Maintenance & Technical > KX500 Original
Jetting!!! Again and again and again!
Johnniespeed:
KXcam22
The more I learn, I realize how little I know.
John
Good:
OK, venturing into the unknown after studying this whole thread and all the articles in it over and over again, and yes, I understand changing too many things at once may not be good, but I'm going to START with almost everything changed.
My bike runs good down low, but has NO top-end power and I get killed by 250s on the pipe all the time...
I had stock jetting:
168
60
82M in middle position (3rd from short end)
7 slide
1.5 turns out
I think stock reeds, but they look like they are in great shape with minor carbon buildup here or there. It seems like the paint has chipped off the frame a bunch. :| This is the first time I've looked at them, or anything for that matter.
I am at approximately 3000' elevation with 80*+ temperatures as the norm for now, and 110*+ in the summer.
After studying the chart Paul put up, I wanted either a 162 and a 58 or a 160/55 but my local shop didn't have anything bigger than a 50 so i put that in with the 160. I sometimes ride up to Fry Mesa at around 5,000' where the temperatures drop a little and there's a good spot to get wet for a little while before the ride home. :-D
I do have a dented Gnarly pipe, and previous rides up to Fry Mesa have overheated bad. The bike has never idled when warm. It will idle for a minute or two when I first fire it up and it's cold, though. I will START my jetting adventure with the following and tune from there:
160 main (hopefully gain pipe :oops:)
50 pilot
82M in middle position
7 slide
2 turns out
Keeping in mind that I ride on the pipe, what do you guys think of starting here? Any and all suggestions are welcome! :mrgreen:
Can anyone explain how to do a plug chop? I don't follow that article well... I don't know what it means by, "chop the throttle." Reading the plug seems difficult also, but I'm gonna give it a shot.
KXcam22:
Good,
With the stock jetting your bike must have been very rich at altiude. I ran 55/165 at 3000-6000 and it was too rich on top at 6000' but nice at 3000'. The needle will be the tough one since the stock N82M is barely ok dropped all the way down (clip in the highest slot). Your temps are higher than mine so the 50, although lean, may work ok. Make sure you watch for "lean idle runaway". That is where temp/altitude/humidity changes to get your bike more air and the idle begins to run away by itself as the mixture gets too lean. With the 55 I experienced that when ridiing in snow. I would suggest eventually trying a leaner needle like the N82R. It is a kawaski option number, although sudco might have a cross for for it. Get the main and pilot right first. KTM dealers are good sources for jets since the 300 uses the same carb. Also the CR500. A Plug chop is a technique to get a clean reading of jetting on a new plug. Essentially you ride up a mild hill (for engine load) at the throttle setting you want to check, (generally 1/4 1/2 3/4 WFO - putting tape around the grip with arrows helps) use the killbutton to stop the engine, and immediately remove the plug. Put a crap plug in and ride to the bottom. Put in another new plug and do it again etc. Use cheap BR8ES plugs since they give the same reading as expensive ones. Your KX will be a different machine after this, smooth and wonderful. If you are overheating try buidling a rad overflow bottle. easy and effective. Hope this helps. Cam.
jfabmotorsports.com:
The main jet in the Keihin FCR's on the kx450f is also the same main as the PWK. The stock kx450f comes with a 175. Also for those hard to reach places....Ebay.
http://cgi.ebay.com/ebaymotors/175-Hex-Main-Jet-Genuine-Keihin-Brand-for-FCR-and-More_W0QQcmdZViewItemQQ_trksidZp3286Q2em20Q2el1116QQhashZitem110248411478QQitemZ110248411478QQptZSnowmobileQ5fPartsQ5fAccessories
JFAB
Good:
Thanx guys, so you think I should start with the needle in the highest, or top slot? If I can get away from work while there's still light, I'm going to put the carb back on today and might chop a few plugs.
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