KTM 520EXCessive power 4U

[James Dean]

If any 520 riders can't get enough power. here is your fix :eek: -

Replace the stock OBDTM#2 needle/175 main with an OCEMN#4/168 main.

There will be an instant boost in your power from 1/4 throttle up. More snap at the throttle to loft your from wheel at any time. It works in the 400 also.

----------------------

The needle has more taper which requires a smaller main jet to keep the full throttle jetting unchanged. Leave the pilot (#48) and pilot screw unchanged (about 1-1.25 turns out).

This is a STANDARD TAPER needle for the Keihin FCR carb. It is very close to what the YZ426 and 250F have. The stock needle simply runs extra lean in the midrange. It can be purchased from Sudco at 1-800-998-3529 or Carb Parts Warehouse or your dealer can get it from them.

Have fun and Hang On! ;)

James Dean

 

[JohnnyMac]

I'll give it a try in my 520sx this weekend. What clip position should I try as a starting point?

I ride at about 3,000 ft.

 

[Roost Man]

James Dean,

Is the needle normally available at a KTM dealer??
Should I run the same jetting at 1000-2000 elevation, 85 - 100 degrees??

Thanks :think

 

[James Dean]

That was clip #4 (EMN#4), but if it feels too rich down low switch to #3.

The needle is not a KTM OEM option. It should be.

There has been a great deal of testing and evaluation of jetting with the FCR carb on Yamahas, KTM's, and a few Suzuki's. I've received feedback from riders all over the world. The different combinations of needle diameter, taper, and clip position were all compared. This carb needle is the best all-around choice that I've found. If you're at high altitude EMP is a step leaner, then EMR is another 2 steps leaner after that.

When you get the big jump in power, call up your KTM rep and tell him that James Dean gave you the tip and is willing to do a little new bike testing/consulting on the side. ;)

James Dean

 

[JohnnyMac]

Thanks James Dean,

Can't wait to give it a try. I neglected to mention I also run a pro circuit silencer. Will this have any effects on your recommendations?

 

[James Dean]

JohnnyMac,

With the PC silencer try #4 first and think about clip #5 as a possible option of you have any extra time to test. The more open exhaust may run slightly better with it.

James

 

[JohnnyMac]

Looks like I'll have to postpone my ride report. "Sudco" and "Carb parts" are both out of stock on the needles.:(

 

[Strick]

JohnnyMac, the short supply is James Dean's fault. So many riders have taken his sage advice that there is none left:(

Also there is a rumour that James has purchased all the available needles and will the selling them for $25 each, plus shipping:p

Just funnin'

James you are the jettin' MAN!!!:cool:

 

[trl junkie]

Cool! Thanks for the information. As soon as these parts are in stock, I will buy them and put them on.:)

 

[drehwurm]

Servus James,

OCEMN#4/168 main

Do you really mean OCEMN and if yes, where is the difference between OB and OC neddles?

Actually I can't imagine handling more power on my 520, but if it is there ...

Michael

 

[brettv]

I am not very carburator savy. Is this something I can do myself with the manual? So I need to pull out the existing needles and replace them with the OCEMN#4/168 main. IS there any other adjusting that will need to be done?
thanks for any info.

 

[Shaw520]

Originally posted by drehwurm
Actually I can't imagine handling more power on my 520, but if it is there ...

I HEAR that,.... you can always opt for the optional NHRA braking chute to slow ya down for the corners,..!! :D
However,....if there is a jetting advantage to be had,.... Jimmy D. will find it! :cool:

 

[James Dean]

Does Orange Go with Blue?

Drehwurm,

The OC needles are made from brass and the stock OB are an anodized or plated aluminum.

If you REALLY want an OB needle, Yamaha ( :think ) has a part # 5JG-14916-EN which is OBEKN. This is 1 clip richer, so will need a setting of clip #3 rather than #4. Cost is about $15. Wouldn't it just make you sick to use a part from a blue bike? :think

Brettv, If you can get the carb off, you can do it. We left the pilot and pilot screw untouched. (A hard thing for me to accept. :D )

I guess Sudco should stock up on these FCR needles.

James

 

[BENT]

Mr. Dean,
Is all the information the same for a 400?
BENT

 

[drehwurm]

Re: Does Orange Go with Blue?

Servus James,

Believe it or not, but my 520 is already BLUE! I even put Yamaha fork guard stickers on it - still miss my WR a little.

