July 11th, 2015, 08:34 PM | #1 |
ninjette.org member
Name: Greg
Location: Somerville TN
Join Date: Nov 2013 Motorcycle(s): 08 Ninja 250, 09 650 V-Strom, 07 CRF230F Posts: 42
|
Bogs from 2000 to 2500 rpm
No matter what I do I cannot get this boggy spot from 2000 to 2500 rpm out of my Ninja.
Current configuration: airbox removed, K&N RU-1822's, kleen air removed full AreaP stainless 12" Keihn 40 pilot Dynojet 110 main Dynojet needle with clip #4 from top mixture screws adjusted in until rpm drops, then out a quarter (probably out about 2.5) about 400 ft above sea level outside temp hot as hell in TN in July Carb floats 17mm The bike runs great otherwise. I've tried pilot jets from 38 to 42, different needle settings, everything I can think of. What am I missing, oh great Ninjette hive mind? Its driving me crazy. |
|
July 12th, 2015, 03:54 AM | #2 |
Down Under
Name: Linkin
Location: Sydney, Australia
Join Date: Jun 2014 Motorcycle(s): Kawasaki ZXR250C Ninja Posts: 296
|
As far as my experience goes on tuning with the idle circuit, when the RPM lowers or is raised, you should then adjust the main idle, and tune the next carb.
Start with whichever carb is the main one (on my FZR it is carb #2). To test your tune, the bike has to be fully warm. The testing is easy. Blip throttle. Revs should raise instantly and not bog. Raise throttle slowly and then chop it. RPM should drop straight to idle. Revs hanging higher than idle = lean. Revs dropping below idle or stalling = rich. The engine was designed to run with the airbox. You should keep it. By all means modify it (remove airbox snorkel etc) but pod filters are one of the worst things you can do. Classic scenario - "Help! I replaced the main jets & idle jets with bigger ones! I also put pod filters on. Why does my bike run like ****!?" - Bigger jets mean more fuel yes, but at the same time you have to force more AIR into the combustion chamber, otherwise you run too rich and lose power. The airbox works because of vacuum. You lose this with pod filters. Try using the airbox setup, the standard size idle jet, standard needle clip settings, standard main jet sizes, and standard idle mixture screw settings. Change 1 thing at a time and re-test. |
|
July 12th, 2015, 07:02 AM | #3 |
Rev Limiter
Name: Jay
Location: WI
Join Date: Jul 2013 Motorcycle(s): '06 SV650n, '00 Derbi GPR, '64 CA77 Dream 305, '70 CL450 Scrambler, numerous dirt bikes Posts: A lot.
MOTM - Jun '18, Oct '16
|
You need to isolate the throttle position (1/4, 1/2, 3/4, etc) where you are having the issue.
Use throttle position, not RPMs, to determine which carb circuit is not tuned correctly. |
|
July 12th, 2015, 12:00 PM | #4 |
ninjette.org member
Name: Greg
Location: Somerville TN
Join Date: Nov 2013 Motorcycle(s): 08 Ninja 250, 09 650 V-Strom, 07 CRF230F Posts: 42
|
The problem is from 1/8 to 1/4 throttle. Pilot jet?
|
|
July 12th, 2015, 12:03 PM | #5 |
ninjette.org certified postwhore
Name: .
Location: .
Join Date: Feb 2011 Motorcycle(s): . Posts: Too much.
MOTM - Feb '13, Feb '14
|
1/8-1/4 at 2000 rpm?
