Does the pilot jet affect the plug reading at WOT

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motofox2006
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Does the pilot jet affect the plug reading at WOT

Post by motofox2006 »

Im running a 52 pilot on my 91 kdx at the moment and thinking of changing it to a 45, by doing this I wont be leaning the bike out majorly so that it damages something would I. Does the pilot affect the plug reading at WOT.

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Post by 2001kdx »

No, That is a safe pilot, but don't jump down 2 sizes.
Do a search here about jetting, check out inda's jetting guide, and go to just kdx on dirtrider, they have almost unlimited info.
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Post by canyncarvr »

The sort of problems/symptoms you may have with a too-lean pilot:

1. It will be hard to start in choke/cold situations.

2. When it DOES start in a choke/cold situation, the engine may want to rev quite high. That situation can be modulated with the kill switch.

3. A too lean pilot will make it impossible for the air screw to have any worthwhile effect.

4. Throttle response will be poor.

5. Transition from the slide/pilot/airscrew range of throttle to other ranges will be notchy/unsmooth/harsh.

But, no. You won't be risking seizure or major engine damage running at WOT.

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Post by motofox2006 »

Hi, in one of my other posts you said for me to go straight to 1 155 from a 158 and from a 52 to 45, why you change your mind, and by safe do you mean that the pilot does not affect overall mixture rich/lean at WOT.
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Post by 2001kdx »

I said that because it was a general starting point. I didn't realize you were way up at a 52. The stock 48 pilot is a bit rich for me at sea level during 35 degree farenheit temps.

The pilot will effect WOT, or so I believe. CC is the one to ask here, he is the man.
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Post by motofox2006 »

fredette recommends a 45-48 pilot jet for my bike so is the 52 right or is fredette right should I keep my 52, to me the 52 seems rather rich in comparisson to what people recommend. Ive also heard of people getting better throttle response when changing to a leaner pilot. Also if I change my1172n needle in second clip from top to a 1173n in middle clip is this a good idea because that is what fredette recommends. Thanks
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Post by motofox2006 »

Im basically at sea level most of the time about 1000 metres at highest point and in winter the temp is about 55 fahrenheit and in summer about 70 do you still think my pilot is alright
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Post by canyncarvr »

I indeed am the man!

But...only 'cuz people look at me funny when, as old as I am, I try to pass myself off as a boy. :wink:

I looked up a '91 KDX 200 on BuyKaw. A 52 pilot is NOT what the bike came with. A 48 is.

Why are you two jet sizes bigger than OEM to start with?

...I think this horn has been 'rounded' before. Hasn't this been discussed already?


In regard to your needle question: You would be leaning the lower throttle range just a tad with a larger diameter, but enrichening the middle throttle range due to starting the taper sooner (raising the needle). Same thing said another way, you will be more lean 0-1/8 throttle and more rich 1/8-7/8 throttle.

I'd guess the chances of that change making much of a difference..any that you could tell..are slim.

If you're changing needles, make a change that makes a difference. Bounce this off m0rie, but the '91 jetblock is a different height (I think) than the 'H' models.. so something like a CGK with the OEM slide, WHICH by the way, happens to be a #6.

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Post by motofox2006 »

So you think I should keep the 1172n and put it on what clip.
The reason I have a pilot 2 sizes richer than stock is because I bought the bike second hand just over 1 year ago and for some odd reason he was running it on that jet. What are you thinking in terms of jetting for me.
By the way what to do you mean #6

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Post by m0rie »

89-94 KDX PWK's are indeed a little bit different from the 95+ KDX PWK's that followed. Besides the afore mentioned jetblock height (2mm lower in the 89-94 PWK's) the throttle slide is also a different design (like the airstryker carb slides) and a #6 cut as noted by CC. The upshot is that the two generations need a different needle and jet set to be happy. The OEM needles (and stock jetting) are less than useful IMHO and should be replaced with an aftermarket needle and the appropriate jetting. For the 89-94 KDX's that would a CGK in the #1 or #2 clip position. A 95+ (35mm/KDX 200 stock) would benefit from a CEL in the #3 or #4 clip position. Both generations would have a good starting point with a 42 pilot and a 152 main with 2 jet sizes on either side for good measure in tuning.
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Post by m0rie »

A stock KDX with stock jetting is already pig rich. With a 52 pilot your not going to be getting an accurate reading a WOT. I'd drop the pilot back down to a 48 if your going to keep the stock needle (put it in the #4 clip). The #6 refers to the cut of the throttle slide. The higher the number, the steeper the cut and the leaner the slide makes part throttle. The stock H series slide (95+) is a #5 btw.
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Post by m0rie »

Once again another thread is killed by my posting in it! :lol:
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Post by canyncarvr »

You din't kill nuthin' ...just answered all the questions!! Gave the final word!!

Hence: 'Bounce this off m0rie.....'

Thanks!

(I'd posted more junk to this thread..immediately followed by a fatal attraction error and a memory.dmp. Didn't bother doing it all over.)


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Post by motofox2006 »

Sorry about the length...

One more question, I bought a 45 pilot from the kawasaki dealer today and put it in my bike. My jetting is now a 45 pilot with a 158 main and the needle set 2 clips from top. I started my bike up with the new pilot in it and turned the air screw out, I counted how many turns till its fastest idle and it was 2. Considering I went from a 52 to a 45 the air screw still seems to far out. After starting it and running it I took my plug out and had a look at it (I dont know if this is remotely useful as it was not a plug chop) the plug indicated me running rich it was black. Do you think I should go even leaner in the jetting, that would be going against what fredette recommends. Do you think I should ride it first to make sure it is at normal operating temperature or maybe I should raise the needle clip (lower the needle). Im not an expert in jetting would appreciate some suggestions thanks.

Also m0rie why do you say put the needle in the #4 clip as wouldn't that richen things up.
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Post by KDXer »

Fourth clip is one from the top or blunt end of the needle. If your on 3rd raising the clip one will lower the needle making it leaner as in less gasoline.... Cappish ?? :mrgreen:
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Post by canyncarvr »

Mr. Crikey wrote:Fourth clip is one from the top or blunt end of the needle. If your on 3rd raising the clip one will lower the needle making it leaner as in less gasoline.... Cappish ??

Yanno...Mr. Crikey...when you're completely off base and FOS...most of us can't tell whether you know it or not.

Mr. Moto might actually believe what you are telling him..and that would, of course, be wrong.

moto: Mr. Crikey is bass ackwards. You could say he's upside down..and you would be correct seeing as he IS upside down. Clip numbers START at the blunt end. Clip #1 is most lean on a particular needle, #5 is more rich because the needle is raised OUT of the needle JET farther.

Ho Ho Ho...what a funny, Mr. Crikey! :butthead:

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Don't set the air screw at the highest idle point, but the best throttle response point. This is likely going to be IN from the high idle spot. IF high idle is at 2-out you're pretty close.

Yes, #4 is more rich than #2. The pilot and needle work in different throttle positions, though. So, it is not at odds to say 'lean the pilot, richen the needle.' Again...the best thing to do is try it. Changing the needle clip will take you a couple of minutes..so change it!

That you end up different from someone else's recommendation should not be surprising. Fredette's recommendation was not meant to be taken as gospel, but a close guess. Your bike may be different.

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Post by motofox2006 »

Ok thanks for all the advice might give the forums a rest for a while and fiddle with my jetting myself, thankyou everyone
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