Surgeing problem

[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

[Paul]

Try a BR7ES, middle clip, 170 main, 2 turns on the air screw. Make sure the carb boot is in good shape and has a good seal on the reed block AND - most messed up by everyone - make sure the seal between the carb and the boot is not over-tightened. If it is it will suck a little air and surge slightly. ALSO, put some RTV red around the pipe flange on the head so it gets a good leak proof seal.

Let us know what you end up with.

[AFASTboy]

Thanks man Ill give that a shot could it be caused by that plug? Is the one im useing maybe to hot?I now my exhaust flange seems to be seaping just a tad but not really at all since leaning it out with the 168 jet.I tried going back to the second clip position but the surgeing got worse.The condition doesn't bother me but I was just wondering if this is pretty common and why it does this.Havent tried the 2 turns on the airscrew yet might make it better thanks.

[AFASTboy]

is a BR&ES colder than the BR5?

[AFASTboy]

Sorry I mean the BR8 not the BR5

[Paul]

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

[gowen]

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

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

[AFASTboy]

It doesnt surge at low speeds it just surges when you let off the throttle from running it up at high rpm, plug reads perfect light brown Im sure it has to do with jetting probably to rich on my pilot because my idle is not effected by my idle screw and i thinks its getting to much fuel on bottom causing the surgeing.Went and got a smaller one took it home removed carb and old pilot jet and tried to screw in new and they must have given me the wrong style,wasted time again.Going to get the right one today.Ill let you know about the results

[MIKECALDERA]

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It doesn't surge at low speeds it just surges when you let off the throttle from running it up at high rpm

Yeap, I'll take your bets its the KIPS by your exhaust sticking from carbon.

Unfortunately, you ran a very rich main jet which you can put the blame on. If you ever fouled just one PLUG that should be a warning.

No Problem: I rebuilt my 02 500 three times already until I dropped a 162 main from 168. BIG Difference in Power and crisp throttle. And most importantly, NO(less) BLACK SPOOGE.


If you hold the throttle wide open no problem. It's only when you let off the throttle she starts to rev up than down.

Take 2 asprin and call me in the morning. IT"S KIPS BROTHER KIPS.

  Mike

[kawdude]

Do a search on this topic.  Lot's of posts and lots of opinions.  When I increase the main it gets worse.  However the adjustment of the problem seems to be in the pilot jet or the air jet.  A wore out slide could also cause the problem.  Oh ready Gowen's sticky post.  It's the longest god d**n thing I have ever seen.

[AFASTboy]

Lowered my pilot jet to a 52  and man does it kick ass know it idles know and I can controll it with the idle screw and from a full speed run it comes down to idle perfectly smooth.Starts with two(good)kicks and just launches with the crack of the throttle.Im going to move my needle clip up from the third groove that its at now and see if that gives a little more in the midrange even though it seems perfect right now . Thanks for all the help guys and thank god it wasn't the powervalve,you had me scared as i was looking for a easy fix and it really was.

[gowen]

52 pilot  . I'm stuck on a 42   .  Can't get much of an idle and still feels slightly rich. Assuming a port job is to blame, I'm unsure as my KIPS are perfect in operation. But, kawdude is right, the pilot is usally to blame on the KX.

Glad you are finally getting it done.