Straight needle for KDX220?

[thegraydog]

Today I rode a KTM200. This is at 8000' where my new kdx is boggy, then explosive. The ktm has less top end than my kdx, modest and progressive throttle response, and I couldn't stall it even when I was idling through the rocks. Owner said it is due to a straight needle. I WANT THIS! Any advice? Help an old guy get up through the steps!

 

[thegraydog]

I spent half of Sunday reading the archives on this subject. Thanks to canyon carver, acutemp, JD .... Thanks to gearloose for the big rock method for tuning the airscrew -- I haven't had any sense of its effect and this ought to help.
Also read the long thread about the ktm200 vs kdx200. The fact that my experience of the two is exactly the opposite of expectations shows how much is possible with tuning and also the limits of advice, versus figuring it out.... My kdx will yet be the bike of my dreams.

 

[G. Gearloose]

Sounds like it can only get better for you.
Kudos for checking the wealth of knowlege already accumulated; good show!

 

[canyncarvr]

Hope you post your results.

Your friend could have done you a big favor by telling you which needle. ;)

As you likely know, the KTMs come with a dual taper needle generally. The last KTM200 I had anything to do with had an NOZH if I rememmer correctly.

Fishhead (formerly of the green persuasion) rides a pumpkin now. At least did awhile back. I think he had a lot to do with the orange crowd going to the 1º45' ('D') needles. He did a lot of ride testing with different needles, ended up with a DCK-2 last I heard from him.

I don't know if that would be called a 'straight needle' and if it is called that, I don't know why it would be. Big help, 'eh? ;) Maybe you could call a single taper needle 'straight' compared to a dual taper needle?

Keep in mind that a rec from a pumpkin rider may well be concerning an airstryker carb. The jet block in that pwk Keihin is different from the oem pwk on kdxs. It's higher by about 1mm I belive.

...Unless it's been modifed by RB-Designs. Ron lowers the jet block to get the jetting more 'in line' with other pwks.

My riding buddy's 200exc with the double taper needle was awful (my opinion). A change to a DEK-4 needle and relatively correct jetting (well, along with Ron's work!) made it into a different bike!

At 8000', a compression ratio increase (head modification) would be a huge benefit to you. You would get a lot of 'bottom end' help with that.

Still, with no modification other than a decent jet-set you will far ahead of where you find yourself now.

Good luck! You will find that jetting is more of a factor for your riding enjoyment than you ever considered possible.

If you haven't checked this thread , a read thru will give you a lot of needle info. You mention JD, so maybe you've already been there. The point is, just because it says 'Emergency RB-Designs jetting info needed' an oem pwk owner will still benefit from reading it.

Have fun!

Good show, indeed!

 

[thegraydog]

Steve says the ktm comes with a triple taper needle, which makes a rich low, leaner mid, and a violent hit thereafter. His straight needle is the DDK. Also prescribed with this is gearing up, from 48 to 45 teeth rear.

I ordered an AEQ needle from Sudco; next weekend I'll have an afternoon of jetting. If I don't get lucky on the first try I'll ask Sudco about it, and get a fistful. Five bucks apiece! Getting translated from Kawasaki to Keihin has been kinda frustrating, but once I get indexed I should be able to go up and down the chart to see what happens. Somewhere in the justkdx archives is the benchmark that BEL equals R1173L, more or less -- so I'm starting there.

 

[canyncarvr]

Uh...no.

The term 'triple taper' is not correct. It is used often to denote the geometry of the KTM style needle, but it is wrong.

The KTMs come with a needle that has two different tapers to it..thus they are double tapers....NOT triple. The only way you could conceive them to be triple tapers is if you count the actual STRAIGHT section as a taper.

That is in-line with calling the DDK a 'straight' needle. Obviously, it isn't straight 'eh? It DOES have a 1.75º or 1&3/4º taper. Oh..I wrote that as '1º45", or 'one degree, 45 second' angle before. That is not correct. Minutes come before seconds (last I checked), so it would be 1º45'. The " is for seconds, sixty of them in one minute, sixty minutes in one degree. Click if you care about any of that.

Whew...anyway......


An AEQ isn't going to work for you.

Read thru the thread I mentioned in the previous thread. Maybe you are unaware.... 'this thread' in the above post indicates a link to another thread. You will find lots of information you need there. Not everything in bold is a link...and indeed a link may not show up as anything particular unless you place the pointer over the text that indeed is a link.

Got that? ;) OK...so much for 'Forums 101'.

The 'A' needle family (1º0' taper) has been tried. Actually, there is ONE (no link here!) kdx'er that is happy with the AEN (I think it was) that RB-modified carbs used to come with. I've never understood the why of that...cuz it don't work for diddle, imo.

A DDK (probably clip 2) is right in-line with fishhead's notes for the KTM200.

JD has a spreadsheet that allows you to input jet info (pilot, main, needle and clip), throttle valve cut, temperature and elevation to show graphs of needle profiles and % of fuel delivery change.

It is a terrific tool for comparing different jet-sets to 'see' what will happen.

If you're interested, let me know.....I'll verify and send you the web address that offers it for sale. It's changed a few times...I don't want to list an old/bad addy and don't want to take the time verifying it if you aren't interested.

One last edit...

You mention 'frustrating' regarding Keihin-Kawi needle translation. I take that to mean you have not been to CDave's site? Listed on the top of this forum is a thread, 'Every kdx rider should read...' that has a link to CDave's Justkdx site. On his site he has a 'needle decoder' section that makes translation a snap.

Pictures and everything! Heck..even I understand it!

Something to keep in mind that (imo) is critical to understanding needles. The 'L1' or 'straight' section is not straight! By definition, L1 is the length of needle from the blunt/clip end (well, the top of the clip-1 slot) to the place on the needle where the diameter is 2.515mm. That is often called the 'magic number.'

YeeHAw! It's magic!

Where this is critical is when you understand that the steeper the angle of taper the later (farther down) that taper starts! Conversely the slower the angle, the earlier (farther up) it starts.

Aha! Lots of bottom-end response issues with a too-early occurring taper from an 'A' needle, 'eh?

Try the AEQ for sure. You will end up with a plug loading, 4-stroking goober (imo again)..but as long as you have it in hand you might as well get a feel for what works....or not.

Oh...an R1174K translates to a BFQ and a BEL translates to an R1170J

.....if my figuring is correct. Check yourself to be sure.

Cheers!

 

[thegraydog]

re the triple/double taper description -- I actually saw that coming.

Saw and followed links to JD's spreadsheets; trying to digest what you are feeding me for now.

CDave's stuff is what I know about carbs, and to a great extent why I bought the kdx. I printed it out and have read it, oh, fifty times now. With this discussion, and the CDave tutorials, and the keihin needle chart on MXSouth, and my cribsheets of the last two hours, I am beginning to see what I couldn't before. Frustrating? Hey, I'm a remodeling contractor. If you don't give up, everything ends with a snap! :bang:

re the A taper -- you're right, I was picturing it backwards.

re the BFQ and BEL -- I follow that now.

Canyon, I don't know what you get out of this, but it means a lot from my end.

 

[canyncarvr]

Well, there are the thousands of $$ of course........;)

Nah. It's just fun.

I appreciate other riders putting their effort into sorting this stuff out. Those are few and far between, though. Most would prefer simply being told what jetting to use.........and it don't work that way too well.

It is very well worth it to spend the time and the effort it takes to get it straight in your own head. The benefit to you and your bike is a big deal.