Need Assistance Tuning/Rejetting

[Hatter]

So I began the process of re jetting my 2009 250 today to compensate for the slip-on and pod air filters. I'm having a fantastic time :roll eyes: . On the bright side, i'm a pro at removing the carbs..... I could use some help diagnosing my issues.

Main: 108 Pilot: 40 Mixture: 2 turns

Idles very smooth. Won't Rev past 6k. Plugs appear to indicate it's running rich.


Main: 110 Pilot: 40 Mixture 2 turns

Idles smooth. Occasionally revs to 7-8k (more luck if I roll the throttle, but can't hit the red line. Exhaust smells rich and plugs sooty


I haven't shimmed the needles yet. Could this be the issue? Maybe I have waaaayy too large of jets? I'm thinking of stopping by the shop tomorrow and picking up #100 jets and shims. Any other suggestions?

[subxero]

Originally Posted by Hatter

So I began the process of re jetting my 2009 250 today to compensate for the slip-on and pod air filters. I'm having a fantastic time :roll eyes: . On the bright side, i'm a pro at removing the carbs..... I could use some help diagnosing my issues.

Main: 108 Pilot: 40 Mixture: 2 turns

Idles very smooth. Won't Rev past 6k. Plugs appear to indicate it's running rich.


Main: 110 Pilot: 40 Mixture 2 turns

Idles smooth. Occasionally revs to 7-8k (more luck if I roll the throttle, but can't hit the red line. Exhaust smells rich and plugs sooty


I haven't shimmed the needles yet. Could this be the issue? Maybe I have waaaayy too large of jets? I'm thinking of stopping by the shop tomorrow and picking up #100 jets and shims. Any other suggestions?

don't worry about the plugs until you get the setting some what correct, you are just wasting your time, and even then it is questionable especially if you are not doing it correctly.

with 108's you should still be able to rev the bike out, that is not that rich, when rich typically it will bog in the 8-10.5k range but should still go past there.

I think you have a problem somewhere else, check the boots in the top of the carb and make sure you didn't tear one and they are seated correctly and you assembled everything correctly. Do the same with the bottom of the carb, make sure the floats and the all that jazz are functioning as should. Then check all your hoses and vac lines and what not. (did you remove kleen air system?) make sure you have all those holes blocked off, prime the carb with fuel yadda yadda yadda

at 1/4 or 1/2 throttle if you put the choke on full what does it do to the bike?

what brand jets you using? Did you shim the carb? did you buy a jet kit? 108 with the stock headers will probably be a little rich. I run 108 keihin jets with a full race exhaust and pods to give you an idea

[Hatter]

Alright, so your saying the jetting doesn't appear to be the problem. I'll go through and check everything else. I'll be honest, I have a sneaking suspicion the float level is too low. Using the tube and drain plug method, the fuel barely comes up half way up the bowl. I hate dealing with floats, so I was living in denial

It also appears that #108 is way too large for my needs, I'll pick up a #100 and start from there. What I should have done from the beginning .

I did not shim the needles yet (#4 washers right?). The Air Kleen system has been removed and holes plugged. I'm using JetrUs generic branded jets.

[crazymadbastard]

I suggest checking the valves first, could be that they are too tight and who knows if i ever was done.

If the valves check out fine, then check out the faq on tuning and follow it by the book.

[subxero]

Originally Posted by Hatter

Alright, so your saying the jetting doesn't appear to be the problem. I'll go through and check everything else. I'll be honest, I have a sneaking suspicion the float level is too low. Using the tube and drain plug method, the fuel barely comes up half way up the bowl. I hate dealing with floats, so I was living in denial

It also appears that #108 is way too large for my needs, I'll pick up a #100 and start from there. What I should have done from the beginning .

I did not shim the needles yet (#4 washers right?). The Air Kleen system has been removed and holes plugged. I'm using JetrUs generic branded jets.

I believe those go by the keihin sizing

Even with the 108 in I am surprised it wouldn't rev out. Im using a 108 now, but started at 118 and I could redline the bike with the 118 no problems, just bogged in the lower revs

[DaBlue1]

Temps for your jetting set up will make for a rich mixture. Go 105 on the main jets, shim, put your stock pilots back in and turn them 2.5 turns out, then test. you will see a difference in performance as the ambient temps increase.

