how to fix carb stumble on 2000+ 9r's? : Kawasaki ZX Forums: Kawasaki Ninja Forum

oldgreenmachine · 08-02-2007, 12:55 PM

title says it all. roll on the throttle and there a little empty spot then more power than should be. how can you smooth this spot out? about 3k rpm on an 01'. i'm sure theres a way... anyone?

zed · 08-04-2007, 06:31 AM

I've heard Ivans Jet Kit is suppose to eliminate this problem

oldgreenmachine · 08-04-2007, 09:44 AM

ivans? anyone else got any ideas. i feel like this should be a simple problem (and popular) to fix.

David · 11-21-2007, 08:29 AM

Recently saw an article addressing this problem in an older issue of Motorcyclist Magazine (maybe '02?) on the 9R. The problem lies in the pilot jet (or slow jet) system being to lean. They didn't want to take the carbs completely apart, so they took just the slides out (with carbs still in the bike) and shimmed the needles up with a washer. This richened up the air/fuel mixture at part throttle and got rid of the stumble.

oldgreenmachinetwo · 11-21-2007, 04:34 PM

... was there any specifics or did it just say they "shimmed" it? size is a pretty important factor ya know!

David · 11-21-2007, 06:03 PM

They did not give any specifics; just a quick reference to fix to a common problem. I would try using a narrow washer one a time until the stumble is gone.

slozx9 · 11-21-2007, 08:27 PM

0.5mm shim

BSSJZX9R · 11-22-2007, 07:57 AM

I have also heard that an ignition advancer helps with this problem

JBradshaw00 · 11-24-2007, 07:45 AM

Whats this shim everyones talking about?

oldgreenmachinetwo · 11-24-2007, 09:08 AM

.5mm? will definately try that. hope it works! really don't like messing with carbs! REALLY. DO. NOT. LIKE.

juan valdez · 11-26-2007, 11:21 AM

A friend of mine bought a '98 zx-9r same time as I did and they both had the 3 grand stumble.I didn't notice it until he mentioned it.basically if I was stopped and held it at 3 grand,it would stumble but on the go i never noticed.I guess the question is how much time do you spend at 3 grand? Is it really an issue ? If it is the before mentioned Ivan is the man I would talk to
also a change in gearing might take it out of equation for you.

fast911ray · 11-26-2007, 06:48 PM

Green..you can fine em' at Radio Shack in packages of 10, I believe. 020" ..and it really works.

oldgreenmachinetwo · 11-28-2007, 03:46 PM

thanks 911! winter project on a friends 9! off to radio shack then...

zed · 11-28-2007, 04:19 PM

Quote:

Originally Posted by oldgreenmachinetwo

thanks 911! winter project on a friends 9! off to radio shack then...

Let us know how it goes. I do remember reading an article about using a shim (can't find the link right now) but it did say that although it worked wonders on the C models, there was no benefit on the E models.

zed · 11-28-2007, 04:25 PM

Here it is

http://www.sportrider.com/tech/146_0...fix/index.html

David · 11-28-2007, 11:42 PM

OK, Feb 2000 Motor Cyclist says "to do it right, you'd replace the slow jet with the next biggest size (stockers are 38's)". You need to remove the carbs to do this, so they tried something easier; remove the tops of each carb and raise each jet needle 0.5mm with a little washer. They say this is an old trick and it is as "effective as ever on the ZX9. An easy modification, and almost free."

David · 07-16-2008, 10:25 AM

So did anyone have any luck using the 0.5 mm washers?

alfredo21 · 01-15-2009, 08:17 PM

I am new. bought a kawasaki zx9r 1998 about two weeks ago learning. I have question are you talking about this, When I take off first and second gear at cruising it feels like jumpy or jerky not like a normal ride. It is hard to keep it at cruising 10 to 20 miles per hour. I need to hold the clutch in to smooth it out. then let go of it and play with the throtle. I do not like the feel. I am used to the cruising relax time not jumpy. Is this what you are talking about. Also I been reading about the chain and lub. Do you know how that is done and when it needs to be done? thanks.

e1_ZX-9r · 01-17-2009, 07:23 PM

Quote:

Originally Posted by alfredo21

I am new. bought a kawasaki zx9r 1998 about two weeks ago learning. I have question are you talking about this, When I take off first and second gear at cruising it feels like jumpy or jerky not like a normal ride. It is hard to keep it at cruising 10 to 20 miles per hour. I need to hold the clutch in to smooth it out. then let go of it and play with the throtle. I do not like the feel. I am used to the cruising relax time not jumpy. Is this what you are talking about. Also I been reading about the chain and lub. Do you know how that is done and when it needs to be done? thanks.

Alfredo. Your 1998 uses a different carburetor model than the 2000 E1, but it sounds like you need to have your carbs synchronized. If the surging remains or if you're looking for more midrange (assuming your 9r's intake & exhaust are nolonger stock, like most here) you could look into raising your jet needle, setting the pilot air screw correctly, and/or reset your float bowl height.

e1_ZX-9r · 01-17-2009, 07:57 PM

Quote:

Originally Posted by David

So did anyone have any luck using the 0.5 mm washers?

Yes and here's the how-to with pictures for the 2000-2001 ZX-9r jet needle raising procedure.

I figured that after repeated carburetor mods to fine tune my bike for my riding style (hard to get it perfect for high & low altitude, believe me!) I might as well document the disassembly procedure and take some pics.

My girlfriend loves the 9. Today we took it for a short spin while the sun was out. We started with a freeway blast so she could hear the 'trapp

then some country roads for some low speed sight seeing.

The surge is gone and I couldn't be happier about it.