View Full Version : Shimming the Carb Needles... Is it for You?


kkim
November 11th, 2008, 08:56 PM
Shimming the needles, raising the needle jet, the washer trick… whatever you want to call it, it works for our bikes. I would rate this mod as the top DIY one should consider doing to their bike, especially if you’re a newer rider and trying to get comfortable riding it. It really does make the bike easier to ride and boosts confidence, two things any new rider can use.

While this trick has been used on the previous generation 250s, this is written specifically for the new gen (08-09) 250R. Most of the info, though, is general enough to apply to the pregens.

Many seem confused as to what it does and why one would even consider this mod. Still others worry if their bike really needs it and if they are capable of doing it. I hope this post will help clear up a lot of questions and doubts on what the symptoms are of a bike that needs it, why it’s the way it is and how to remedy it.

So, if after you read this post and want to give it a try, post your questions here and we’ll see what we can do to help.

Also, if you have done this mod and like or hate the results, please post your comments here so all that are considering doing this will have adequate feedback to decide for themselves to do this or not.

I just thought it was time to simplify the whole “shimming” decision making process.

Hope this proves useful to those wanting answers.

1- Who needs it and what will it do for my bike?

Shimming the needles will get rid of a nasty lean spot coming right off idle. If your bike stalls, hesitates, hacks or coughs when you are trying to pull off from a stop, you could use shimming. Also, if your bike needs to have the choke on to start it, when the engine is stone cold, and needs the choke on for long periods of time, you should shim.

A great DIY on how to shim is located here…
http://www.kawiforums.com/showthread.php?t=105901 (http://www.kawiforums.com/showthread.php?t=105901)


2- What does this all do?

Well, if your bike is lean, shimming will make the bike seem like it has more power at the very bottom end of the rev range. (2-5K rpm) The power band seems “fatter” which leads to an easier to ride bike. If you are a beginning rider and feel the bike is hard to ride because of difficulty of getting the bike off cleanly from a stop, shimming will do wonders for your riding confidence. Start offs will seem like the bike just gets up and rides away on its own. No kidding… after shimming (if your bike is one that needs it), it will literally transform your engine power characteristics.


3- Why is my bike like this from the factory… is something wrong with it?

Kawasaki designed the 250R with fuel economy and emissions controls in mind when they selected the jetting specs. That they went with the most conservative settings to obtain good advertising results flies directly against the very market these bikes were designed for… namely, the beginning rider. The lean settings make the bike very anemic down low in the rev range which results in a very hard to control power band for the neophyte rider. Instead of having a lot of power right when you let out the clutch from a stop, the lean settings make the bike hard to negotiate cleanly from a stop. New riders have a hard enough time coordinating throttle and clutch engagement. The weak low end power just makes it that much harder for the beginning rider to pull off clean take offs, not to mention worrying about stalling the bike in the middle of an intersection.

My take on this is that the bikes are lean due to incorrect settings of the idle mixture screws at the factory. Whoever is doing them is not setting them correctly... and to make it worse, they are not setting them incorrectly consistently. This means some bikes are waaaayy too lean, some sorta lean, others just right and still others (very few) rich. How many washers you will need will depend on a couple of things. The thickness of the washers you use, the setting of your particular bike's mixture screws from the factory as well as other factors that normally affect jetting. (temp, altitude and humidity) Take all this into account and it is easy to see why there are no golden rules as to how many washers will work best for all bikes.

As is the case with all jetting work, experimentation is key to obtaining jetting perfection. I will say, while you have improved your jetting from stock by using the washers, it is far from perfect, but certainly worlds better than it was from off the showroom floor. For many, this will be all they will ever need to do to improve the jetting to make theirs an enjoyable, friendly bike.

4- Come on… at least give me a place to start!!

Okay, okay… These are some very general rule of thumb washer numbers. Expect to have to do this a couple of times if you are not satisfied with the recommendations…

1 washer for a completely stock bike.
1-2 washers for an aftermarket can or system
2-3 washers for an aftermarket system or can with the snorkel removed


5- Some caveats before deciding you should do this…

Not all people who have shimmed their bikes have met with success. There have been a few that actually installed the washers and the bike ran like crap. They ended up taking the washers back out and their bikes run fine without any washers to this day. Remember step #1? Their bikes never stalled from stops and in fact needed little or no choke at start up. These bikes are the few that were set right or a bit rich from the factory. You need to determine if the situations in #1 describe your bike. If it does, it’s a safe bet shimming will improve your bike.

If you have never worked on a bike before and would like to do this mod, read the DIY link I posted. Read it (the entire thread!) and understand it before you start tearing your bike apart. Have all the suggested tools available, especially the long #2 Phillips screwdriver. It does take some degree of mechanical skill to accomplish this task and some of the parts you will be dealing with are quite delicate. Just be clean and orderly when you work and you should do fine. Do one carb at a time as you don’t want to mix parts up between the left and right carb as some parts are different between the two.

Set aside some time to do this. If it’s your first time tearing the bike apart, plan on 4 hours. Personally, I usually allow double the time on any new project I work on, so for this I would put aside 8 hours just in case something should go wrong.


