Maintenance & Technical > KX500 Original

Surgeing problem

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Paul:
The "8" is the heat range, so yes "7" is hotter than "8"

gowen:

--- Quote from: AFASTboy ---Sup guys, I got a 2000 KX5 thats farily new to me.Ive already done a bunch of cosmetic mods and am know ready for some performance mods.First thing this is with no guestion the fastest thing ive ever rode,ridden, been on in my life.When i first got it it seemed to be jetted really fat,smoked like crazy and spooged out the silencer and all over the inside of the number plate.It seemed to have a funny surgeing problem when i got off the gas from a high rpm run.Thought it was just jetting so i first checked that out im at 1000 feet about 90 degrees and it was jetted with a 178 main which i think was way to big a 58 pilot and clip on the second notch on the needle.It  has a pc pipe and silencer on it since when i bought it ,i mix 40:1  and have since jetted to a 168 main 58 pilot and 3rd position on the needle.I run maxima super M and it runs freaking scary fast now awesome power everywhere bottom all the way to the top plug shows a light tan.The only thing is it surges just a little now not like it did when i first got it but just enough to make me wonder what is going on.It seems that since I dropped the needle clip down to the third position the surgeing  almost stopped but know my bike will barely idle even with the idle screw all the way in.It will idle just fine but i cant raise the idle from where its at no matter what.I run the highest octane available at the pump 92 and Ill probably try some trick fuel that we have around here. It doesnt sound like there is any pinging  or detonating going on just the sounds of the powervalve opening and closing.I think the plugs a BR8ES. Thanks Guys
--- End quote ---


I just recovered from the same issues. http://www.pitbull-racing.com/index.php?name=PNphpBB2&file=viewtopic&t=828

How did I start? Wow, that's tough, first off, I've got a few more mods than normal, alot of research, but found the jetting issues are due to mods richening the mixture, to a serious extreme. I am down to a 45 pilot, 160 main, and the first notch on the stock needle.

I had the same issues with surging, but seemed to cure that by running race fuel (VP C12 or BP 100 Spirits). I'm now testing the VP U4 fuel (when my arm heals I will finish), which has shot my jetting to hell, so no go for U4, but smells sweet. Fuel could cure that. Maybe, one start.

As far as idling, it won't idle cause of too much fuel. I'd start by leaning the pilot one notch, then moving the air screw slowly to find an idle, if no idle is found, then go one step further on the pilot, and repeat, if you are not getting results from the pilot, I'd move the clip on the needle up (2nd notch).

Before my accident I had a perfect running (to me) KX500. Except the U4 made my idle go down, I'm sure cause it is oxyigenated to hell. I hope. :-)

Let us know. Try the jetting first, start from the bottom and go up.

KXcam22:
AFAST,
  Sounds like your on the right track. Keep working on the jetting.  The difference is amazing.  When you get it right all your friends will want to keep borrowing your bike.   My bike is jetted pretty close but I still get a bit of surging at speed on a closed throttle. I put up with it. Gabe is right, on most bikes I set the main first but on the K5 seems to work better starting from the bottom and incrementally working your way to the right main. A good way to start is with the jetting in the chart (here).  A reed spacer and boysens, or a v-force is almost a must. Good luck. Cam.

AFASTboy:
Thanks fellos im going to drop the pilot down a couple steps and give that a shot Ill try that tomorrow and Ill get back with you and post my results.

MIKECALDERA:
Definitely read your plug. mocha brown only! go to leaner mainjet 165,162,160.

one jet at a time, you'll need new plugs for run/chop test then read your plug.

your bike surges at "LOW" SPEEDS?

If so, rebuild time. Wire brush the KIPS.

She will run like a thief in a courtroom afterwards!

I hope I correctly answered and fixed your problem.

Mike

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