[Hatter]

Alright here is a nightly report.

I carefully went over the carbs again and here is what I did/found:

-Changed to #100 jet (#40 pilot) (Sorry DaBlue1, I am getting #105 tomorrow)
-Inspected diaphragms (ok)
-Added two shims
-Adjusted floats
-Inspected all Vac lines (all ok)
-Ensured all boots were undamaged and tight
-Mixture screw at 2.5 turns

The idled normally as usual. Once at operating temp, I was easily able to turn off choke and rev up to 9k, but no further. It's like it's hitting an invisible wall. It's noticeably worse if I slowly roll the throttle than if I just do a quick rev. Turning on the choke after it's warm or during a rev has no noticeable effect. I have not checked the Valves yet

Any other suggestions? Bare in mind, all these tests were done in neutral with the bike on the stand (if that matters)

[jkv45]

Oiled the air filters lately?

Try pulling them off and see if there's any change.

Damaged carb diaphragms could also be the cause.

I would actually ride it, and not just rev it in neutral. When not under load the slides will not lift the same as they do while riding.

[Hatter]

Originally Posted by jkv45

Oiled the air filters lately?

Try pulling them off and see if there's any change.

Damaged carb diaphragms could also be the cause.

I would actually ride it, and not just rev it in neutral. When not under load the slides will not lift the same as they do while riding.

Brand new oil and air filters. I couldn't find any damage of the diaphragms.

You think I may experience different results if I test with the bike under a load?

[jkv45]

Originally Posted by Hatter

Brand new oil and air filters. I couldn't find any damage of the diaphragms.

You think I may experience different results if I test with the bike under a load?

Absolutely. It takes very little throttle opening to get high revs when you have no load.

I would take it for a ride before doing much else. Pay attention to the throttle position where the problems occur. When you roll open the throttle all the way there will always be some delay because of the time it take the slides to lift.

If it runs like it's being choked-off at high RPMs I would remove the air filters and see if there is any change. Over-oiling or using the wrong oil on the air filter can restrict the flow.

Also note if it changes after riding for a while or if it stays consistent the entire time.

Make sure the gas is fresh, and drain the tank if you think it may not be. If temps have fluctuated you can also get a fair amount of condensation in the tank if it has been low.

[Hatter]

Alright, I'll put it back together and take it for a drive and see what happens.

There is no oil on the air filter as I removed the air box and added pods.

The gas is brand new. I drained the entire system after I got it.

[Ghostt]

Have you dialed in the pilot screws yet?

Here's a quick how-to

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.

Personally take the shims out, and let's get it working properly first, once you've done that, then try shims, one change at a time. Also some people here know my opinion of pod filters.

[Hatter]

Originally Posted by Ghostt

Have you dialed in the pilot screws yet?

Here's a quick how-to

Are you referring to the pilot screws or the mixture screw? I was under the assumption the pilot screw only effects the mixture at idle. Also the pilot screw is only accessible with the bowls off and is either screwed in or out.

[Ghostt]

Originally Posted by Hatter

Are you referring to the pilot screws or the mixture screw? I was under the assumption the pilot screw only effects the mixture at idle. Also the pilot screw is only accessible with the bowls off and is either screwed in or out.

Yes I am, and no they don't, here's some pictures to explain what does what

[Ghostt]

The idle mixture screws, are normally capped at the factory, did you remove the caps?? And please explain what is two turns out??

[Hatter]

Originally Posted by Ghostt

The idle mixture screws, are normally capped at the factory, did you remove the caps?? And please explain what is two turns out??

Yes I removed the plugs. tightened the mixture screws and then turned them out 2.5 turns

The pilot screw was swapped to a #40.

[Ghostt]

Originally Posted by Hatter

Yes I removed the plugs. tightened the mixture screws and then turned them out 2.5 turns

The pilot screw was swapped to a #40.

Okay, good, now just dial them in using the above method. What you changed was the pilot jet to a #40

Also when you had the carburetors apart did the check the float height? This is very important and crucial when it comes to setting up carburetors, and also the most overlooked.

Personally I would return to stock jet on the pilot jet, and focus on the main jet only, remember one change at a time, helps eliminate the variables when it comes to tuning.

Once you have have those set and dialed in, the on to the next one. It's a PITA, but it's worth it in then end, otherwise you'll be chasing you tail, so to speak of.