If there are any questions, please post them in this thread and the members of the board who have done this before will be more than happy to answer your questions and/or sooth your fears.

noche_caliente
November 16th, 2008, 09:40 AM
I followed kkim's advice, and I now have a bike that is much nicer to ride! She was very 'surgey' especially around 4.5-5 k, which is where I would often find myself on back roads.... she was also unpredictable at starts- bogging and then kicking in, which made me rather nervous... I threw a washer in, and not much trouble after that!
Now that it's gotten cooler, it was starting to have issues again, so we threw on a second washer, and all of my troubles went away. :thumbup:

TheDuck
November 19th, 2008, 07:38 PM
I've got 3 washers under mine with pod filters and 120 Keihin jets and Area-P exhaust!

Runs great! Recommended!

NJD022588
November 23rd, 2008, 11:43 PM
I recommend this also.

After a week of having the bike, I put the first set of washers on. This helped so much in stopping the bogging and made a much more solid running bike. The temperatures were around 50-70 degrees at the time and it was great for about a month, but when it starting getting a little colder I found it going back to the original problem so I threw another set of washers on. I'm now riding in sub-30 degree weather without any trouble at all.

By far, this is the best mod I've done!

Jiu Jitsu Player
March 13th, 2009, 05:03 PM
Im seriously considering this mod but I dont really have any stalling or bogging problems right nowand the coldest it ever gets here is in the low 70s. I'll probably wait until I get a new exhaust and then add a few washers. If I were to get an Area P full exhaust- would shimming the needles be enough r would I need a jet kit?

kkim
March 13th, 2009, 05:09 PM
shimming would be perfectly fine if you took the time to fine tune the carb with the correct number of shims. I was running around with my area P and washers for months before I decided to rejet. The bike ran well. in fact if you ever watched my uphill vid, that was done with the AP and washers in the carbs.

I only decided to install a jet kit because I removed my airbox and had to rejet completely at that point, anyway.

Jiu Jitsu Player
March 13th, 2009, 10:01 PM
cool. Thanks- I think I'll hold of for another month or so when I get my exhaust and then I'll shimmy the needles.

kkim
March 22nd, 2009, 03:07 PM
:bump:

TheDuck
March 22nd, 2009, 03:16 PM
:bump:

http://i18.photobucket.com/albums/b123/wtfduck/statements/bump-chef.jpg

hieuster
March 25th, 2009, 11:31 PM
Shimming the needles will get rid of a nasty lean spot coming right off idle. If your bike stalls, hesitates, hacks or coughs when you are trying to pull off from a stop, you could use shimming.

Okay, my bike is stock and is currently having this problem only at cold start. By cold I mean storing in the garage in temperatures of 60s-70s degrees. My bike will start up fine without the choke, but getting it to go from a start will start to hesitate and die, therefore I must use the choke. After the bike has warmed up, there isn't any more hesitation and it's fine from a stop.

Would shimming make the choke not necessary at cold start ups?

kkim
March 26th, 2009, 12:08 AM
shimming doesn't negate the use of the choke. It will aide the bike to warm up quicker and enhance the power at low and the midrange.

hieuster
March 27th, 2009, 01:33 PM
Hi, I just got me a Yoshimura Slip on. How many washers do you think I should use? Also, do I need more washers if I remove the snorkel? Thanks!

Nemy
March 29th, 2009, 03:54 PM
Well it seems most people have success with 2. I would start off with that, though you might need 3 to balance the slip on. That's the route I will be taking anyways once it's warm enough that my hands don't shake and ruin the carbs/needles :D

Has anyone noticed a huge drop in fuel economy? I wanna know how "rich" shimming actually makes it.

kkim
March 29th, 2009, 04:01 PM
I agree, start with 2 and if you think the bike could benefit more, add another.

You take a hit in fuel economy, but you do end up with an easier to ride bike. I'd say roughly 50mpg after shimming depending on how liberal you are with the throttle.

Nemy
March 29th, 2009, 04:17 PM
You take a hit in fuel economy, but you do end up with an easier to ride bike. I'd say roughly 50mpg after shimming depending on how liberal you are with the throttle.

lol I'm not even getting that economy right now :(. Breaking her in motoman method is brutal!

kkim
March 29th, 2009, 04:20 PM
Just ride the bike as you need to, to keep up with traffic. That should be plenty to seal the rings. No need to ring it's neck all the time, though it is fun. :)

Viper-Byte
March 29th, 2009, 05:25 PM
I myself have not noiced the fuel economy difference at all... Before doing any engine mods and after the engine had a few 1000kms on it I would get 340km out and fill up with about 14L, I am still getting that with Dynojet jet kit 98 main needle, Areap Full QC and snorkell out. A few fills ago I got 350km and I only filled with 13.5L... I guess it depends on the right hand, though I have been going harder with the mods :D

paterick4o8
April 11th, 2009, 08:18 PM
You take a hit in fuel economy, but you do end up with an easier to ride bike. I'd say roughly 50mpg after shimming depending on how liberal you are with the throttle.

Another good write-up Kkim. how'd I miss this one?
I too seem to get about 50mpg with mixed city and highway riding.

Bo21
April 15th, 2009, 06:20 PM
No washers on mine. I don't have any hesitation at start up. I use the choke for a few blocks and shut if off. After starting it the first time of the day, the choke really is not needed to start the rest of the day.