Play with your float height. Factory spec says 17mm +or- 2mm. That's a ton of adjustment range. I found with pod filters and floats at exactly 17mm, there was a huuuuuuge hesitation at exactly that range. I could snap the throttle further open and get into my needle range, but parking lots and low speed maneuvers were annoying. My issue was worse when cold than hot. I've since raised the floats 1mm to 16mm height and it seems better. Will try another mm soon to see if that cures it completely. YMMV and this takes some testing. As said above, make one small change at a time and then test. If your issue is worse when cold but goes away some when hot, raise the floats (reduce the float height). If your issue is worse when hot than when cool, lower the floast (increase float height). Also humor us and make sure that there are no broken vacuum hoses or loose vacuum hoses to rule that out as an issue. Vacuum leak can sometimes cause the issue you're describing. As mentioned above, there is a theoretical argument for not using pods on a CV style carb. However, many have had good success on these bikes with using pod filters. They can be tuned well, they do still run reliably, they just make a ton of intake noise getting there and you will notice weather changes more with pods than with the airbox. That said, if you're willing to pull the intake runners out of your stock air box and stick your pod filters onto that, some say that can help smooth out your intake flow and help with consistency. I've found it really just makes the filter easier to remove from the carb to make removing the carb easier so it doesn't have to be maneuvered around the tank bracket. So far, no solid personal feedback on runners vs. no runners because of all the stinking rain the last 4 weeks. Yes, by switching to pods, you lose intake resonance. However, this is not an optimized supersport; they did not spend as much time as they could have in that department. Area P has shown on both the newgen 250 and the current 300 that pod filters make more power than the airbox and can be tuned well to deliver reliable and ride-able fueling. |
|
July 12th, 2015, 12:49 PM | #6 |
ninjette.org certified postwhore
Name: .
Location: .
Join Date: Feb 2011 Motorcycle(s): . Posts: Too much.
MOTM - Feb '13, Feb '14
|
|
|
July 12th, 2015, 01:07 PM | #7 |
Rev Limiter
Name: Jay
Location: WI
Join Date: Jul 2013 Motorcycle(s): '06 SV650n, '00 Derbi GPR, '64 CA77 Dream 305, '70 CL450 Scrambler, numerous dirt bikes Posts: A lot.
MOTM - Jun '18, Oct '16
|
Does it just fall flat, or does it stutter and stumble when you get to that range (1/8 to 1/4 open)?
The new Dynojet needles may be off. I would try the stock needles, and then add a shim, then 2, and test again. It's possible they are too lean or too rich for your particular conditions. If you can get a good idle at the correct speed within the 2 to 3 1/2 turns out on the idle mixture screws I would say the pilot jet is correct. I would also sync the carbs. I was tuning a small 2-stroke street bike that I recently purchased, and it would stumble terribly as I opened the throttle 1/8 to 1/4. It would idle and pull away fine, and pull hard at WOT, but in between it was a mess. I adjusted the clip on the needle up and down all the way without a significant improvement. I decided to get a leaner jet needle ("needle") and it helped, but even at the leanest setting it was still rich. I ended-up getting a leaner needle jet as well - this particular carb (Mikuni flatslide) as a removable needle jet that works with the jet needle to regulate the mid-throttle mixture. BTW, a Mikuni (Sudco) tech I spoke with said that changing the float height does not effect the mixture - which I always believed it did. |
|
July 12th, 2015, 01:18 PM | #8 |
ninjette.org member
Name: Greg
Location: Somerville TN
Join Date: Nov 2013 Motorcycle(s): 08 Ninja 250, 09 650 V-Strom, 07 CRF230F Posts: 42
|
I was wondering about float height which is why I made sure they were set exactly at 17. That's something I'll look at again.
Although I'm pretty sure there is no vacuum leak but I will check to be sure. I tried reattaching the intake runners and putting the pods on them but it had no noticeable effect. As far as reinstalling the airbox, that ship has sailed I think after seeing how well it runs after this one bad spot. |
|
July 12th, 2015, 01:25 PM | #9 | |
ninjette.org member
Name: Greg
Location: Somerville TN
Join Date: Nov 2013 Motorcycle(s): 08 Ninja 250, 09 650 V-Strom, 07 CRF230F Posts: 42
|
Quote:
I've heard yes and no about float height but I think I'll do some adjusting there. Plus or minus 2mm is quite a bit of wiggle room. |
|
|
July 12th, 2015, 02:08 PM | #10 | |
Rev Limiter
Name: Jay
Location: WI
Join Date: Jul 2013 Motorcycle(s): '06 SV650n, '00 Derbi GPR, '64 CA77 Dream 305, '70 CL450 Scrambler, numerous dirt bikes Posts: A lot.
