I have heard everyone talking about running rich or running lean, but I am not sure how I would tell if my bike is doing either of these. What are the indications and corrections (jetting?). I have done some modifications to the air box and got a new filter. I am totally ignorant and need some enlightenment.
rich or lean
- Thread starter ZEKEDAWG
- Start date
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What langston said involves the oil/fuel ratio, when you talk jetting your talking about the fuel/air ratio, and this will only confuse you. Rich= high gas/air ratio(not enough air), lean = low gas/air ratio(too much air). A bike jetted too lean will bog, detonate(ping), and no spooge will come out the exhaust, it also may overheat and spit coolant. A bike jetted too rich will sound blubbery, have excessive spooge, somewhat sluggish response, and will run cooler and potentially leave carbon deposits in your engine.
jmics19067
LIFETIME SPONSOR
- Jan 22, 2002
- 2,097
- 0
The only advice I can give you would be to take the top of you carb apart and remove the jet needle. refer to your manual if need be. carefully remove the clip on the needle< it likes to fly and get lost> . I like to lay the needle down on something flat<work bench,tail gate of pickup> so the open ends of the clip are pointing down hold the clip witha pair of needle nose pliers and gently push the needle flat to the work surface the clip should be in your needle nose pliers now.
Put the clip on the next notch down on the needle. this raises the needle out of the main jet slightly richening the fuel air mixture. put the carb back together and ride. If the bike smokes, fouls plugs, blubbers runs worse in the 1/4 to 3/4 throttle setting you have just experience what too rich feels like. If the bike runs smoother/ stronger/ engine sounds healthier no tinny or knocking sounds, you were experiencing a too lean condition and just took a step in the right direction to correct it.
If the bike ran worse during this experiment or you couldn't tell put the clip in the original positon and retest. try and feel the difference between these to settings.
Now try moving that clip up one position ,which is lowering the needle into the main jet, blocking it off more, leaning out the fuel air mixture and test.
If the bike runs crisper/ less smoke/ has more power in the 1/4to 3/4 throttle settings you are now heading in the right direction. If thebike feels/sounds tinny, surges and or knocks stop immediately and go back to the previous setting.Hopefully you are starting to understand how the bike feels between rich and lean and it hasnt costed you anything yet. Now there are two more circuits in the carb , the pilot circuit which is closed to 1/4 throttle setting and the main jet circuit which is 3/4 to wide open.
Canadian Dave's kdx forum has an excellent link on jetting. And remember if the carberator is too rich the bike will be slow, smokes and foul plugs, if the bike is too lean you can cause engine damage. Also understand that there are three different circuits in the carb so it is possible to be lean on the main jet and causing damage at wide open throttle and yet too rich on the pilot jet making the bike smoke/ foul plugs at low throttle .
I hope this helps
Put the clip on the next notch down on the needle. this raises the needle out of the main jet slightly richening the fuel air mixture. put the carb back together and ride. If the bike smokes, fouls plugs, blubbers runs worse in the 1/4 to 3/4 throttle setting you have just experience what too rich feels like. If the bike runs smoother/ stronger/ engine sounds healthier no tinny or knocking sounds, you were experiencing a too lean condition and just took a step in the right direction to correct it.
If the bike ran worse during this experiment or you couldn't tell put the clip in the original positon and retest. try and feel the difference between these to settings.
Now try moving that clip up one position ,which is lowering the needle into the main jet, blocking it off more, leaning out the fuel air mixture and test.
If the bike runs crisper/ less smoke/ has more power in the 1/4to 3/4 throttle settings you are now heading in the right direction. If thebike feels/sounds tinny, surges and or knocks stop immediately and go back to the previous setting.Hopefully you are starting to understand how the bike feels between rich and lean and it hasnt costed you anything yet. Now there are two more circuits in the carb , the pilot circuit which is closed to 1/4 throttle setting and the main jet circuit which is 3/4 to wide open.
Canadian Dave's kdx forum has an excellent link on jetting. And remember if the carberator is too rich the bike will be slow, smokes and foul plugs, if the bike is too lean you can cause engine damage. Also understand that there are three different circuits in the carb so it is possible to be lean on the main jet and causing damage at wide open throttle and yet too rich on the pilot jet making the bike smoke/ foul plugs at low throttle .
I hope this helps
dirt bike dave
Sponsoring Member
- May 3, 2000
- 5,348
- 3
zekedawg -
check out Eric Gorr's page for a tuning overview, including jetting.
http://ericgorr.com/techarticles/carbtuning.html
check out Eric Gorr's page for a tuning overview, including jetting.
http://ericgorr.com/techarticles/carbtuning.html
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