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2004 KX 250 loading up when on the line

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My bike keeps loading up when waiting at the gates? I don't let it sit idling long, start it about a minute or two before the gate drops.  I'll hold it WOT in attempt to clear it up, but that doesnt help much, blows out a ton of smoke, it seems fine once I get to the first turn.  Went through two plugs this weekend, both were pretty black.  I am mixing at 32:1 with amsoil.  Stock jetting.  I'm don't putt around so I don't think that's the problem,  B class rider.  I am going to pick up some smaller main jets tomorrow.  Anyone have any good starting points for jetting?  Typically in the 70s when I'm racing.  Any help would be appreciated!

 

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My bike keeps loading up when waiting at the gates? I don't let it sit idling long, start it about a minute or two before the gate drops. I'll hold it WOT in attempt to clear it up, but that doesnt help much, blows out a ton of smoke, it seems fine once I get to the first turn. Went through two plugs this weekend, both were pretty black. I am mixing at 32:1 with amsoil. Stock jetting. I'm don't putt around so I don't think that's the problem, B class rider. I am going to pick up some smaller main jets tomorrow. Anyone have any good starting points for jetting? Typically in the 70s when I'm racing. Any help would be appreciated!

Start with pilot jet, controls idle - 1/4 throttle. Adjust your airscrew so you get the best idle/throttle response. If the screw is turned out more than 2 and a half turns go smaller on the pilot if it is at less than half a turn go bigger. The needle controls the biggest range of throttle , from 1/4-3/4 throttle. Adjust clip up (moving needle down) to make it leaner , move clip down to make it richer. Main jet is from 3/4 to full throttle. A good way to check this is a plug chop test

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To do a plug chop test you start the bike up and warm it up properly with an old plug. Then once it's warmed up out a new plug in. Find a long straightaway and get into 4th -5th gear hold it wide open for about 4 seconds then pull in the clutch and hit the kill switch coasting to a stop. This initially takes a snap shot of the plug and how the main jet is. Cut a small portion of the threads off and see how the colors look. You can read up more on that. All this stuff I just told you I have learned from TT. There are many people on here that will teach you a lot. Cheers. Goodluck

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My bike keeps loading up when waiting at the gates? I don't let it sit idling long, start it about a minute or two before the gate drops. I'll hold it WOT in attempt to clear it up, but that doesnt help much, blows out a ton of smoke, it seems fine once I get to the first turn. Went through two plugs this weekend, both were pretty black. I am mixing at 32:1 with amsoil. Stock jetting. I'm don't putt around so I don't think that's the problem, B class rider. I am going to pick up some smaller main jets tomorrow. Anyone have any good starting points for jetting? Typically in the 70s when I'm racing. Any help would be appreciated!

Had similar problem on my 03 kx 250. Fought it for a while. Found the spring in the float needle was broken. Somethin to check out while it's apart. Hope you get it!

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Elevation is quite important.  If you have not rejetted from stock and you are above sea level you have some work to do.  I'm running way leaner than stock in my 03 KX250.  Main is a 148, needle clip is all the way at the top and I think I'm running either a 42 or a 45 pilot with the air screw at 2.5 out.  This works great at 5500 feet.  Crispest jetting you have ever seen.

 

Seems like a lot of people don't understand the importance of jetting.  Running rich enough to foul plugs is like walking around with your shoes untied.  These things run so much better when they are jetted clean. 

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Forgot to mention my trans oil is disappearing.  My Dad thinks there is a void in the sealant in the center case and it is bleeding through into the crank and burning up, causing all of the white smoke.  Sound possible?  

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Forgot to mention my trans oil is disappearing. My Dad thinks there is a void in the sealant in the center case and it is bleeding through into the crank and burning up, causing all of the white smoke. Sound possible?

oh yes , sounds like a right crank seal. Not to big of a job just be careful of the bearing behind the seal. Goodluck!

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oh yes , sounds like a right crank seal. Not to big of a job just be careful of the bearing behind the seal. Goodluck!

Has new crank seals/bearings, only about 2 weeks old  :excuseme: Pulling the motor tonight to open it up

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Has new crank seals/bearings, only about 2 weeks old :excuseme: Pulling the motor tonight to open it up

I couldn't see oil getting there anywhere else but that seal. But goodluck

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Crank seal is actually a huge job.  Got to split the cases and pound the crank bearing out.  It is not accessible from the outside.

 

What kind of crank did you use?

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Crank seal is actually a huge job.  Got to split the cases and pound the crank bearing out.  It is not accessible from the outside.

 

What kind of crank did you use?

Not too bad, have split cases quite a few times.  And it's the stock crank, measured run out and it is still within spec, wasn't close to  service limit. 

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Crank seal is actually a huge job. Got to split the cases and pound the crank bearing out. It is not accessible from the outside.

What kind of crank did you use?

Oh didnt know that on the kawis. On the ktms all you have to do is take the right case off, clutch, and primary drive gear and just pull seal out, and pound the new one in. Seems like he has done this before so shouldn't be a big issue for him

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JUST MY 2CENTS, BUT I DONT LIKE THE 32:1 MIX...

RUN MY 94 HARD FOR YEARS AT 50:1

 

BUT 32:1 IS OK IF JETTED FOR 32:1...

THEN NEVER STRAY FROM 32:1....

 

REMENBER INCREASING MIX RATIO ( I.E. GOING FROM 50:1 TO 32:1)LEANS THE BURN

AND DECREASING WILL ENRICH THE BURN.

 

MAN, I MISS THAT BIKE !!!

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