MOTM - Jun '18, Oct '16
|
Quote:
Put them side-by-side with the original needles and compare their diameter and taper. The stock needles are a bit lean, but usually a shim or 2 will richen it up enough to pull strong and cleanly through the range. Have you looked at your plugs lately for an overall mixture? |
|
|
July 12th, 2015, 03:53 PM | #11 |
ninjette.org member
Name: Greg
Location: Somerville TN
Join Date: Nov 2013 Motorcycle(s): 08 Ninja 250, 09 650 V-Strom, 07 CRF230F Posts: 42
|
Plugs look good. Maybe a tad lean.
|
|
July 12th, 2015, 05:54 PM | #12 |
ninjette.org member
Name: Greg
Location: Somerville TN
Join Date: Nov 2013 Motorcycle(s): 08 Ninja 250, 09 650 V-Strom, 07 CRF230F Posts: 42
|
Set the float height at 18mm and it seemed to help. I may leave it alone for a while. Or maybe not.
|
|
July 12th, 2015, 05:57 PM | #13 |
Rev Limiter
Name: Jay
Location: WI
Join Date: Jul 2013 Motorcycle(s): '06 SV650n, '00 Derbi GPR, '64 CA77 Dream 305, '70 CL450 Scrambler, numerous dirt bikes Posts: A lot.
MOTM - Jun '18, Oct '16
|
|
|
July 12th, 2015, 05:58 PM | #14 | |
Wannabe Reborn
Name: Unregistered
Location: Cincy Ohio
Join Date: Mar 2009 Motorcycle(s): Blue 2008 Ninja 250 Posts: 302
|
Quote:
__________________________________________________
" If you're here to show off and prove that your crotch rocket is faster than my Harley, you can leave now. " |
|
|
July 12th, 2015, 06:49 PM | #15 |
Down Under
Name: Linkin
Location: Sydney, Australia
Join Date: Jun 2014 Motorcycle(s): Kawasaki ZXR250C Ninja Posts: 296
|
The restricted size of the intake on the airbox compared to the size of airbox creates a certain amount of vacuum inside. Airboxes are designed so that there is enough vacuum to feed the engine the correct amount of air in relation to the stock jet sizes inside the carbs. Pod filters change this. No airbox, different amount of vacuum, different amount of air, different jets and mixture settings required to get running properly again.
No airbox = improper amount of air = harder to tune. Impossible to tune if your bike has constant velocity carbs as my FZR250R does. You can also mess with the airbox boots. A longer inlet tract (longer airbox boot) will move the peak power and torque to lower in the rev range. The reverse is also true. http://www.f1technical.net/forum/vie...hp?f=4&t=12772 Linkin's FZR250R 3LN3 The main point here is that to tune a bike, you have to change one thing at a time, test ride, and then adjust mixtures/jets accordingly. So, for example. You have a jet kit and pod filters ready to install. If you install the jet get and the pod filters at the same time, you're in the dark as to how to tune the bike. Let's say you have a stock Ninja 250R and you replace the airbox with pod filters. After you do so, the RPM is hanging and will not return to idle. In this situation, the pod filters are allowing more air in, leaning out the mixture. Therefore, you need to adjust the idle circuit to compensate. You'll know you have the correct settings when the bike idles as it did with the airbox. Which means, no bogging down when you twist the throttle, no bogging or stalling below idle speed when you release the throttle, and also no hanging when you release the throttle. That's just for the idle circuit. Moving on to the main jets, after replacing the airbox with pod filters, you'll ideally need a dyno and AFR readings to tune any rich or lean spots. |
|
July 12th, 2015, 08:01 PM | #16 | |
ninjette.org certified postwhore
Name: .
Location: .
Join Date: Feb 2011 Motorcycle(s): . Posts: Too much.
MOTM - Feb '13, Feb '14
|
Ehhhhhhh... I disagree. Let me explain.
