.
.......a needle made for the engine, not a needle made for the carb!
Steve Hardaker (Bradford Ignitions).
Steve and I used to discuss all this stuff and he pointed out that the Keihin PAS ratios DON'T match that which Keihin claim. That is why I gave it to him first to try, because I can trust him.
Taffy
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Look I don't want to upset people when I comment but I enjoy a good disagreement, that's how problems are solved best. We all have different ideas/thoughts and it helps to branch out to many solutions to one problem. As Taffy said the needle is the queen bee of a carburetor and I agree. IMO first clean the carb, if the bike was running ok and the clean didn't help then new jetting will not help, it must be something else?
I was only giving advice on my own experiences. I've had previous owners of bikes that have some how bent the slide needle enough for it to wear away and cause partly open throttle problems.
The thicker part of the needle wears and let's more fuel then needed past the main jet at the slightest twist of the throttle.
There is only a few moving parts in a carburetor, one is the bowl float and needle and the other is the slide and needle which does more work then any other part and is more prone to wear, too many people often over look this.
The slide needle wears in a way that it thins where it makes contact and does not above that point, creating a plug at idle, as soon as the throttle is turned slightly it exposes the worn needle and too much fuel is released causing a rich mixture.
I know the main jet and needle is not meant to effect the first 1/4 of throttle movement but wear and tear can make this happen.
Again Taffy's carb kit could fix this(it does include a needle right?). There is nothing more valuable then experience.
I was only giving advice on my own experiences. I've had previous owners of bikes that have some how bent the slide needle enough for it to wear away and cause partly open throttle problems.
The thicker part of the needle wears and let's more fuel then needed past the main jet at the slightest twist of the throttle.
There is only a few moving parts in a carburetor, one is the bowl float and needle and the other is the slide and needle which does more work then any other part and is more prone to wear, too many people often over look this.
The slide needle wears in a way that it thins where it makes contact and does not above that point, creating a plug at idle, as soon as the throttle is turned slightly it exposes the worn needle and too much fuel is released causing a rich mixture.
I know the main jet and needle is not meant to effect the first 1/4 of throttle movement but wear and tear can make this happen.
Again Taffy's carb kit could fix this(it does include a needle right?). There is nothing more valuable then experience.
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Joined Jun 2007
4K Posts | 1K+
south east WA Australia
91gbp is BS taff you had it listed for 99GBP for years
if you search this forum for jetting there are an enormous number of positive reviews about Dale lineaweavers needle and jets
the exception being that a few people found the needle straight to be too rich
hes not making them any more but you can get a honda needle that is almost the same except for the needle straight being slightly leaner
NEEDLE SET, JET (NKBT) (16203-KRN-A01) they go for about 20 USD
i like it i have one in my 700 and i made my own needle for the 628
pics here
http://husaberg.org/mechanical/17998-bushmechanic-mongrel-628-trailbike-14.html
if you search this forum for jetting there are an enormous number of positive reviews about Dale lineaweavers needle and jets
the exception being that a few people found the needle straight to be too rich
hes not making them any more but you can get a honda needle that is almost the same except for the needle straight being slightly leaner
NEEDLE SET, JET (NKBT) (16203-KRN-A01) they go for about 20 USD
i like it i have one in my 700 and i made my own needle for the 628
pics here
http://husaberg.org/mechanical/17998-bushmechanic-mongrel-628-trailbike-14.html
Last edited:
Joined Apr 2014
689 Posts | 252+
Chilliwack, BC, Canada
Just came across this and have to comment. I keep hearing this crap about "Jet Kits"
Now lets get into reality
"The Magic Beans"
IMO,
A jet kit does absolutely nothing for you unless you are drag racing your bike through the quarter mile and want to shave off a hun of a second and some how hope " The Magic Beans" do it for you. It is like hearing the guy who has a new or replaced power band Ha-Ha
A jet kit does not make you ride better.
A jet kit is not magic in a box.
A jet kit will not make you faster through that single track or on the straightaway.
A jet kit will do absolutely nothing for you unless you are in the top 1% of professional riders and need that teeny little bit to help gain that edge and happen to have a dyno at your finger tips in your professional race shop for your crew to tune your bike with.
Reality,
A jet kit or the "Magic Beans" will help if your bike has been screwed around with by those who like to tinker and or prior owners. Factory jetting is and has been proven by engineers that design these machines.
Should your bike be used at an altitude that the bike was not designed for.
Should you have extra money to replace pistons and valves that get burnt by shops that guess your conditions and believe they have a crystal ball and answers to your problems.
There is no such thing as a perfect jetting out of the box. The only way one can find this is to have all jetting available and a dyno at hand at all altitudes and spend days tuning. This is fact as ones dyno run will not be another's. I can claim to have 1500 horsepower in my dragster that has been dyno'd at my shop and runs 6.50 at 212MPH and proven with my jetting and or mapping. I sell it to you and you live somewhere else at the same altitude, I can guarantee the dragster will not run 6.50 at 212mph. It could be faster or slower be will not work the same.
The combinations of Driver, Temperature, and every other than imaginable thing that can fall into place can and will.
Ever heard of a placebo or the placebo effect. I put fancy special racing tires on for the rain so you gonna be able to ride faster now, and then you do. The tires were the same but someone told you they were special and you felt them perform.
Tune your bike to factory specs and make sure you do it by the book and correct and your bike will perform like no other.
With exception of the extreme changes in altitude and or the prior guy who changed things.
No need for needles, jetting misc. Just spend your time riding and getting better at it yourself and the guy who has those fancy "Magic Beans" will be in the dust.
Food for thought lol
Now lets get into reality
"The Magic Beans"
IMO,
A jet kit does absolutely nothing for you unless you are drag racing your bike through the quarter mile and want to shave off a hun of a second and some how hope " The Magic Beans" do it for you. It is like hearing the guy who has a new or replaced power band Ha-Ha
A jet kit does not make you ride better.
A jet kit is not magic in a box.
A jet kit will not make you faster through that single track or on the straightaway.
A jet kit will do absolutely nothing for you unless you are in the top 1% of professional riders and need that teeny little bit to help gain that edge and happen to have a dyno at your finger tips in your professional race shop for your crew to tune your bike with.
Reality,
A jet kit or the "Magic Beans" will help if your bike has been screwed around with by those who like to tinker and or prior owners. Factory jetting is and has been proven by engineers that design these machines.
Should your bike be used at an altitude that the bike was not designed for.
Should you have extra money to replace pistons and valves that get burnt by shops that guess your conditions and believe they have a crystal ball and answers to your problems.
There is no such thing as a perfect jetting out of the box. The only way one can find this is to have all jetting available and a dyno at hand at all altitudes and spend days tuning. This is fact as ones dyno run will not be another's. I can claim to have 1500 horsepower in my dragster that has been dyno'd at my shop and runs 6.50 at 212MPH and proven with my jetting and or mapping. I sell it to you and you live somewhere else at the same altitude, I can guarantee the dragster will not run 6.50 at 212mph. It could be faster or slower be will not work the same.
The combinations of Driver, Temperature, and every other than imaginable thing that can fall into place can and will.
Ever heard of a placebo or the placebo effect. I put fancy special racing tires on for the rain so you gonna be able to ride faster now, and then you do. The tires were the same but someone told you they were special and you felt them perform.
Tune your bike to factory specs and make sure you do it by the book and correct and your bike will perform like no other.
With exception of the extreme changes in altitude and or the prior guy who changed things.
No need for needles, jetting misc. Just spend your time riding and getting better at it yourself and the guy who has those fancy "Magic Beans" will be in the dust.
Food for thought lol
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