[Hatter]

Originally Posted by Ghostt

Okay, good, now just dial them in using the above method. What you changed was the pilot jet to a #40

Also when you had the carburetors apart did the check the float height? This is very important and crucial when it comes to setting up carburetors, and also the most overlooked.

Personally I would return to stock jet on the pilot jet, and focus on the main jet only, remember one change at a time, helps eliminate the variables when it comes to tuning.

Once you have have those set and dialed in, the on to the next one. It's a PITA, but it's worth it in then end, otherwise you'll be chasing you tail, so to speak of.

I'll give the stock pilots a try.

Floats were measured and adjusted accordingly. So those are good to go

[Ghostt]

Originally Posted by Hatter

I'll give the stock pilots a try.

Floats were measured and adjusted accordingly. So those are good to go

Okay good to hear the floats were set properly to 17mm, that's a great start.

Before you remove the pilot jet, try dialed then in first, and see what the results are. All else fails then return to OEM jets.

Also check for any vacuum leaks issues again.

Something else to keep in mind that NewGen carburetors have a right and left side difference, when it comes to certain things, like main needles for one.

Kawasaki did this for various reasons, so double check what went where.

http://www.partzilla.com/parts/searc...RTS/parts.html

Also another variable is using generic jets, from Jets R Us, be sure 100% sure that they are in fact using the same sizing as Keihin does for CV type carburetors.

http://www.jetsrus.com/FAQs/FAQ_genuine_jets.html

Have you done a road test yet??

[Hatter]

Alright I took it for a ride and here is what I found. This is still with the above setup.

Anything above 1/4 throttle it bogs down and occasionally cuts out. It's completely based on throttle position and bogs down at the same exact location (around 1/4). In fact I hover right below that position and go back and fourth from smooth acceleration to bogging. This is with the bike warm with no choke

[Ghostt]

Stupid question time,

Are you sure the diaphragm slides are in properly? Any vacuum leaks? Any other modifications? Verify petcock functions properly?

did you check float height? This is way we only change one thing at a time.

[DaBlue1]

I posted this before on someone else's thread too-

The pilot jets supply most of the fuel at low throttle openings.
The (idle mixture) pilot screws and pilot air jets affect the carb @ idle - 1/4 throttle position. After 1/4 throttle (or approx 3k rpm) the slides begin to lift.

Motorcycle Carburetor Theory 101

Shimming the needles may help a low end bog and starting problems for some but is mainly affective in the 1/4 - 3/4 throttle range.

[Hatter]

So it would appear that the pilots are functioning normally, but for some reason there is an issue with the either the slides, diaphragm or main jets.

However I think I may have found another issue. While looking at the diaphragms again I noticed that the end of one of the needles (just the end, the rest is straight) was bent ever so slightly. Correct me if I'm wrong, but I believe these have to be perfectly straight or they'll cause problems? I tried straightening them, but it didn't change much.

Also I was looking at the parts diagram and it appears there are two different part numbers for the needles on either side. Are they not the same needle on both sides?

Video of issue: https://youtu.be/1hmVPiM5LCU

[Hatter]

Here is a video to help you guys see what's going on! Basically the same while I'm driving it. Once I reach a certain point on the throttle... Nothing


https://youtu.be/1hmVPiM5LCU



EDIT: Oops! Forgot to edit!

[subxero]

Originally Posted by Hatter

So it would appear that the pilots are functioning normally, but for some reason there is an issue with the either the slides, diaphragm or main jets.

However I think I may have found another issue. While looking at the diaphragms again I noticed that the end of one of the needles (just the end, the rest is straight) was bent ever so slightly. Correct me if I'm wrong, but I believe these have to be perfectly straight or they'll cause problems? I tried straightening them, but it didn't change much.

Also I was looking at the parts diagram and it appears there are two different part numbers for the needles on either side. Are they not the same needle on both sides?

Video of issue: https://youtu.be/1hmVPiM5LCU

needles are the same don't worry about it.

So prior to attempting this rejet when was the last time you road your bike? Was it functioning 100% normal? At this time what was your setup? your exhaust, airbox yadda yadda yadda everything relevant

if your needles were bent i would think that would cause more of a problem in the low revs up to 1/4 throttle as they might not seat properly but as long as they are sliding freely up and down with the slides and are not catching preventing the slides from moving up i can't see how that would cause much problems in the hi revs when you are deep in the throttle which seems to be your problem

how did your needles get bent anyway? Are they the OEM needles?