Let's take a step back and look at some fluid dynamics. We're going to look at calculating flow through an orifice. The flow rate of a fluid through a hole is a function of the area of the hole and the velocity of the fluid. The velocity is then function of the fluid is based on the pressure differential across the orifice. McNally Insitute writes textbooks and has a good explaination of the math here: http://www.mcnallyinstitute.com/13-html/13-12.htm Now let's look at the carburetor. We have a CV, or Constant Velocity, carburetor. Based on the convergent shape of the carb, air is accelerated through the carb body, and therefore loses pressure as it goes. This is known as the venturi effect and is similar to how and airplane produces lift. This means that at the inlet to the carb (without airbox), air is at atmospheric pressure, while you have slightly less than atmospheric pressure at the outlet of the carb. This means we have a slight pressure differential across the carburetor. This is where our vacuum comes from for things like sucking fuel through the jets, opening the diaphragm in the petcock, etc. It's not "vacuum" so much as a low pressure area in the carb. Since we have CV carbs, their claim to fame is that they attempt to keep a constant air velocity at all operating conditions. How does this happen? We know that when the engine revs faster and we suck air in faster, if we had a fixed size hole, we would create a larger and larger pressure differential across the carb and our engine would find itself limited for air. So one hole size that would work for idle intake would not likely work for full song intake hole size. This is where the slides come in. As your engine revs up and wants more air, instead of creating a bunch of restriction at the carb, the slide lifts, effectively increasing the size of the hole your engine is sucking through. Increasing the size of this hole as your pressure differential goes up flows more air and keeps the air speed constant. This is why the carbs are called constant velocity carbs; they do their best to keep the intake air velocity constant at all operating ranges so that you can meter fuel consistently through jets (using the same theory described above. Pressure differential, orifice size, etc). Now lets move further from the engine and look at the airbox intake and apply our fluid dynamics to that setup. Your pistons move, pull air in. Again, your intake snorkel is a fixed size orifice through which air flows. This means your flow rate can be calculated the same way as above, based on orifice size and pressure differential. However, unlike our CV carbs, this orifice is constant and therefore, while it works well at idle, it presents a restriction as the engine revs faster and faster. At this point (we'll say 12,000 rpm) we have three distinct pressure zones in our intake (ignoring intake pulses due to the valves): we have atmospheric pressure outside, slightly lower pressure in the airbox, and slightly lower pressure than that in the outlet of the carb. The overall limit to flow rate is the airbox snorkel hole. As we both know the limit to power is fuel, the limit to burning fuel is air. To lift this limit, we have two options: 1) modify the airbox to have a bigger hole, or 2) ditch the airbox completely and use a pod filter. The biggest benefit of a basic airbox like this (I say basic because I doubt these cheap airboxes on these cheap bikes have been tuned for intake resonance to pressure the intake. This is where the Hemholtz theory you linked earlier comes in in a perfect MotoGP intake that has been tuned to perfection) is that the airbox supplies a nice consistent flow of air that is in a relatively smooth flow pattern. This is what CV carbs like because of how they work. Remember how the slides lift to keep a constant velocity through the throat of the carb based on pressure differential across the carb? If we have turbulent flow, this pressure differential is chaotic and inconsistent, where if we have a nice clean, perfect flow, the pressure differential is consistent and uniform, leading to smoother slide movement and consistent vacuum in the carb for sucking in fuel. So!!! This means that in a basic air box, the benefit is smooth, laminar flow to create a constant pressure differential across the carb, allowing for more consistency with fueling. Let's say we want to get more air flow, and we cut more holes in our stock air box. Let's say we do this to an extreme and cut off everything past the filter. We basically now have a 5 sided box with a filter making up the sixth side, right? Tell me; what is the difference between this setup and a pod filter on a tube? To further the curiousity, look to Leo Vince, who recommends a pair of 50mm holes be cut in the backside of the stock airbox when their exhaust is installed. This is practically the same setup as I have suggested for thought, an open ended box with a filter. How is this different than a pod filter on an intake runner? I will voice my thoughts here: pod filters are not the bane of a CV carb's existance. Turbulent flow is. CV carbs like smooth flow. So if you can figure out how to reduce the restriction in the intake but keep the air flow smooth, you'll be fine. These airboxes are so simple that I really am not considering resonance to be a major consideration. heck, the pregen was designed in the late 80's and back then the box was stuck on there just to hold the air filter, forget about optimizing intake pressure based on intake pulses Quote:
EDIT: I will say, in a modern superbike or supersport, where the intake is tuned for a specific characteristic of the engine and creates positive pressure in the intake to force air into the engine at a certain speed, I would NOT touch the intake past putting a high flow filter in the box. Those are optimized for lamiar flow, intake resonance, sound, etc etc etc and no average joe is going to be able to touch that. You could put a team of engineers with CFD software at their disposal, but even then, you'll get a different solution out of each team to work on that problem. With old/simpler/cheaper bikes like ours, go for it. Experiment, play, and use the butt-dyno all you want. Slap on a different filter, and change one thing at a time until it runs well. Heck, keep it stock, just don't tell people that the engine runs on vacuum and that ZOMG OEM IS BESTTTTT. You CAN tune these bikes well with a pod filter and rejetting. Reliable, consistent, perfect fueling. Its possible. |
|
2 out of 2 members found this post helpful. |
July 12th, 2015, 08:21 PM | #17 |
ninjette.org certified postwhore
Name: .
