playing the jetting game

Joined
Oct 29, 1999
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#1
after a bunch of test and tune i think im where i want to be jetted, im pretty pleased with the results i may even be a bit rich but id rather have the confiadance to be able to run hard at WOT with out the worry of running lean, it seems funny but with all the mods on my bike it seem that everyone here is running way leaner setup than i am?, im on a 97 kdx 200 with a fmf torque pipe and silencer, open air box and power reeds, at 2,100 ft elev. and about 70 degrees, im running a 45 pilot and a 155 main, needle jet clip in the bottom position and the air screw out 11/4 , the bike starts right up on cold start, and runs strong throuhout, which is kinda odd because of the setup that was in the bike was 45, and 158, needle in the top clip, air screw out 11/2 the bike ran good but was a bear to get started when cold, from what i can understand this is only a bit leaner than my previous setup but it made a world of diffrance in the cold start department, what i cant understand is that some of you are running a 152 at mid clip? man with a plugchop that reads way lean on my bike, maybe im just scared about burning a piston, does this sound right?, its running better, one thing about this carb jetting stuff im getting real good and tearing this carb apart and putting it back together in the field, just wanna get this all straight before the good riding season is here.

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jaguar

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#2
man, if you really know the difference between lean and rich then Just Do It and trust yourself. It don't matter what other bikes like, it matters what makes your bike run the best.
:-)

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KIPS repair from manual: http://www.ioa.com/~dragonfly/moto/kips.html
my sweetheart: '89 KDX200 SR
 
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Jan 6, 2001
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#3
You went the same direction as myself. Pipe, airbox and ended up down one jump on the main, pilot, and dropped the needle one click.

I never messed with my airscrew because it always idled fine, both before and after.

Mine is still not "light" brown, but more of a creamed coffee. I'd rather have it there than too lean and it's better than pitch black, which is where I started.

The pilot helped me on the bottom end, ripping at 1/4 throttle in the woods and it wouldn't pull top gear before I started.

Much better.
 

Sage

dirtbike riding roadracer
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Mar 28, 2001
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#4
You may have less compression than most people that your getting your jetting specs from, this will give you a weaker intake pulse and thus a bigger jet or you may have a air leak? only your bike knows what jet it wants and if your plug say's it's jetted right then so be it.

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Sage Wilkinson, KDX Link 1
 
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Oct 29, 1999
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#5
thanks guys thats what i figured, im trusting my own mechanical skills, just wondered if anyone else was running close to this setup, im taking C-daves advise and running a bit richer, i guess you just to hit a happy medium.

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Joined
Oct 14, 1999
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#6
In this thread a reference to 'hard starting' and air screws and how their adjustment relates to idling 'good':

Keep in mind that the idle speed method of adjustment for the AS is just the start. Throttle reponse (quick wrist flicks to about 1/4 throttle) is where the AS is fine tuned.

Also, a turn on the AS of 1/16 turn can make a pretty big difference in both the response AND starting the bike.

My bike would have to be kicked silly to start it hot. AS in 1/8 fixed that scenario..AND improved the throttle response to boot.

Note: I have the RB carb mod which makes the AS act a bit finicky. Still, the response/start issues were B4 that mod was done.

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  • OLD member
    'oh-oh' KDX 200
    '86 Nighthawk 700 SC
    (a motorcyle even if it doesn't have a chain!)
 
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Nov 24, 1999
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#7
If you 're happy with the jetting stick with it. I have a 97 KDX 220 and the jetting was great for that bike. Then I put the same carb on my 2001 KDX 220 and it ran boggy. So I dropped the clip and went from a 42 to a 45 pilot jet. Now I'm happy again! By the way 2100 feet, are you riding in Somerset. That just seems high for Pittsburgh.

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#8
i ride near seven springs and even near mt davis, "highest point in PA. 3,200" then i also ride at hillsville im pretty sure its about 1,000 ft elev, thats one thing about living in PA the major elevation changes and our wild tempature changes play havoc!, im hoping to get a mini KDX spode for the PA and Ohio riders at hillsville this summer when the weather gets better.

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