KX Riders
Maintenance & Technical => KX500 Original => Topic started by: bige on November 30, 2011, 11:07:08 AM
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im really confused on my jetting situation,heres the deal 2003 kx 500 all stock even the brass, compression good with fresh top end, reeds, etc. mix fuel 93 octane klotz 32:1, elevation 2000ft, air temp 60deg. stock jetting is real rich so i droped main jet to a 165, pilot a 55, and needle clip to #2, air screw 2 turns out. bike ran cleaner but still had some studdering at 1/8 to 1/4 throttle, looked at porcilian of plug at base, had black ring half way up then rest was dark brown, so i leaned it out more. main 162, pilot 52, needle same clip #2 and airscrew 1.5 now my plug is still black half way up porcilian but rest way up is off white, from every thing i read there should be a brown ring a few millimeters up from base no black, my question is should i go to a 160 main? but every jetting chart i see from pro circuit to team greens all are at or close to stock jetting. i want max power but in order to get my plug to read right i need to lean it out beyound my comfort zone. should i go by the base of plug color or keep jetting to rich with what i got.
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what heat range plug you running? and what plug for that matter... :wink:
32:1 is a bit heavy on oil (in my oppinion.... dont want to turn this into a Oil war like so many a thread has gone to)
Welcome to the site BTW..
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x2 heavy on oil.
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br8es
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br8es
#1.. buy a better plug... K5 likes the gold paladium and iridium style plugs (reason it calls for em in the manual)
#2 drop the oil back to 36-40:1 (I run 40:1) which is what Id reccomend... especially on Klotz Super tech...
go back to your 165 55 jetting and see what it does...
as it sounded like you were close there..
the Black ring can be a combo of s**tty plug, too much oil... and perhapse you may need to jump a heat range...
but dont jump a heat range till you change the first two issues...
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when i leaned it out it puled a little harder but that low throttle studdering stinks im afraid to lean pilot below a55. by the way whats up with the surging when off the throttle? at mid rpms. this is my first kx 500 and love it but these issues are getting anoying
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HAHA....try screwing your idle all the way in,that should stop the majority of the surging.
I do agree with Motorrad...go back to your original jetting,and try the 40:1...I run that as well with excellent results,and if all else fails,try a hotter plug and see if that changes anything.
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shouldnt surge at mid RPM... pick the needle back up to #3
where are you located anyways>?
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thanks for the replies, ive always ran the br8es plugs yz 250, rm 250 i guess ill try those plugs at a 7 range and see. but was wondering would a mix ratio of 50:1 be a bad thing and run to rich?
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thanks for the replies, ive always ran the br8es plugs yz 250, rm 250 i guess ill try those plugs at a 7 range and see. but was wondering would a mix ratio of 50:1 be a bad thing and run to rich?
Id try the good plug and 40:1 before you go messing with heat ranges... changing a heat range at this point will throw you off... if your bone stock, you should end up at a #8 heat range plug... K5 like em there.
also go back to the 165 55 when you do so... Mid range surge is BAD JU JU... I have seen way more bikes STICK due to a lean mid range than anything else... Roll off the main to the Mid and STICK...
at minimum pick the needle back up to #3 to cure mid range
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im in wv, i thought of moving clip back to #3 and see but it ran cleaner and less studdering at #2. i figured the surging off throttle was a lean condition on the pilot but that 58 is way to rich. my idle is set at the lowest and even took all idle out and it still surges a little but not as bad as when idiling
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oh... when your tuned CLOSE the idle will run on a few times (surge) but not mid range.
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only surges going down hills with throttle closed will surge and buck at a mid rpm with closrd throttle. upon giving throttle just studders at 1/4 opening but runs crisp all way to full throttle
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i did ride a 97 cr 500 before and it did that off throttle surging to. is this a 500 only issue?
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Every 500 I ever rode surged....the real Ping King was the ole YZ490's.I read a post on here several months ago that said to turn the idle screw all the way in,and that would stop it from surging...I did'nt really believe it,but I tried it,and it helped ALOT.
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try next size hotter...7
You should NOT band-aid a ill running KX500 with a "hotter" #7 plug. Get to the true root cause and correct.