Location: .
Join Date: Feb 2011 Motorcycle(s): . Posts: Too much.
MOTM - Feb '13, Feb '14
|
OP!
From what I've experienced farting around with these carbs, check out Factory Pro's instructions because they're pretty good: http://www.factorypro.com/tech/tech_...m_engines.html Main jets, needle height, float height, then idle mixture. Tune those items, in that order. Make one change at a time and then test ride. |
|
July 13th, 2015, 06:55 AM | #18 | |
Rev Limiter
Name: Jay
Location: WI
Join Date: Jul 2013 Motorcycle(s): '06 SV650n, '00 Derbi GPR, '64 CA77 Dream 305, '70 CL450 Scrambler, numerous dirt bikes Posts: A lot.
MOTM - Jun '18, Oct '16
|
Quote:
That's why gains shown on the dyno (not moving) are not necessarily repeatable at speed - when airflow is much more turbulent and creating a vacuum instead of pressure. I also agree that the Ninja's airbox isn't an advanced design tuned for resonance, but it does provide a smoother flow into the carb inlets than pods do. Drilling holes in the back of the box, as recommended by Leo Vince, sounds like a good solution. The sides of the airbox would shield the intake flow from most of the turbulent air rushing by at speed (and creating a vacuum) and also shield it from heat coming off of the engine. Last futzed with by jkv45; July 13th, 2015 at 08:27 AM. Reason: typo |
|
|
July 13th, 2015, 04:11 PM | #19 |
ninjette.org certified postwhore
Name: .
Location: .
Join Date: Feb 2011 Motorcycle(s): . Posts: Too much.
MOTM - Feb '13, Feb '14
|
I mean, most dyno's use some really big fans. Like giant fans. So I still see them as valid data, but you are right.
|
|
July 13th, 2015, 04:17 PM | #20 |
Blind 250 Loving Whore
Name: Tom
Location: Chesapeake, VA
Join Date: May 2011 Motorcycle(s): 2008 250R, 02 FZ1, '20 Fat Bob 114 Posts: A lot.
|
We gotta start getting some 3rd, 4th and 5th gear rolls against a bike like mine and someone with exhaust and stock air box. When you pull a car length on me I'll pull the pods off. Until then they make working on the bike exponentially easier.
|
|
July 13th, 2015, 04:26 PM | #21 | |||
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
|
All the below statements are assuming the carburetors are properly serviced in the first place, and comes from my many years and personal experiences.