In my case, I have not even considered doing this mod.

kkim
April 15th, 2009, 06:23 PM
No washers on mine. I don't have any hesitation at start up. I use the choke for a few blocks and shut if off. After starting it the first time of the day, the choke really is not needed to start the rest of the day.

In my case, I have not even considered doing this mod.

you are one of the fortunate few to have a "good" one from the factory. :thumbup:

Jiu Jitsu Player
April 15th, 2009, 08:16 PM
Before I didn't have any hesitation at start up either but riding in 1st was sometimes a bit jerky. I shimmed the needles and pulled the snorkel and it almost doubles the performance of the bike. There is a huge difference in low end power and up past 9/10 RPM it is a whole new machine. I haven't even got my aftermarket exhaust yet but with the power increase and the deeper engine roar it almost feels like I got one already. I can't say enough good things about this simple mod and props to Kkim for helping me through it!

tjkamper
May 19th, 2009, 04:20 PM
Kim:

The bike is currently stock and only time I have ever experienced any bogging is if the bike is extremely cold and I am carring a pasanger (then we weigh together about 300 pounds). When I am alone I have no problem. I open the choke to start but after about 10-20 seconds I can close it and it idles just about 1400rpm. I currently get about 53 MPG mostly highway.

Should I do this mod or should I leave well enough alone?

Also I was thinking of removing the snorkel. If I do then I think I will definitely need to shim it, but until I decide to remove it what should I do?

kkim
May 19th, 2009, 04:27 PM
Travis,

If you are happy with how the bike is running, leave it alone. The shimming idea came about for people that were having real problems with stalling and a hard time moving off from a stop even after the bike was fully warmed up. Sounds like you may have been one of the lucky few that got a bike that wasn't lean from the factory.

Once you do remove the snorkel, though, you will most likely need to shim.

ShishkaBOMB
May 22nd, 2009, 09:10 AM
I was searching for threads about "throttle lag" and found this one which i think might describe my situation.

My bike only has about 230mi and this just started to happen recently for some reason.

I noticed when i first took it out for a ride, pulling out from a stop and in first gear i would put the clutch into the usual friction zone while revving up to about 2000rpm. What was odd was that it didn't rev! I had to open the throttle a little bit more but by then it would just jump up out of nowhere.

I now have the bike on stands and the fairings off and am trying to fix this problem. I thought maybe it was throttle adjustments, but it seems fine. Bike is a CA model, 08, 230mi, idles at 1300.

When i start the bike it usually hesitates a bit, in cali warm weather. It will then idle after a bit of working but sounds like it's struggling. So i would put on the choke for a few seconds then turn it back off and get on my way. I try to start it up without the choke but it would be easier if it were on.

Anywho, when i slowly rev the bike it it seems fine. But if i were to open the throttle a little quicker it would lag, count 2 seconds, then it would jump up high. Sometimes it would stall.

Does shimming sound like what i need? Or could it be something else?

Thanks!

Snake
May 22nd, 2009, 09:19 AM
KKim,
If you mod your bike with a full exaust and filter pods will shimming alone be sufucient or do you still have to get a jet kit?

Cali619
May 22nd, 2009, 09:34 AM
I am assuming that people having the hesitation are rolling on the throttle not just cracking it on?

NJD022588
May 22nd, 2009, 09:41 AM
Does shimming sound like what i need? Or could it be something else?

It sounds like shimming will fix your problem. My behaved similar to this before shimming.


KKim,
If you mod your bike with a full exaust and filter pods will shimming alone be sufucient or do you still have to get a jet kit?

Good question. In addition, if shimming is sufficient, what is the advantage of a jet kit?

NJD022588
May 22nd, 2009, 09:46 AM
I am assuming that people having the hesitation are rolling on the throttle not just cracking it on?

Yes. And giving alot of throttle quickly will cause it to stall.

Cali619
May 22nd, 2009, 09:49 AM
Yes. And giving alot of throttle quickly will cause it to stall.

K just making sure nobody is confused in the difference on rolling on the throttle smoothly and quickly than snapping it on. I am sure doing the latter no amount of mods will not cause hesitation.

Brad Turner
May 22nd, 2009, 11:47 PM
So, this will be my first "tech" post. Please be gentle.

Will shimming the carb needles be sufficient enough to allow me to run an aftermarket slip on exhaust. All of the research I have done almost everyone has said that if you are gonna run an aftermarket slip on, you have to rejet to avoid long term damage to the engine by running it to lean with the stock jets. How do you guys feel about this? Does it matter?

kkim
May 22nd, 2009, 11:50 PM
This is an excellent, easy way to richen up the mixture in the low-midrange to bring the bike alive. I would think with a slip on and removing the snorkel, you would be very happy with the results.

kkim
May 22nd, 2009, 11:59 PM
I was searching for threads about "throttle lag" and found this one which i think might describe my situation.

My bike only has about 230mi and this just started to happen recently for some reason.

I noticed when i first took it out for a ride, pulling out from a stop and in first gear i would put the clutch into the usual friction zone while revving up to about 2000rpm. What was odd was that it didn't rev! I had to open the throttle a little bit more but by then it would just jump up out of nowhere.

I now have the bike on stands and the fairings off and am trying to fix this problem. I thought maybe it was throttle adjustments, but it seems fine. Bike is a CA model, 08, 230mi, idles at 1300.

