Needle Confusion..

[OLHILLBILLY]

I've read several of the needle posts, and the more I read the more confused I become.
Simplified.. I have a stock '04 200 with the airbox cover removed. Jetted 40 primary, airscrew 2 turns out at 1000/1200 ft altitude, needle clip in second notch from the top, 152 main (not done any plug chops yet, but figure still a little fat due to the amount of smoke on top).

Everything "seems" good now, but am planing on adding a Pro Circuit Platinum 2 pipe and a different reed block (Boyseen or Vortec).
Question is.. Do I need a diferent needle, or can I raise the stock one enough to work? If I need a different needle, which one and how do I read the letter codes ?
Understand the primary/airscrew and (plug chop reading) main jet part, but the intermediate needle still baffles me.

[80elkster]

Read the info at this link specifically "Understanding Jet Needles" then order yourself DEK and CEK needles from Sudco.
http://justkdx.dirtrider.net/jetneedles.html

[OLHILLBILLY]

Read the info at this link specifically "Understanding Jet Needles" then order yourself DEK and CEK needles from Sudco.
http://justkdx.dirtrider.net/jetneedles.html

Thank you! I'll study the article for a while and see if I can figure out what I'm doing.
I'm thinking I'm alright now except for a slight rich condition on the main circuit, but when I rebuild the top end and mod it will be when I'll have to change stuff again to try to get it spot on.

[canyncarvr]

Re: 'Question is.. Do I need a diferent needle...'


"Need' is subjective. When it comes to needles, it's more a 'choice' than a need.

The needle is generally considered to be where a lot of the 'personality' of your bike comes from. The main, pilot, and needle jets are all physically fixed..they don't change size with throttle position. The needle does change, of course...and you're the one holding onto the other end!

You didn't mention which needle you are using. The OEM needle I presume?

I looked up some comments from James Dean about the OEM needle:

It is the stock jetting that is odd!

I will go out on a limb and speculate that Kawasaki thought this would be a sweet play bike and need very clean jetting. So they put a lean straight diameter (2.725, or 2.735) , a lean taper (1.25 degrees) , and a lean clip position (L1=39.95) and then came up with 1172N or 1173N. The higher taper start is throwing you guys off track by being lean then rich then lean in an extreme and (to date) unexplained way.

I have the write-up on jetting an RB-Designs carb that JD contributed much to. If you're interested in reading about needles, what they do and where, I'll be more'n happy to send it to you if you want to take a look-see.

JD's jetting guide is an EXCELLENT resource. It's easy to see on a graph what a needle change will accomplish.

You're familiar with his spreadsheet? Well worth it, imo.

You can bench test jetting changes on your 'puter!





...let me know if you're interested in reading that .doc. It's only 60-some pages....

[OLHILLBILLY]

Yes, I'm using the stock needle in the second notch from the top (lowered it one notch when I re-jetted). Bike has good bottom end and a pretty snappy hit around 1/4 to 1/3 throttle so I figure I'm pretty close now.
I'll go take another look at JD's spreadsheet for the KDX. I see he's showing the same jetting I'm using for hie example so that ought to be helpful.
And yes, I'd like to have a look at the RB carb write up. 60 pages, it'll take me a while to read through but I'm sure will be interesting. I'll PM you my email addy.
Everything seems to be in line with my intake so I'm going to leave it as is for the moment and move on to the suspension next.
But toward the winter I'm wanting to do some motor modding so I'll be back in the carburator again. Collecting all the info I can now so I have a plan then.
Thanks for your help, I need all I can get.
Tom