Jetting!!! Again and again and again!

[FuriouSly]

Hey there raredesign, most likely air leak at carb boot/reed cage.

Check:
Gasket between reed block to cylinder/reed block to air boot. (if you have a VForce check the modified i.e. hand cut/shaved, surface for incorrect fit to air boot)
Carb boot for cracks/clamp tightness.
Stator side crank seal.

..... you can use an ether/WD40 type aerosol spray and mist near those items above and see if the bikes idle/low RPM is effected (surge/stall).....  can be explosive on the stator area, so use at own risk   

This can definately be old/stock/incorrect reeds.  You can flip the ones over that you have and see if that helps also.  That will put the reed petals that may be slightly flexed outward and weak at high RPM's from age/use more tightly against the cage.

Sly

[raredesign]

Thanks for the suggestions!
Maybe I can post some pics of the carb boot if that is what you call it...going from the air box to the carb is what concerns me.
If you look at the carb, where the boot fits on and clamps...right at the edge of the boot the carb has a lip, or ring on that lip. the left side (carb side) has the boot pulled right up onto that lip ring (unless there is a better name), while the right side goes just before the lip ring. I tried squeezing the air box, and negotiating with it as much as i could, but it just doesn't seem to want to fit right.
The other thing that I am wondering, is that the guy I bought it from, had placed a torque spacer (if that is what it is called) for the reeds. He also used different reeds I think, maybe moose, but not certain.

[raredesign]

I went out yesterday and the strangest thing happend; gas started pouring out of the overflow tubes! I had gone from full tank to half tank in 5 minutes! My buddy and I opened up the carb on the trail, and the float had been set wrong! When all the way up, it was not pushing the stopper all the way (sorry I don't know the technical name for it), so the gas just poured out. We bent it a bit more, start up the bike, and the bike runs like a champ. I was too excited to pay attention to the surging though...not sure. I am just glad that I can ride for more than 10 minutes

[KXcam22]

Rare,
   Welcome to the jetting place.  Take the time to set your float, there are some easy procedures in this thread.  The float level affects jetting so it is important to set it right before you take the time to jet.  I run mine a touch low so I don't lose as much gas from the overflows over rough ground.  As for the surging, mine is likely the worst offender but I rarely notice it.  The only KX500's that don't surge are the ones jetted too rich.  We always joke that as soon as you bike starts to surge you know that your jetting is getting close, but it is very true.  It is easy to adapt your riding style so that you don't chop the throttle as much then it is not an issue.  Hope this helps. Cam.

[kix500]

could somebody give me a good start point to jet for 6000'-8500' ii tried the jetting chart and seems to rich. what is happening is, the bike seems to run ok as long as you are on the gas but if you idle down a tight trail for a couple blocks to a mile the bike will die unless you keep reving it. then when you come to a rock or stump or something and try to blip over it the bike bogs. i have tried a smaller pilot but dosn't seem to have the botom power when it is cleaned out. the bike is a 97 kx 500. with a platnum pipe boysen reeds and milled head.

current jetting is i think.

air 2.5 turns
pilot 55 or 52?
needle stock 82m? can't remember the number but its stock. top clip pos
main is a 165 or 158??
it has been a couple months since i been in the carb, i will go check for sure tomarrow.

srry i daon't have all my info for sure.

thanks
cory

[raredesign]

could somebody give me a good start point to jet for 6000'-8500' ii tried the jetting chart and seems to rich. what is happening is, the bike seems to run ok as long as you are on the gas but if you idle down a tight trail for a couple blocks to a mile the bike will die unless you keep reving it. then when you come to a rock or stump or something and try to blip over it the bike bogs. i have tried a smaller pilot but dosn't seem to have the botom power when it is cleaned out. the bike is a 97 kx 500. with a platnum pipe boysen reeds and milled head.

current jetting is i think.

air 2.5 turns
pilot 55 or 52?
needle stock 82m? can't remember the number but its stock. top clip pos
main is a 165 or 158??
it has been a couple months since i been in the carb, i will go check for sure tomarrow.

srry i daon't have all my info for sure.

thanks
cory

Wow, and that is too rich?...I am running 62 / 175

[kix500]

like i said im lost. i read on here bout guys at sea level -4000' with jetting like 38 pilot and 155 mains, i thought the higher in elivation you go the leaner you should be thats why i am stumped.

thanks

[KXcam22]

KIX500,
  At altitude you will always need leaner jetting, simply less O2 per volume of air.  I think you might be getting confused with Gowens bike which is heavily modified and we ended up going quite a bit leaner to make it run well (and run well it does.....).   At your altitude you will likely need to start with a 50 pilot to get it to idle.  I run 58/165 at 3000-6000 and it is too rich at 6000'.   The needle will be the tough one since the stock N82M is barely ok dropped all the way down.  I would suggest getting the pilot and main about right before messing with the needle.  Here is what I would suggest:

1. Dial the main. Do some plug runs with new cheap plugs. I would suggest starting at 160 and going smaller to 155.  A slight uphill works the best then stop it with the kill button.  If you single track ride like me I tend to run the main a touch lean since I don't spend much time wide open.