When i start the bike it usually hesitates a bit, in cali warm weather. It will then idle after a bit of working but sounds like it's struggling. So i would put on the choke for a few seconds then turn it back off and get on my way. I try to start it up without the choke but it would be easier if it were on.

Anywho, when i slowly rev the bike it it seems fine. But if i were to open the throttle a little quicker it would lag, count 2 seconds, then it would jump up high. Sometimes it would stall.

Does shimming sound like what i need? Or could it be something else?

Thanks!

I think you have several problems here. First, you should be using the choke when you start the bike, unless the bike is already warmed up. Full choke, hit start button... bike rumbles to life and will eventually rev/idle at about 3k. I decrease the choke so the bike idles at about 2.5k. As it warms up, the idle will go back up to 3k, so you need to keep playing with the choke to keep it around 2.5k. After a few minutes, you can turn the choke off and the bike should idle at around 1500rpm.

Until the bike is fully warmed up (about 10-15minutes of riding w/ stock jetting), the throttle will have that noticeable lag if you gas it quickly. After the bike is warm, it should improve, but don't expect instant throttle response, even when warm, due to the CV carbs the bike comes with. It's just a characteristic of the carbs' design.

Whether you need to shim is another question, but shimming will not fix what you have described here.

kkim
May 23rd, 2009, 12:03 AM
KKim,
If you mod your bike with a full exaust and filter pods will shimming alone be sufucient or do you still have to get a jet kit?

You don't "have" to, but a full jet kit offers a bit more/easier adjustability than the stock needles do.

You could get excellent results by experimenting with shimming the needles, changing the mains and readjusting the mixture screws if you went to a separate pod air filter setup/full exhaust.

kkim
May 23rd, 2009, 12:07 AM
Good question. In addition, if shimming is sufficient, what is the advantage of a jet kit?

R&D on a kit that was dynoed to give you a desired result. That and the proprietary needles they provide that you can adjust in 5 steps to tune the midrange.

They also give you a selection of mains so you can dial in the full throttle power to your particular location. Some jet kits even provide you new pilot jets to richen up the idle mixture for a smoother, more powerful low end/off idle response.

Brad Turner
May 23rd, 2009, 12:09 AM
This is an excellent, easy way to richen up the mixture in the low-midrange to bring the bike alive. I would think with a slip on and removing the snorkel, you would be very happy with the results.


I think my biggest concern is long term reliability. How will this effect the bike down the road after XXXX miles?

kkim
May 23rd, 2009, 12:12 AM
Actually, if done correctly, the bike will run cooler than the stock jetting after shimming, so I would say longevity would go up.

The extra wear and tear you'll provide from wringing the bike out because it's so much more fun after you shim is an entirely different matter. :D

How long do you plan to keep the bike? :)

OrlandoF0891
May 26th, 2009, 01:31 PM
I wish i would have read this thread before doing the mod. My bike is completely stock, and i put 2 washers on both needles. Put the gas tank back on tested it out and it kept dieing when i gave it too much throttle. So this thread would have saved me a lot of time.

At least going back and having to take the needle out to remove the washer went 5x faster (and thats no exaggeration) because i now knew what to do and had some technique to getting to those tough screws.

kkim
May 26th, 2009, 02:43 PM
what size washers did you use?

OrlandoF0891
May 26th, 2009, 03:45 PM
Sent you a PM

tpelle
June 5th, 2009, 10:03 AM
First post here, and a question:

This mod looks like it only affects the mixture at close-to-idle. Do I assume that MPG will not appreciably be affected?

Cali619
June 5th, 2009, 10:08 AM
First post here, and a question:

This mod looks like it only affects the mixture at close-to-idle. Do I assume that MPG will not appreciably be affected?

The mod affects the entire power band of the bike, increased fuel to balance out mods that may have increased air flow like exaust or air filters etc. I think it may make a very insignificant decrease in mileage(I get like maybe 5 miles less a tank). The increase in performance is significant...

kkim
June 5th, 2009, 10:47 AM
First post here, and a question:

This mod looks like it only affects the mixture at close-to-idle. Do I assume that MPG will not appreciably be affected?

define appreciably. :D

miks
June 5th, 2009, 06:57 PM
It probably will drop a tad because the bike would be so much better to ride, tempting you to twist the throttle a little more.

bikermunda
June 15th, 2009, 01:02 AM
i really want to shim the needles but i dont think i will be able to do it myself :( i am not sure how much the shop will charge me for that but i am assuming it will be around $100 wish there was someone from the forums who lived close by to do the shimming for me

kkim
June 15th, 2009, 01:06 AM
Start a new thread asking for help in the bay area and see if there is someone in your area responds. :)

im_a_ninja
August 6th, 2009, 12:07 AM
Ok, I definitely need this mod....where are you guys finding these washers? Where can I gt them?

