Bike is running lean

MrAtom · April 12th, 2015, 10:41 PM

a while back, I replaced my air filter and I noticed the bike started performing better, but I think it's also running lean because it doesn't immediately return to idle. The RPMs hang for a second. Now, I know it's bad to run lean because the full potential of the bike is not there. but, it's also bad because it causes the bike to get really hot, and it can damage stuff. My bike doesn't seem to be getting too hot according to the thermometer. I'm going to rejet the carbs and shim the needles, but should I be in a hurry to rejet the carbs?

ieathonda · April 13th, 2015, 07:09 AM

Is it just an OEM replacement filter? Most stock bikes tend to do well with a shim or two under the needle. Rejetting may not be needed depending on if you have any other modifications (ie, full exhaust). With my stock bike i did end up running two shims because the midrange was rather "sloppy" in my opinion and that helped to get a little more fuel into the bike at certain rpm's.

refer to this link:
http://faq.ninja250.org/wiki/Washers_for_carb_needles

and this one: http://faq.ninja250.org/wiki/Why_wou..._my_jetting%3F

Ghostt · April 13th, 2015, 07:24 AM

Agreed @ieathonda do the shims first.

MrAtom · April 13th, 2015, 03:08 PM

Yeah its just the stock filter. Ill shim it and report back!

Ghostt · April 13th, 2015, 03:53 PM

Also don't forget to tune the idle mixture screws.

Quote:

Your initial setting should be 3 full turns out from the bottom, remember just slightly tighten them, don't go all Conan on them.

Then warm it up, slowly turn 1 side pilot screw in until the rpms drop, then back out till RPM's peak (and no further)* Twist throttle...see how it reacts...tweak to taste.
Repeat on other side... test ride. You're looking for best throttle response and transition from just cracked to 1/4 throttle opening or so.*

Thats a quickie, 10 cent tutorial on setting pilot screws.**

April 12th, 2015, 10:41 PM	#1
MrAtom . Name: . Location: . Join Date: Aug 2014 Motorcycle(s): . Posts: A lot. MOTM - July '15	Bike is running lean a while back, I replaced my air filter and I noticed the bike started performing better, but I think it's also running lean because it doesn't immediately return to idle. The RPMs hang for a second. Now, I know it's bad to run lean because the full potential of the bike is not there. but, it's also bad because it causes the bike to get really hot, and it can damage stuff. My bike doesn't seem to be getting too hot according to the thermometer. I'm going to rejet the carbs and shim the needles, but should I be in a hurry to rejet the carbs?

April 13th, 2015, 07:24 AM	#3
Ghostt in your machine Name: Scott Location: Summer Shade, Ky. Join Date: Oct 2014 Motorcycle(s): 98 Ninja 250/F12 aka ZX-2R "SERENITY", 91 Ninja 500/A5 aka ZX-5R "Phoenix", 84 Honda GL1200A "SIREN" Posts: A lot. Blog Entries: 25 MOTM - Jun '17, May '16, Mar '15	Agreed @ieathonda do the shims first. __________________________________________________ *violente et ignorantia* ZX-2R BLOG *Twitter and Instagram = Ghostt_Scott* *I'm not here to change your mind, just to inform.*

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April 13th, 2015, 07:09 AM	#2
ieathonda ninjette.org member Name: William Location: Houston Join Date: Feb 2015 Motorcycle(s): Ninja EX250F Posts: 110	Is it just an OEM replacement filter? Most stock bikes tend to do well with a shim or two under the needle. Rejetting may not be needed depending on if you have any other modifications (ie, full exhaust). With my stock bike i did end up running two shims because the midrange was rather "sloppy" in my opinion and that helped to get a little more fuel into the bike at certain rpm's. refer to this link: http://faq.ninja250.org/wiki/Washers_for_carb_needles and this one: http://faq.ninja250.org/wiki/Why_wou..._my_jetting%3F

April 13th, 2015, 03:08 PM	#4
MrAtom . Name: . Location: . Join Date: Aug 2014 Motorcycle(s): . Posts: A lot. MOTM - July '15	Yeah its just the stock filter. Ill shim it and report back!