If you REALLY want an OB needle, Yamaha ( :think ) has a part # 5JG-14916-EN which is OBEKN.

Honestly, after pondering about this a little I will not start this jetting stuff again - this bike works so fine engine wise, there just is no need to! And I'm busy with the suspension anyway :confused:

We left the pilot and pilot screw untouched. (A hard thing for me to accept.

My dealer put in a 52 pilot right from the start and what should I say - just see above!

Thanks!

Michael

 

[James Dean]

BENT, yes the change works in the 400 as well with the same settings. The clip position is most likely #4, or possibly #5 on a free flowing SX exhaust.

drehwurm, If you decide to do this at a later time, be sure to use the #48 pilot jet. How many turns out is the pilot screw with a #52? No choke to start it cold? This sounds like a compensation for the (lean) #2 clip position. If you get a chance, be sure to try it. More power with controlled manners is hard to pass up. Cost will be minimal.

James

 

[RetSenior]

James, My 520 EXC runs awesome with the stock carb settings but I'm willing to try the needle & jet if the needle ever becomes available just to see the difference. I too have it backordered from Sudco.

 

[PeterEXC520]

Re: Re: KTM 520EXCessive power 4U

Hi Michael,

Originally posted by drehwurm
Servus James,



Do you really mean OCEMN and if yes, where is the difference between OB and OC neddles?

Actually I can't imagine handling more power on my 520, but if it is there ...

Michael

I tried the needles (on both type of KTM 400 and 520). Nice improvement but my 520 was jetted this way: Main: #175 pilot: #52
Exhaust: Biggun Full Race or quiet series

Peter

 

[James Dean]

Peter,

Thanks for adding your settings. What needle clip positions did you use on each? and pilot screw turns?

The exhaust may be more free flowing than stock, in which case richer jetting may be needed.

I also wonder about differences in fuels.

James

 

[PeterEXC520]

Hello James,

Originally posted by James Dean
Peter,

Thanks for adding your settings. What needle clip positions did you use on each? and pilot screw turns?

The exhaust may be more free flowing than stock, in which case richer jetting may be needed.

I also wonder about differences in fuels.

James

Clip position 5 and pilot screw turns like KTM recommends on both bikes. I'll try a #168 main on the 400 because this bike is completely stock.
Peter

 

[bultaco290]

Mr dean

I have a 520mxc 2001 and I'm having a hesitation or cough right off idle do you think that this jetting change will eliminate this problem think

 

[KTM400MAN]

Hi James, So Cal Erik(Thumpertalk) here, and I saw this post so I went out to my garage, and looked at my old collection of Sudco needles used on my old 99WR-400 (back when you and everybody else was into needle experimentation on the WR's) and what-do-you-know?! I just happen to have a ocem-n needle!!! I will try it out ASASP on my KTM 400SX and let you know what settings and results I come up with. I have been racing MX with the Over The Hill Gang and finishing on the podium(so to speak) at my last 4 or 5 races, so any improvement is greatly appreciated. I currently run a 170 main, dropped the stock needle 1 clip from stock, and run the stock pilot 1-1.25 turns out.
It ran great at Gorman after I dropped the needle, but I'm going to Sunrise, or Perris on Sat., so I'll have to adjust the new needle accordingly then.
By the way, I'm racing at the OTHG Mammoth mx in June, will the new needle help me out at high altitude too? (9,000 ft.)or would the stock needle work better since it is leaner?? Erik

 

[James Dean]

Bultaco290, Try a richer clip, backing out the pilot screw a little, and a slightly faster idle. The needle will help, but a significant cough will need more than just the needle.

Erik, The EMN needle will be on the rich side at 9000ft, the DTM will be easier to adjust with the pump flowing longer than required typically. The main jet should be reduced substantially. The stock YZ426 is using #162 and you may want to be down that far or more also. Possibly clip #3, but not sure.

James

 

[bultaco290]

one who is truly wise in the ways of jetting

Hey James,

Just to make sure we are on the same page when y0u say try a richer neddle does that mean frop the clip on the neddle down one? Should I still try the above mentioned jetting first?

 

[colorado-high]

MR.Dean would it be possible to post a complete list of your needle and jetting changes for different altitudes?Seems like it would be easier to tell people to go to one page that they could print out instead of trying to look thru each post to find your recomendations.IMO. Thanks for all the great help.