Thanks!

kkim
August 6th, 2009, 01:30 AM
http://www.ninjette.org/forums/showthread.php?t=24845&

Javi
November 5th, 2011, 11:39 AM
I just want to make sure I get this right. For a complete stock 2012 250R 1 washer, what if I remove the snorkel? Would that be 2 washers? Thanks :)

ladyninja08
November 5th, 2011, 03:45 PM
I DEfinately need this mod done. Will a dealer do this for me or is it done as a DIY only. And what exactley does this do that makes it run bettter? I have the bogging starts no matter how warmed up I get it and it is a concern especially at red lights. Thanks for the info.:)

Momaru
November 15th, 2011, 06:26 PM
I DEfinately need this mod done. Will a dealer do this for me or is it done as a DIY only. And what exactley does this do that makes it run bettter? I have the bogging starts no matter how warmed up I get it and it is a concern especially at red lights. Thanks for the info.:)

If you haven't found an answer yet...
Usually a dealer will suggest/direct you to buy a jet kit (usually $90), in addition to the labor cost for installing it and dialing it in. The jet kit would have adjustable needles in it that would allow finer tweaking than using stock needles and washers, as well as parts for altering other parts of the fuel flow regulation system. The washers are almost exclusively a DIY, unless you've got a very good, flexible shop.

Essentially adding washers under the needles adds more fuel (richens the mix) in the midrange where our bikes are notoriously lean from the factory. A jet kit would also include a range of main jets to adjust the top end fuel flow. If you're sticking with a stock intake-exhaust setup, washers will likely be about all you need, maybe a little fiddling with the pilot jets (control gas flow for very low end/idle, but can affect flow across the range), which is fairly easy if you're patient and have a few tools on hand.

ladyninja08
November 15th, 2011, 08:05 PM
Thank You Momaru. I probably will buy a kit and have the dealer do the work. The dealer quoted me 3 hrs labor and its a lot too involved for me . Thanks for explaining it.

choneofakind
November 15th, 2011, 08:11 PM
3 hrs labor ??? if it's a little too involved for you, find a friend who is mechanically inclined and experienced working on cars/bikes and read through some DIY's and take a crack at it. 2 heads is better than one. If you can't get it right, set it all back the way you found it and then go to the dealer to have them jet for you.

3 hrs labor is awfully expensive for something that just requires patience and time :2cents:

Momaru
November 15th, 2011, 09:25 PM
May take a few hours to get things dialed in. The 'two washers' suggestion is just that; doesn't work for everyone. But I agree that 3 hours is a little much. An experienced mechanic (or owner) can get the bike stripped/dressed in 15 mins or less. A few more for the tank and you're there. Maybe two hours, if they need to strip/dress the bike and have to make a few separate runs to pick good settings.

That said, proper tuning can be an all-day job, but you very very rarely get that with just a straight up kit install.

ladyninja08
November 16th, 2011, 08:07 PM
Thanks guys I will check into some more quotes and look into recruiting a mechanical inclined helper as well

cbdallas
November 17th, 2011, 11:53 AM
I think I want to give this a try..just wanted to make sure this is really as simple as the instructions said. Remove the cover, pull the needle out, slide the washer(s) onto the needle, and put the needle back in? Is it really that easy, other than making sure the boot stays seated & the spring is aligned during re-assembly?

Momaru
November 17th, 2011, 05:56 PM
I think I want to give this a try..just wanted to make sure this is really as simple as the instructions said. Remove the cover, pull the needle out, slide the washer(s) onto the needle, and put the needle back in? Is it really that easy, other than making sure the boot stays seated & the spring is aligned during re-assembly?

After removing the fairings & gas tank, pretty much it is that simple.

Few other warnings/suggestions though:
The carb caps are under spring pressure, so they may pop up at ya. Make VERY sure you don't poke a hole in the diaphragm (expensive to replace and a pain to repair) and that you get the needles back into the correct carb side. I'm not 100% sure about pre-gens, but the new gens have two different OEM needles (one per carb/cylinder) and it matters which side is which. The washers will sit "under" the needle, so they will fall off into the diaphragm (what you called the boot) if you don't hold onto them while re-loading the needles. And finally, pay attention to where the vacuum lines go/how they're routed BEFORE you take things apart. You might even label them with some tape if you're not sure... Most of the hoses are pretty easy, but there's a few that are easy to mix up.

cbdallas
November 18th, 2011, 09:02 AM
I tried this mod last night. No go. Everything came apart & went back together perfectly. The bike fired right up and ran on choke exactly how it normally does. Reved it up a few times, seemed to be fine. Kicked it into first, and it choked and died as I attempted to accelerate out into the street. Fired back up & attempted to ride. HUGE dead area between 2000 + 6000 RPMS, then, like an engine with big turbo lag, it would pick up and haul ass after 6000.

The O.D. of these washers was a couple mm smaller than 3/8, so I thought they'd work. When I took it all apart again, the washers had gotten lodged in the plastic retainers on the bottom of the springs, which caused the needles to stick in the 'up' position. Naturally, this causes very bad running <6000 rpm.

Should the needle be sliding up and down through the washer, or should the washer be traveling up with the needle? Whatever the case, the washers traveled upward, got stuck and then the needles couldn't drop back down.

So...should I be using smaller washers so they can't get stuck in the retainers, or larger ones so the retainers sit on top of the washers?

Removed the washers & re-assembled. It runs exactly like it did before, so I don't think there's anything wrong anywhere.

cbdallas
November 18th, 2011, 11:11 AM
Update: Dug into it again and added a tiny neoprene washer to each needle. Fits snugly around the top and up against the head of the needle. A hair thicker than the stainless steel washers that didn't work.

I don't notice a huge difference, but there seems to be a little better response off idle.