[alex.s]

the needle slides into the main jet emulsion tube. the slide pulls the needle up based on the vacuum. if the needle tip is bent, it will get stuck in the emulsion tube as it goes down, also it will allow fuel to pass incorrectly, and wont close all the way. replace the needles before continuing with anything else.

[Hatter]

Originally Posted by alex.s

the needle slides into the main jet emulsion tube. the slide pulls the needle up based on the vacuum. if the needle tip is bent, it will get stuck in the emulsion tube as it goes down, also it will allow fuel to pass incorrectly, and wont close all the way. replace the needles before continuing with anything else.

I bought this bike "wrecked" (minor front end <20mph) and have been rebuilding it. So I can't comment on the condition before I purchased it. The previous owner had done the slip on I added the pods and jets, everything else is stock. The bike ran significantly worse before the jets/pods though. Idled ok, but would completely die past 1/4 throttle..... Sooner or later I'll learn to stop buying 'projects'

Now when I say it's bent it's extremely slight. Enough where you can tell with the naked eye but not crazy. I'm not entirely sure what happened to them. I never dropped or knocked them. Just caught my eye when I was shimming them.

[alex.s]

bent is bent

[alex.s]

the fact that it ran like **** while completely stock shows you its more than enough to **** things up

a slipon doesn't make something run like ****.

its also probable there are lots of other issues.

[Hatter]

Originally Posted by alex.s

its also probable there are lots of other issues.

Don't say that.... That's not what I want to hear ..... Let me live in denial

[Ghostt]

I agree with Alex.s

I would recommend PM @ducatiman for your carburetor services and parts

[alex.s]

Originally Posted by Hatter

Don't say that.... That's not what I want to hear ..... Let me live in denial

....man that video you posted.... bike sounds like its running perfectly! you could probably sell it for at least 7 grand

[DaBlue1]

After looking at your video, It may not be your needles. Pull the pods off and look and see if the slides are moving up freely and somewhat evenly as the bike is running. If they are not, they are either sticking or you have a fuel delivery problem.

http://www.motorcycleproject.com/tex...bs_work_v3.swf

[Hatter]

Running without the filters won't cause any problems?

[alex.s]

Originally Posted by DaBlue1

After looking at your video, It may not be your needles. Pull the pods off and look and see if the slides are moving up freely and somewhat evenly as the bike is running. If they are not, they are either sticking or you have a fuel delivery problem.

http://www.motorcycleproject.com/tex...bs_work_v3.swf

the needles are directly attached to the slides. if they are bent they will stick in the tube. which means the slide gets stuck too.

post a pic of the bent needles, op

[Hatter]

Ok so I took off the air filter and found that the slides are indeed moving up and down. I must have been crazy because I also took out the needles and they appear straight, they obviously were not that bad, I might have over exaggerated that guys, I'm very sorry!

Here is the video. You'll see the first part is at 1/4 throttle and slides appear to operate normal, but any further than that, they shutter like near the end.


https://www.youtube.com/watch?v=LOWX...ature=youtu.be

[DaBlue1]

The video was a lil short, but I thought I saw the carbs spitting back some fuel.
Is that right? Is there a real strong smell of gas on the filter? If so, you are seeing reversion.

Reversion is the flow of the air fuel mixture out of the cylinder and into back into the intake manifold. Reversion happens even on a stock engine because the piston is moving up the cylinder before the intake valve closes. This is usually a sign of a needed valve adjustment or the timing is off.

https://www.youtube.com/watch?v=VLLZavItixY

[Hatter]

There is a absolutely reversion. No doubt about it. Off timing may explain my symptoms too....

[Hatter]

Alright guys I have an update. Checked the valve clearances today and everything is within specs. Went over the carb again, nothing.

I'm running out of ideas guys......

[Ghostt]

Originally Posted by Hatter

Alright guys I have an update. Checked the valve clearances today and everything is within specs. Went over the carb again, nothing.

I'm running out of ideas guys......

Describe what you did when you went over the carburetors? Are the diaphragms properly installed? Float height correct?