2. Set the pilot so you can get a nice idle and the bike pulls clean off the bottom.  I would suggest starting at a 52 or 50.  This is mostly adjusted by riding feel and engine sound.

Make sure you only change one thing at a time.  When it is time to adjust your needle post back and I can give you some more guidance.  You can use the Kawasaki needles or get them cheaper from Sudco.  Hope this helps. Cam.

[Marc S]

I just purchased my 90 KX500 a few weeks ago from the original owner. I have not riden a dirt bike in 20+ years. Since it sat in his garage for the last 4 years I decided to rebuild it. I took it out for the first time yesterday even though it was raining and very muddy. I am in Seattle and the temp was 50 degrees. I went on a 25 mile ride in the woods that was very confined and only got out of 1st gear a couple of times. The bike will not idle very long and had to help it by holding the throttle open in the really tight stuff. When I would get the chance to give it full throttle, it would take a few seconds to clear out, sometimes 1/2 way throught 2nd gear. I then found a 1/2 mile dirt road and ran it through the gears while racing my friends KXF250, I could barely pull him and my KX500 never pulled the front tire off the ground. My bike sounded clean, not loaded up. It starts up within 3 kicks cold or warmed up. The plug is black but I had to idle back to camp. It is very possible that the tire was spinning, it was very wet out. It was still great fun but I belive it has jetting issues. I pulled the carb off today and this is what I found.

Pilot-48
Main-160
N82M needle, second groove from the top
#6 slide

For those of you riding at sea level with cool temps what do you suggest. I would go by the jetting chart but after reading this post it appears to be on the rich side.

[KXcam22]

Marc,
  Congrats on the new bike.  Before starting on the jetting I suggest you should confirm that the compression is within spec.  Low compression will make a bike act like it is running rich, and it will be much slower.  I am assuming that you have set the float level correctly when you rebuilt the carb. Post back when you have confirmed the compression. Cam.

[Marc S]

Cam,
The compression is on the high end of the range, I have not checked the float level yet, I will do that today and get back to you.

[Marc S]

Just finished checking the float level, it is at 17mm. The fuel mixture screw was out 2.5 turns but I have not tried adjusting it. When I start it up cold, I can turn the choke off right away and it will idle on it's own. When it warms up it will idle very low and then die. Sounds rich to me, is the mixture screw on air or a fuel screw? The 160 main sounds lean for sea level, cool weather and the dense air we have in the Seattle area. I did not experience the big hit in power that the rest of you talk about when it comes on the power band. The first ride was just making sure the bike performed well after the engine and suspension rebuild and to give myself some seat time. Now it's time to find somemore power.

Thanks,
Marc

[KXcam22]

Marc,
  Sounds like you know what you are doing.  I run a 165 at 2500' (1992 K5) so your 160 does sound lean.  My favorite procedure is to get your main about right, then find a pilot that will give you a nice idle.  After that you play with the needle but most of the adjustments are based on "feel" and "sound" more than anything.  Then you check the main again to see if its still ok.  I would suggest picking your main from the chart as a starting point then doing a couple of plug runs to verify it.  Might find your lost power.  Your needle sounds about right. Mixture screw is air so more air (screw ccw out) leans the jetting.  Remember to only change one thing at a time.  Also check to make sure your bike has an 8 heat range plug. A colder plug will give you incorrect readings. I have great luck using a BPR8ES.  The projected nose plug runs clean and they are cheap and last.  The BR8EIX is the best plug but has a much higher cost.  If you need to find smaller pilots, KTM's & older CR500s use 38 and smaller. Good Luck. Cam.

[doordie]

Hi guys!

I need some help with my jetneedles to convert them to new standard letters.

1)N89B

2)R1366

What?s difference(leaner/richer) to stock needle N82M?

Thx in advance

Doordie

[jigggawatt]

jetting that works best with my bike. Stock needle second clip, 48 pilot and 165 main , pro circuit 296 sil. fmf pipe,reed spacer, thick head gasket,3800 feet . I could even get away with a 162 main . I like it a little rich. The 296 really chages what jet the bike wants.