Carburetor tuning is a craft, that takes time, patience, proper tools, equipment, and a lot of experience. If you don't have an exhaust gas analyzer, then your just taking the best guess you can so-to speak, and tuning for drivablily, feel, mpg, etc.... But fortunately being there are only so many possible combinations and the Ninjette community is so vast, that the most common setups can be found. Quote:
Quote:
Quote:
__________________________________________________
violente et ignorantia ZX-2R BLOG Twitter and Instagram = Ghostt_Scott I'm not here to change your mind, just to inform. |
|||
1 out of 1 members found this post helpful. |
July 22nd, 2015, 03:56 AM | #22 | |
ninjette.org guru
Name: Larry
Location: Youngstown, Ohio
Join Date: Oct 2011 Motorcycle(s): 06 KLR 650,12 250 Ninja, 86 DR 125, 07 CRF 100, 09 Tomos Streetmate LEL Record Holder, 88 K100 RT Posts: 434
|
a wing and a prayer
Quote:
Short of having a gas analyzer you have to take great notes, have a good knowledge of what does what and a good feel for how the bike runs. I am assuming that the mechanical state of the motor is good..IE good compression, valves adjusted properly etc. This is time consuming but interesting and fun. Wardie
__________________________________________________
wardie |
|
|
July 22nd, 2015, 07:20 AM | #23 |
ninjette.org member
Name: jim
Location: texas currently in Temecula Valley CA
Join Date: May 2013 Motorcycle(s): honda crf230l & 2013 ninja 300se wife has Honda crf230l & honda cbr250r repsol Posts: 222
|
These bikes are higher RPM machines. That RPM seems awful low to worry about boging or a flat spot. Just my 2 cents
|
|
July 22nd, 2015, 03:33 PM | #24 |
ninjette.org certified postwhore
Name: .
Location: .
Join Date: Feb 2011 Motorcycle(s): . Posts: Too much.
MOTM - Feb '13, Feb '14
|
^ yeah, but that's a common RPM to find yourself at when tooling around a parking lot or slowly crossing railroad tracks or making a cautious turn through a neighborhood. When that falls flat on it's face, that's really annoying.
FWIW: lowering the floats helps in this situation. |
|
July 24th, 2015, 07:33 PM | #25 | |
ninjette.org member
Name: Greg
Location: Somerville TN
Join Date: Nov 2013 Motorcycle(s): 08 Ninja 250, 09 650 V-Strom, 07 CRF230F Posts: 42
|
Quote:
I've lowered the floats 1mm with little effect, I'll go down 1 more and then see what happens. |
|
|
July 26th, 2015, 07:53 AM | #26 |
Rev Limiter
Name: Jay
Location: WI
Join Date: Jul 2013 Motorcycle(s): '06 SV650n, '00 Derbi GPR, '64 CA77 Dream 305, '70 CL450 Scrambler, numerous dirt bikes Posts: A lot.
MOTM - Jun '18, Oct '16
|
Have you compared the stock needles to the dynojet needles?
Try putting the stock needles back in and see what the results are. |
|
July 26th, 2015, 09:01 AM | #27 |
ninjette.org member
Name: Greg
Location: Somerville TN
Join Date: Nov 2013 Motorcycle(s): 08 Ninja 250, 09 650 V-Strom, 07 CRF230F Posts: 42
|
|
|
July 26th, 2015, 11:48 AM | #28 |
ninjette.org member
Name: Greg
Location: Somerville TN
Join Date: Nov 2013 Motorcycle(s): 08 Ninja 250, 09 650 V-Strom, 07 CRF230F Posts: 42
|
Stock needles make it worse.
Anybody want to buy a Ninja 250? Runs great above 2500 rpm! Need to sell for something fuel injected. |
|
July 26th, 2015, 01:26 PM | #29 | |
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
|
Quote:
But seriously did you tune the idle mixture screws?
__________________________________________________
violente et ignorantia ZX-2R BLOG Twitter and Instagram = Ghostt_Scott I'm not here to change your mind, just to inform. |
|
|
July 26th, 2015, 02:16 PM | #30 |
ninjette.org member
Name: Greg
Location: Somerville TN
Join Date: Nov 2013 Motorcycle(s): 08 Ninja 250, 09 650 V-Strom, 07 CRF230F Posts: 42
|
|
|
July 26th, 2015, 02:35 PM | #31 |
ninjette.org certified postwhore
Name: .
Location: .
Join Date: Feb 2011 Motorcycle(s): . Posts: Too much.
MOTM - Feb '13, Feb '14
|
Hmmmm... I got mine to work out with a very similar setup to yours, it IS possible. Don't lose hope! That said, the Ninja 300 is a slick machine. The gear box is smoooooooth and the fueling is really nice (the model I rode had a Area P quiet core 18" system and fuel controller with their mapping) and responsive. Power up top is good and mid range is definitely more useful than the 250. Much want. The R3 also looks promising in the little bike category.