Momaru
November 18th, 2011, 05:15 PM
That range you're having problems (2k-6k) is largely controlled by the pilot screws, I'd look through some of the other tuning DIYs (this one (http://www.ninjette.org/forums/showthread.php?t=10246) by Vex is the main one for pilot jets here, and this is the one (http://www.ninjette.org/forums/showthread.php?t=11963) for shimming the carb needles, by Kkim). Frankly I'm too braindead from work to make a suggestion about which way you want to adjust the pilot screws, but I *think* you may want to push them in a smidge, as raising the needles has introduced a lot more gas in the midrange, possibly richening the mix overmuch. Definitely take a look through the tuning DIYs, or go to thedark side & read thru the intake FAQs @ ninja250.org (http://faq.ninja250.org/wiki/Category:Intake)

Regarding the washers; the needle, washers, and retainer all move together as the boot moves up and down with the diaphragm. Doesn't matter overmuch that the washers were a bit too snug in the retainer, so long as the retainer fit snugly on the needle top to keep it from coming up on its own (the spring & retainer are there to keep it seated in the plastic part of the diaphragm slide (hard plastic part).

cbdallas
November 19th, 2011, 08:48 AM
The 2K - 6K problem cleared up when I replaced the #4 washers with some tiny neoprene ones that fit snugly under the needle heads. I think what happened was the steel washers lodged in the retainers at an angle, trapping the needle where the head wasn't seated at the top of the retainer like it should be. When I pulled the springs out, the needles and washers came out with them. Everything's solved now...running great. My mixture screws are still sealed, so I won't be messing with those unless I experience a running problem. I really don't want to take the carbs out.

Momaru
November 19th, 2011, 11:09 AM
Huzzah! Glad you got things figured out. I'd assumed the washers were sitting flat, & allowing your needle to behave normally, glad you tracked it down!

Some materials don't do so well in environments rich in gasoline & fumes, might want to check on them in a weeks to see how that rubber's holding up.

I agree re: messin' with pilots/other tuning; if it ain't broke, don't fix it :P

choneofakind
November 21st, 2011, 08:08 AM
Good idea to check the neoprene ones just in case :thumbup:

if the rubber ones give you any trouble, the metal washers that work are SAE #4 washers (i believe). they're barely larger in diameter than the head of the needle and don't have any issues hanging up on anything.

cbdallas
November 21st, 2011, 08:32 AM
That kinda makes me wonder what I bought. The package said #4, so I went with it. Hmm....

I'm hoping the washers I used will be ok, since they are actually un-used parts I bought for my '94 Ninja carb a few years ago. (92055 RING-O,PILOT ADJUST). They sit on top of the pilot air screws, but since they fit the jet needle perfectly, I went with them.

evi1joe
November 21st, 2011, 06:13 PM
-- I'm about to put two or three washers in since it's much cheaper and easier than rejecting with new needles. Since it'll have a new exhaust, I may then pull the snorkel out and see how it likes that, too. I'm not looking to race...I just want the better sound and looks and weight of exhaust, but don't want it to run too lean or rich or hurt my engine.

I'll be reading up on how to determine whether it's too rich or lean.

How much do dealerships charge to rejet (after you pay for the $90 dynojet kit)?

choneofakind
November 21st, 2011, 06:26 PM
How much do dealerships charge to rejet (after you pay for the $90 dynojet kit)?

too much for how easy it is if you do it yourself. People have posted here that their dealership quoted them 3 hours work time to re-jet.

If you want to rejet, learn how to diagnose carbs, and then do it yourself. Then get it dyno'd to get the mix perfect if you want the bike running perfectly. If you try a million different combinations of jets and washers and still can't seem to get it right, then put it all back the way you found it, and take it to the dealership to have them do it for you

675Raisinator
March 21st, 2012, 10:17 AM
what size washers do you need?

choneofakind
March 21st, 2012, 02:12 PM
SAE #4. Basically as small as you can find.

VT FIJI Graphix
April 20th, 2012, 11:32 AM
I'm pretty sure my bike (stock '08) has the usual symptoms of a bike that should be shimmed. It has a hard time starting unless it's on full choke, rough idle initially, takes around 10 minutes to warm up, etc. However, I do smell a pretty strong gas smell from the exhaust. This is usually a sign of the bike running too rich, correct?

toua70
June 23rd, 2012, 07:01 PM
So shimmed my carbs today and runs like crap around 7k rpm :( it's struggles and decreases in power up until 10,000 rpm... any suggestions?

tonyklbo
November 13th, 2012, 01:40 PM
Will this MOD void my factory warranty? :(

vmax
November 22nd, 2012, 08:38 PM
Hi all, I am a new member here. I just want to ask my bike don't have any problem hesitate or bog with stock muffler or slip on muffler from stop to take off. I try to shim 1 washer each needle but my bike is not rev as stock jetting, then I try to add 1 washer again, but at 7k rpm, they like hesitate then rev to 10k. So my question here, should I shim my bike?
thanks.

ps : mixuture set L (2 1/2), R (1 3/4). PJ 38 MJ 98

ricomtzjr
November 28th, 2012, 10:42 PM
2012 with 1800 miles. Bought new with 1 mile on it.

