KX Riders

Maintenance & Technical => KX500 Original => Topic started by: martinfan30 on January 26, 2009, 05:16:22 AM

Title: Jetting and altitude change
Post by: martinfan30 on January 26, 2009, 05:16:22 AM
I've seen the  jetting chart and have a question. For my elevation (4500 ft.), It says I need a 160 main. For when I go down to CA. and ride near the Husky Memorial (1500 ft-2000 ft) should I rejet when I get there?

Also, what jetting is stock?
Title: Re: Jetting and altitude change
Post by: Friar-Tuck on January 26, 2009, 08:23:01 AM
clymer M447-2   pg.336

2000-On
PWK 39  168 Main  58 Pilot  #7 Slide cut-away  N82M Needle   Air screw 2 turns out   15-17mm float height

There was no clip position in the book, the '99 is the same needle it is 3rd clip position

 We ride from 3500-6000 ft.   I know every bike is different, our kx 500's have a pc pipe, I have rad valve his is stock reed.  Mike and I are happy with this, #7 slide, 2nd needle clip (n82m) a 158 Main #55 pilot and 11\2 (or so) air screw.   
  Mike puts a larger main (170) in when he goes to Oregon dunes , and lowers clip, how far depends on weather.
  I run Blue Marble 50:1  ngk heat range 7   Mike runs Maxima 927 40:1   ngk heat range 8  (he rides alot harder than I do)
  Tuck\o/
Title: Re: Jetting and altitude change
Post by: Bigtim on September 23, 2009, 12:32:27 PM
i've had trouble opening the jetting chart link. any body running at around 10,000 ft?
Title: Re: Jetting and altitude change
Post by: BullKaw on September 23, 2009, 12:43:37 PM
Birds don't even like it that high let alone a Kaw.  :-P
Title: Re: Jetting and altitude change
Post by: Bigtim on September 23, 2009, 12:49:55 PM
i've only been here 3 days and am winded by just a flight of stairs. im in good shappe at sea level. here its a whole different story.
Title: Re: Jetting and altitude change
Post by: Johnniespeed on September 23, 2009, 01:25:12 PM
Bigtim, I am from Michigan ( about 765 ft above sea level ) and when I go to Colorado to ski, I too get winded from only a flight of stairs, but after about five days that goes away. Lots of water helps some. Never tried rejetting at that altitude yet.
 John
What is the altitude where you are ?
Title: Re: Jetting and altitude change
Post by: Atrain on September 24, 2009, 03:31:40 AM
Bigtim. I'm at 8600ft and go up from there. I run a 150 main and 40 pilot. I have the clip in the first position and the air screw at 2 1/2. FMF Gnarly pipe.
Title: Re: Jetting and altitude change
Post by: barryadam on September 24, 2009, 05:04:49 AM
I think I'm at 165 now on my main.
I've only noticed jetting issues when I run WFO for extended runs on El Mirage (el 2840).
SBNF, Los Padres, etc. are higher elevations, but never a problem because they are not WFO riding.  Even Johnson Valley (Soggy Dry Lake, Sunfair Dry lake), has not been a problem as they are not nearly as looonnnnggg of a WFO run as EM.
So unless you are blazing to the Husky at full speed for extended time, I wouldn't worry about the main.  You are more likely to be running on the pilot jet which seems to me to be less sensitive.  What pilot jet are you running?

How did you get a 160 for 4500 feet off the jetting chart?
Title: Re: Jetting and altitude change
Post by: jfabmotorsports.com on September 24, 2009, 06:02:04 AM
Crean and oil the filter properly, put in a good used plug, find a nice stretch of road, run it full throtle for 5-10 sec and kill it clean. Clean means do not let it idle. WOT push the kill button and clutch it all at the same time.
    Now go read the plug.

  The main jet on a carburetor is not there for those long extended runs. If you are in the main circuit for a micro sec then the air fuel ratio needs be right, as with the other circuits.
Title: Re: Jetting and altitude change
Post by: 95formula847 on September 27, 2009, 08:46:42 AM
Crean and oil the filter properly, put in a good used plug, find a nice stretch of road, run it full throtle for 5-10 sec and kill it clean. Clean means do not let it idle. WOT push the kill button and clutch it all at the same time.
    Now go read the plug.

  The main jet on a carburetor is not there for those long extended runs. If you are in the main circuit for a micro sec then the air fuel ratio needs be right, as with the other circuits.

I dont wanna change the subject but quick question. Since the method you just explained is for the main jet and clip... could you lug a bike around and do the same to get your pilot jet? Im a noob to all of this.
Title: Re: Jetting and altitude change
Post by: Bigtim on September 30, 2009, 07:36:23 AM
i took out 165 main and 55 pilot from sea level, and now at 10,000 ft it seems to be running good with158 main, 48 pilot. running good according to plug reading. i havent had the chance to actually go for a ride yet. needle still at 3rd clip. the chart said to use a 55 pilot, but i only had a 48 and thats what i ran in the bike in Montana( were shes from) from 6500 to 9000 ft.