Stumble above 1/2

Discussion specific to the 1989 - 1994 (E Series) KDX200 model sold in the USA
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Friedom
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Stumble above 1/2

Post by Friedom »

Hey y'all,
My 92 has been on the back burner for awhile while I've been sorting out suspension. Still sorting it, but I rebuilt the stock forks, put new tires on, rebuilt rear MC, new rear wheel bearings, repacked silencer, flushed carb. It's got a few hours on the full rebuild(replated by millennium, BDK valves, Wiseco piston). Rad valve, stock carb, fmf pipe and stock silencer. Fresh fuel, maxima 2t oil 40:1, high octane fresh fuel. Airbox lid removed, UNI filter. Brand new NGK plug.

Last time I ran it a month or three ago it absolutely hauled on command when the KIPS was open. Was kinda weak until it got on it, and spooged a good bit.
Now it's all nervous and stuttery on top. Can't maintain WOT for anything. Doesn't have that pull that it did.
150mj was what worked best before, tried a 152 and 155 today, didn't make much consistent difference. PJ is a 42 iirc, and brand new needle on center clip. 2800' , 80°.
I'll start doing plug chops, but the 150 is where they landed me last time and the engine hasn't changed.

Ideas? Direction? Suggestion?



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Re: Stumble above 1/2

Post by KDXGarage »

It got hotter and you put larger mains in it??
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Friedom
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Re: Stumble above 1/2

Post by Friedom »

Valid question, but it didn't get hotter. It's rainy season here in the desert so it's immensely more humid and possibly cooler. June was the hottest month on record for us this year.

The humidity though.... that must have an effect?

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John_S
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Re: Stumble above 1/2

Post by John_S »

Jetting in the Florida summer is a pain because of the humidity. What works well at 8:00 in the morning is surely rich at 4:00 in the afternoon following our daily thunderstorm with the sun fully beating down. You could need 1-2 main jet sizes lower when the humidity cranks up. It has a much bigger affect on my bike than temperature does.
Friedom
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Re: Stumble above 1/2

Post by Friedom »

John_S wrote:Jetting in the Florida summer is a pain because of the humidity. What works well at 8:00 in the morning is surely rich at 4:00 in the afternoon following our daily thunderstorm with the sun fully beating down. You could need 1-2 main jet sizes lower when the humidity cranks up. It has a much bigger affect on my bike than temperature does.
Aha, humidity makes it need smaller jets? I wasn't sure what effect it would have if any. Guess I need to pick up some more jets as the 150 I have in there currently is the smallest K main that I have.


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Friedom
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Re: Stumble above 1/2

Post by Friedom »

Problem solved:

Silencer packing got loose since someone was kind enough to remove the mid baffle in my stock exhaust. Thus nothing held the new packing I installed in place so it was clogging the outlet.

The nod goes to ss109 for this one as he helped me track in down in the first 2 messages. Kudos man!

I feel like I finally got to ride my kdx that I've been building for almost 2 years from a 200$ siezed hunk-a-junk. Man, it was worth the wait. No wonder all you people like them, that's a fine set of wheels! Smooth and steady all the way up the line, builds tons of power, stays predictable, always tugging at the reigns. I'm so happy right now!

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Re: Stumble above 1/2

Post by KDXGarage »

I am glad you got it sorted out. :bravo: :boogie:
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