Here in El Paso, TX the temps are usually in the 30-40s in the morning, warming up to the 60-70s in the afternoon. I am at about 3800ft and in a dry/dusty environment. In the morning, the bike has a tendancy to bog for a split second, then take off into the higher rpms. The bike tends to seem more powerful at high rpms while cold. Once the bike is at operating temperature, the low-mid power smooths out and top end seems to tone down. From my limited knowledge, I am assuming that I should at least start with one washer. Maybe later go one size larger on the main. Am I correct on my assumption?

My bike is completely stock, snorkel and all.

ricomtzjr
December 29th, 2012, 10:40 PM
Completed this modification. Went with (2) #4 washers for each. I have noticed something different though. Now with the shimming, I notice easier starting, but also noticed that when I let off the choke to fast, it dies. This mostly happens when it's cold. The temps are in the 20s-30s in El Paso, and slightly higher in S.A. and the Dallas area. I didn't notice it so much in S.A. or the Dallas area though.

Could the shimming and decreasing cold temperatures cause this to happen? completely stock, I did not notice any sudden stalling when I reduced choke. After modifying, I have to slightly move reduce choke otherwise I will see spikes and sudden drops in idle as well as stalling. Other members on this forum said it could be a result of a cold engine. I will go ahead and check/adjust the carb sync.

Once the engine is warm, I don't have any issues. It runs great. I do get a small fuel smell from the exhaust. Could this be a rich condition causing the erratic up/down idling and stalling while cold? I will remove one washer from each side and see where I end up after that. I will keep you all posted.

geeker
December 29th, 2012, 10:57 PM
How soon are you turning off the choke? As it gets colder, the warm up time increases, as does the time you should leave the choke applied. As the bike warms, you should decrease the amount of choke a bit at a time until completely off. Not all at once.

ricomtzjr
December 30th, 2012, 11:09 AM
It will do the same if I do it after 5 minutes. I will record it and post the video.

LNasty
December 31st, 2012, 12:42 PM
I have a Leo Vince Slip on on my 2012 250. When i decelerate it makes small backfire pops. also takes a while to warm up even with choke fully on. Have not removed the snorkle either. Live at sea level and have 1600 mile on it. Should I shim the needles? would that take care of the problem?

DaBlue1
December 31st, 2012, 07:35 PM
I have a Leo Vince Slip on on my 2012 250. When i decelerate it makes small backfire pops. also takes a while to warm up even with choke fully on. Have not removed the snorkle either. Live at sea level and have 1600 mile on it. Should I shim the needles? would that take care of the problem?

Popping on decel comes when you quickly and completely close the throttle, doing so causes a lean condition. Ease the throttle closed.

One reason you hear it (popping) so well is because you have an empty tin can instead of a heavily baffled steel drum. The popping noise can be reduced by doing the kleen air delete mod, which stops the extra air entering into the already lean exhaust. You can also shim the needles to add a tiny bit of richness to the mix.

LNasty
December 31st, 2012, 09:33 PM
Popping on decel comes when you quickly and completely close the throttle, doing so causes a lean condition. Ease the throttle closed.

One reason you hear it (popping) so well is because you have an empty tin can instead of a heavily baffled steel drum. The popping noise can be reduced by doing the kleen air delete mod, which stops the extra air entering into the already lean exhaust. You can also shim the needles to add a tiny bit of richness to the mix.

Thank you! That helps

dark_beaverezt
January 13th, 2013, 12:38 AM
did the shimming too after i mounted this beastly exhaust, she did run great,,id highly recommend it!

gkarats
November 2nd, 2013, 09:00 AM
Just did this. Added 2 #4 washers per needle and the bike is acting so much better. She seems so happy now :) great mod.... recommended for everyone.... such a huge improvement. ... Thanks kkim

samson12693
September 15th, 2016, 02:07 PM
Hey guys hope this post is not too dead and everyone has not moved on to the 300FI lol wish i could. this is for my wife's bike 2010 snork removed. 2 bothers exhaust. She will not let me get rid of it....likes the sound smh.. so WHATEVER.

removed carbs reset idle screws to 0 turned out 2 1/2 turns each. bike gurrggles and when turn throttle it die etc choke bla bla ... pops a little etc.

stalls freaks her out etc dangerous etc. so today was gonna do the shim thing bought washers etc. said hey let me jack with these screws on the carb again seems like it is to rich...ran screws back in back to 2 1/2 turns still sucks turn back in ran back out about 2 turns bam no hanging just vrrroooom vvrrrrooommm choke is not on and only dies if i dont give it a sec or two between wot pulls sounds great all the way up the rpm band doesn't hang or dip below idle.

do you guys think i should go ahead and shim since i have fairings off etc i have not rode it down the road yet. bike is not totally warmed up other than me cranking idling and messing with screws?

or srcew everything yank carbs buy jet kit etc drop bike off at bike shop say here fix it I dont give a damn about the cost?

RacinNinja
September 15th, 2016, 02:12 PM
If you haven't fully warmed it up and ridden down the road, you really have no idea where the jetting is.

Start with that.

jkv45
September 15th, 2016, 02:42 PM
From what you described, I don't think shimming the needles is going to help. Setting the idle mixture screws to 2.5 turns out usually gets you very close, so it's odd that it won't idle decent. How old is the gas? Air filter good?