What I have: K&N R-0990 with newgen intake runners, full Muzzy exhaust system with 18" can. Jetting: 110 mains, 3 washers on the needles, 18mm float height, 40 pilots, 2.75 turns on mix screws. I can bum down to 2000 rpm in 2nd and snap open the throttle or roll on slowly and it never bogs leaves me hanging. It's not exactly torquey down there, but it doesn't feel unresponsive. Is your 2500 rpm issue more of a problem when engine is fully hot or when you're leaving the driveway for the first time? Does it get better in the evening when it cools down a little bit? |
|
July 26th, 2015, 06:42 PM | #32 | |
Rev Limiter
Name: Jay
Location: WI
Join Date: Jul 2013 Motorcycle(s): '06 SV650n, '00 Derbi GPR, '64 CA77 Dream 305, '70 CL450 Scrambler, numerous dirt bikes Posts: A lot.
MOTM - Jun '18, Oct '16
|
Quote:
I assume you have already gone back to the Dynojet needles. So, as you let the clutch out and begin to open the throttle, does it pull cleanly and smoothly for a time, then stumble as it hits 2500? When it does begin to stumble, what amount of throttle opening are you at? Does the engine speed ever hang-up when you open the throttle and close it quickly? Could you have a vacuum leak? If you use RPMs to adjust the idle mixture, I like to get the highest RPM - then go 1/8 to 1/4 richer. For the Ninja, richer is "out". If you're in the 2 to 3 turn out range, I would say the Pilot Jet is correct. With that pretty close, and with your experience with the needle, I would look at the Main Jet. I would go with basic jetting numbers for your set-up - but ditch the Dynojet jets and go with OEMs. If the Dynojet needles are richer, and they are better than the originals, I would say the Main Jet that is it in it now is too lean. You can also add some choke (enrichener) when the engine is hot (and stumbling) to see if the added fuel make the condition better or worse. |
|
|
July 26th, 2015, 07:55 PM | #33 | |
ninjette.org member
Name: Greg
Location: Somerville TN
Join Date: Nov 2013 Motorcycle(s): 08 Ninja 250, 09 650 V-Strom, 07 CRF230F Posts: 42
|
Quote:
I have the idle set at 1500. As the rpms hit 2000 it bogs and clears at 2500which is about 1/4 throttle. If you open the throttle quickly it bogs and won't recover. Open is slowly and it clears and takes of like a rocket at 3000. If there is a vacume leak I can't find it. I think the idle mixture and pilot jet is correct because I adjusted it like you say. I have a dynojet 112 main in it right now with the clip in the 4th groove, which is what dynojet recommends for this setup. I've considered going bigger but 112 is the biggest I have right now. It doesn't seem to matter if the engine is hot or cold. |
|
|
July 26th, 2015, 08:27 PM | #34 |
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
|
Did you check the enrichment diaphragm? And make sure it works?,
__________________________________________________
violente et ignorantia ZX-2R BLOG Twitter and Instagram = Ghostt_Scott I'm not here to change your mind, just to inform. |
|
July 26th, 2015, 09:40 PM | #35 |
ninjette.org member
Name: Greg
Location: Somerville TN
Join Date: Nov 2013 Motorcycle(s): 08 Ninja 250, 09 650 V-Strom, 07 CRF230F Posts: 42
|
Diaphragm looked good and I'm not getting any popping on decal so I'm thinking it's good.
|
|
July 26th, 2015, 11:09 PM | #36 |
ninjette.org certified postwhore
Name: .
Location: .
Join Date: Feb 2011 Motorcycle(s): . Posts: Too much.
MOTM - Feb '13, Feb '14
|
If you're not getting massive decel piping and really weird idle issues, I wouldn't worry about vacuum leaks because you're good.
Scott, do you mean the slide diaphragms? |
|
July 27th, 2015, 06:44 AM | #37 | |
Rev Limiter
Name: Jay
Location: WI
Join Date: Jul 2013 Motorcycle(s): '06 SV650n, '00 Derbi GPR, '64 CA77 Dream 305, '70 CL450 Scrambler, numerous dirt bikes Posts: A lot.