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im really confused on my jetting situation,heres the deal 2003 kx 500 all stock even the brass, compression good with fresh top end, reeds, etc. mix fuel 93 octane klotz 32:1, elevation 2000ft, air temp 60deg. stock jetting is real rich so i droped main jet to a 165, pilot a 55, and needle clip to #2, air screw 2 turns out. bike ran cleaner but still had some studdering at 1/8 to 1/4 throttle, looked at porcilian of plug at base, had black ring half way up then rest was dark brown, so i leaned it out more. main 162, pilot 52, needle same clip #2 and airscrew 1.5 now my plug is still black half way up porcilian but rest way up is off white, from every thing i read there should be a brown ring a few millimeters up from base no black, my question is should i go to a 160 main? but every jetting chart i see from pro circuit to team greens all are at or close to stock jetting. i want max power but in order to get my plug to read right i need to lean it out beyound my comfort zone. should i go by the base of plug color or keep jetting to rich with what i got.
OK, i'm going to ask the question again that I always ask when someone describes your engine symptoms... what exactly is "good compression" is this just a guess or have you done a real compression test with a guage ?
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compression is at 150 tested with a guage. i can deal with the surging somewhat just trying to get used to it but i want to get that 1/4 throttle response cleared up and stop running choppy and studdery but im afraid of going leaner than a 55 on pilot jet, with that jet i get the fastest idle at 1.5 turns out on air screw. jetting this bike is a real pain thats why ive been studying on plug color and how to read one correctly thats where the mixing ring is supposed to be at the base of porcilian and brown not black but if i go by that then i would be at a 160main,52pilot with needle in the #2 clip posisition and air screw 1.5-2.0 that is crazy lean to me. but someone said that it doesnt matter if the whole porcilian is white as long as there is a 2 millimeter brown mix ring at the base. has any body jetted their bike this way?
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compression is at 150 tested with a guage. i can deal with the surging somewhat just trying to get used to it but i want to get that 1/4 throttle response cleared up and stop running choppy and studdery but im afraid of going leaner than a 55 on pilot jet, with that jet i get the fastest idle at 1.5 turns out on air screw. jetting this bike is a real pain thats why ive been studying on plug color and how to read one correctly thats where the mixing ring is supposed to be at the base of porcilian and brown not black but if i go by that then i would be at a 160main,52pilot with needle in the #2 clip posisition and air screw 1.5-2.0 that is crazy lean to me. but someone said that it doesnt matter if the whole porcilian is white as long as there is a 2 millimeter brown mix ring at the base. has any body jetted their bike this way?
OK, so compression is good so you don't have a weak top end. In your first post you commented that stock jetting was "too rich". My question is what are you basing your claim of "too rich" on ? You are claiming your engine has lean surges at 1/4 throttle correct ? This is a tell tale sign you are too lean, not rich like you are claiming. Problem i'm reading is that you are just throwing multiple jet combinations all at once at your engine without any single carb circut systematic method. For example you are first supposed to do a WOT plug chop to get your correct main jet. Then you work the pilot jet, and if needed adjust your needle clip position. If you are getting lean surging at 1/4 throttle that is most likely your pilot jet. Keep in mind if you have an air leak, attempting jetting is a waste of time.
I run a 165 main, 55 pilot and clip #3 position with great results in temps around 50-70F
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I have a gnarly pipe and powercore silencer and FMF recommended 165, 52, and clip in 3rd. I had to go to the 2nd clip to get mine to run right. I run harescrambles with lots of single track and it will still load up but cleans out and burns fine on the fire lanes. It could probably go to a 50 and be ok. The FMF jetting is for desert or mx according to them at sea level so its just a baseline and will vary depending where and what you are doing with it. Good luck as it can take some time to get it sorted out.
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the surging is only with CLOSED throttle going down hills it lerches back and forth. it runs fine upon throttle only at 1/4 throttle does it studder just like its to rich there. from 1/2 to full runs clean.
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checked the piston for wash and there was none which tells me im way to lean, im going back to stock jetting ride it a while and check the wash heck might need to go richer on the main. seems like piston wash is a better indicator than plug reading