A couple things you can do before removing the carbs would be to sync them and check for a vacuum leak in the manifolds that connect the carbs to the engine. I might also drain the floatbowls and look at what comes out. If you have condensation in the gas, or it's bad, no amount of adjusting is going to make it run right.

Sounds like you might need to remove the carbs and go through them. The idle circuit (Pilot Jets and passages for the idle mixture screws) may be partially blocked. Cleaning the carb and jets properly isn't easy (read-up on it before you take things apart - http://faq.ninja250.org/wiki/Intake) , but you'll never get it to run right unless everything is spotless and properly adjusted.

samson12693
September 15th, 2016, 02:43 PM
ok went and rode it everything is the same except for this...bike pulls fine but engine speed is slower but consistent all the way through.so it do not feel like a 2 stroke power bank anymore. however it only goes about 80mph i swear i remember this bike getting closer to 90 95 etc. i am sure it will go faster than 80 so just seems like getting close to max. anyways decided to put the choke on since it adds a little more fuel right... not a true choke from what i read and when that is on it pulls faster through the rpm band and feels like it gets up to speed quicker.

atm it sounds good vrrrroooooom and no spikes did stall on me once but didnt have the choke on and may have not given it enough gas... probably my fault. so what do you think now?

just saw the other post bike would run just would pop and gurggle and the wife would stall it sometimes after it fully warmed up it was more manageable but before we would go ride she would have to crank it up let it run for 5 to 10 to insure it would not die when she took off maybe that better explains were i am at...

so probably need to just clean everything up change coolant ( have to do it anyway bike maintenance) get rid of all the gas, clean carbs, leave the screws at 2 turns because it sounds great runs way better than before i did it with 2.5 turns. shim needles with 2 washers and then play with screws again? fyi didnt ride the bike much since i pulled thae carbs bike has like 1500 miles on it everything was clean however i have put fuel stabilizer in it when it sits for a few months hopefully i wont get roasted for that.

jkv45
September 15th, 2016, 02:48 PM
ok went and rode it everything is the same except for this...bike pulls fine but engine speed is slower but consistent all the way through.so it do not feel like a 2 stroke power bank anymore. however it only goes about 80mph i swear i remember this bike getting closer to 90 95 etc. i am sure it will go faster than 80 so just seems like getting close to max. anyways decided to put the choke on since it adds a little more fuel right... not a true choke from what i read and when that is on it pulls faster through the rpm band and feels like it gets up to speed quicker.

atm it sounds good vrrrroooooom and no spikes did stall on me once but didnt have the choke on and may have not given it enough gas... probably my fault. so what do you think now?

Gas is bad or the jets are partially plugged. Carb needs to be gone through.

Same as before.

plasmagrid
June 10th, 2018, 12:00 PM
So been reading alot about the shimming and got me thinking, since most everything is Aluminum or Brass, should not the washers be of the same material or Nylon?
Are there any down side to using Nylon washers?
Will Ethanol in today's fuel cause issues with the Nylon?

TheDuck
June 10th, 2018, 12:05 PM
So been reading alot about the shimming and got me thinking, since most everything is Aluminum or Brass, should not the washers be of the same material or Nylon?
Are there any down side to using Nylon washers?
Will Ethanol in today's fuel cause issues with the Nylon?

According to this: https://www.calpaclab.com/nylon-chemical-compatibility-chart/

Nylon and ethanol (or gasoline) are compatible. But remember, there is spring tension weighing on those things, and nylon is soft... unless metal is really hard to come by at your location, or you just have an overabundance of nylon washers, I can't see any reason not to use metal. :D

Hope that helps!

plasmagrid
June 10th, 2018, 12:58 PM
According to this: https://www.calpaclab.com/nylon-chemical-compatibility-chart/

Nylon and ethanol (or gasoline) are compatible. But remember, there is spring tension weighing on those things, and nylon is soft... unless metal is really hard to come by at your location, or you just have an overabundance of nylon washers, I can't see any reason not to use metal. :D

Hope that helps!



This is good information, I am thinking of the Nylon washer as to abate from rust forming from the normal metal washers.

choneofakind
June 10th, 2018, 01:56 PM
I never had a rusting issue and just used some generic SAE #4 washers or whatever they were.

Triple Jim
June 10th, 2018, 02:24 PM
I used ordinary stainless steel washers from my #4 washer drawer if I remember right. I selected a set that were 0.020" (1/2mm) thick.

DannoXYZ
June 10th, 2018, 02:57 PM
You only have to worry about galvanic corrosion of dissimilar metals if there’s an ionic solution between them (salt water). Gasoline is non-polar and doesn’t contribute any ions to react with, so nothing to worry about.

plasmagrid
June 10th, 2018, 03:35 PM
You only have to worry about galvanic corrosion of dissimilar metals if there’s an ionic solution between them (salt water). Gasoline is non-polar and doesn’t contribute any ions to react with, so nothing to worry about.

Ahhhh, gotchya.....
:happy100:

Triple Jim
June 10th, 2018, 03:41 PM
Of course there is some alcohol in the gasoline in most cases, and that's polar.

TheDuck
June 10th, 2018, 05:25 PM
No matter to any of the above. If those washers rust, then you're leaving the bike outside and not riding it enough... imagine what the rest of the bike would look like at that point. :D:D:D:D:D