MOTM - Jun '18, Oct '16
|
Quote:
As others noted, it may be an issue with one of the carb diaphragms, or air passages that operate the diaphragms. You may need to remove them and inspect them closely. Take the air filters off and lift the slides manually (engine off) to see if they rise and fall smoothly. If that's ok, start it up and watch them as you open the throttle to see if they move together. Look over this section - http://faq.ninja250.org/wiki/Intake and confirm that everything is correct. There have been instances where the carb was not assembled correctly but it still ran. Any chance the "collar" (http://faq.ninja250.org/images/e/eb/Jim_carb_2.jpg) was not inserted properly from the bottom before screwing in the "holder"? |
|
|
July 27th, 2015, 04:57 PM | #38 |
ninjette.org member
Name: Greg
Location: Somerville TN
Join Date: Nov 2013 Motorcycle(s): 08 Ninja 250, 09 650 V-Strom, 07 CRF230F Posts: 42
|
My slides are fluttering. A video is worth a thousand words.
The video is 90 degrees out but you get the idea. In case you can't view the video, the slides are fluttering at the troublesome rpm and fuel is being sprayed out of the carbs. So WTH is happening here? |
|
July 28th, 2015, 07:00 AM | #39 |
Rev Limiter
Name: Jay
Location: WI
Join Date: Jul 2013 Motorcycle(s): '06 SV650n, '00 Derbi GPR, '64 CA77 Dream 305, '70 CL450 Scrambler, numerous dirt bikes Posts: A lot.
MOTM - Jun '18, Oct '16
|
Not sure exactly what's going on there, but I would say it's time to pull the carbs and go through them again. Double check that all the passages are fully open, adjustments are set, and everything is assembled correctly.
I personally would remove all of the Dynojet parts, and do some research into a good baseline for your intake/exhaust set-up using oem parts. |
|
August 5th, 2015, 05:55 PM | #40 |
ninjette.org certified postwhore
Name: .
Location: .
Join Date: Feb 2011 Motorcycle(s): . Posts: Too much.
MOTM - Feb '13, Feb '14
|
I had a thought on this. Let me explain. Yesterday, I noticed that at 9000 or so with a medium throttle opening and gradually accelerating, I experienced some light surge. I experimented with raising my needles again and now am at 4 washers on stock needles. Mid range feels good, top end at wot still pulls well, so I'm happy with the main jet. However, my little bog is back, right at 2000 rpm when you give it some gas. :/
I got to thinking. The needle fueling is good; smooth and responsive. But it seems like maybe the slide is raising too quickly when you give it gas down low and that's giving the soggy feeling. Your experiences back this thought, since you mentioned slide flutter. Now I thought about the slide springs. The rate and slide lift feels great in mid range and up top, so I doubt the spring rate is too stiff or too soft, but it seems to be lifting too easily. Why not use a washer between the cap and spring to preload the diaphragm spring???? That would make the needle and slide not lift as quickly, hopefully not swamping it at 2000-2500 when you give it throte, but it wouldn't change the spring rate and potentially mess up the mid range response and quick revving nature when in higher rpm ranges because as we know from suspension, preload does not change the rate, just the amount of force required to initially move. |
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
2009 Bogs Between 3500-4000 RPM | Hatter | 2008 - 2012 Ninja 250R Tech Talk | 2 | March 26th, 2015 09:39 AM |
Just cleaned carbs - now stuttering at low RPM, fine at high RPM | Ohio | 2008 - 2012 Ninja 250R Tech Talk | 20 | August 5th, 2014 10:30 PM |
[motorcycle.com] - Church Of MO 2000 Honda Gold Wing Vs. 2000 BMW K1200 LT | Ninjette Newsbot | Motorcycling News | 0 | May 18th, 2014 07:40 AM |
Bike bogs down at 9K | stubshaft | 2008 - 2012 Ninja 250R Tech Talk | 7 | May 5th, 2014 05:41 PM |
Bogs down when accelerating, max 5-7k RPM | Jeffro2749 | 1986 - 2007 Ninja 250R Tech Talk | 17 | August 25th, 2013 09:03 AM |
|
|