It's not fueling, it has to do with traction control.

Thanks Seno. I can see that. I didn't explain further, as I only partially understand whats going on.

Lets see if I can describe what I read several places - further. The KTRC "see's" the wheel speed differences from what it expects to "see" based on it thinking it has stock gearing. And based on that, references certain fuel, and timing, and secondary fly positions to compensate for those readings. When the sprocket gearing changes, its relative speeds to each other changes differently which causes the PCM to look in different "maps" for what should be happening. And when the values differ greatly, you get the stutter.

If I'm wrong, please tell me. But this is the best way my brain can figure out what I've read.

* Last updated by: rod442 on 5/17/2014 @ 4:28 AM *

magzx12r,

If you go up one in the rear, go down one in the front, the one from the zephyr is what people say to use, that should solve the problem, I don't know if anyone knows, why it happens ...

Do you have a flash with fueling in each gear ?

To solve this problem in the flash, the maps not just for fueling, but for ignition AND secondary throttle plates have to be unified not just across all cylinders but across all gears. Once this is done the stumble disappears. Again verification that the three maps are indelibly tied together. These maps even with TC-off, are tied together. Make them work together as designed and the result is absolute flawless power delivery. Interupt the way they work together with pigs or flawed number sequencing and the result is flawed. Just my 2c.

I don't have a flash yet. That is one of my future mods. For now, I just swapped back to the stock rear sprocket.

I knew Cblast would know, he knows what all those numbers in the ECU do, me, not so much LOL !

I read about those stumbling experiences with other guy's bikes with the gearing change.I had a 43 and a 17 on my first 14R,Brocked it out,piped it...and had their flash in there as well.I never experienced a stumble......HOWEVER....that doesn't mean it couldn't be happening with gearing combos....like C said...it's all tied together....maybe my altitude here compensated for a possible stumble scenario....IDK....but with mine...the gearing somehow didn't affect the engine performance.....It was kinda fat down low..so maybe THAT prevented the stumble??????

It's a very intricately designed system...not like a KTRCless bike at all.

* Last updated by: Grn14 on 5/17/2014 @ 3:14 PM *

I have had the Stutter on my KTRC equipped bike.
Is KRTC and ABS an option in the US?
Bikes without it not affected by the 43 swap will prove it is the TRC ECU that is not happy.

My first suspicion was the TRC having issues with the gearing swap. This was the most logical.
I was of then given an opinion it is the way the maps rely on TPS and IAP and Gear Position for mapping at low RPM or throttle openings.
Getting the gear position out of kilter with a sprocket swap causes the map to switch into the injector pulse/setting either side of where it should actually be.
causing it to instantly go to rich causing the stutter from over fuelling.

Cblast filled in what I was trying to describe. Thank you.

"To solve this problem in the flash, the maps not just for fueling, but for ignition AND secondary throttle plates have to be unified not just across all cylinders but across all gears."

Cblast,

Do you do this with your flash?

My guess is a linear wave form. At a certain mph, there is a wave form, that if you remove your hands from the bars it shakes between a certain mph.

My guess is the ratio change is that change in window speed at that same certain "rpmph" speed: where the k-skid kicks in and shuts off that fast.

My guess is you might have to find more files that say k-skid: where is my tire diameter number to sprocket number maps so as to match the tone wheel speed fr to rr maps.

My guess would be you are still at the fuel/ign measuring file(s) and not in the skid-files. As is you are not in the ABS files.

My guess is there are hundreds of files that control this and that and if my guess is right, how could you control both an ABS and a k-skid map if you are at the ign/fuel/rpm/limiter/02/filtering/etc. maps.

Ok I been reading a lot on this. And it only seems to happen with the 43 toothed sprocket. So if you run a 40, 41, or 44 ect, or other there is no issue? Whether or not you use a 16, 17, 18 front sprocket? So what is the gearing change or unacceptable range in the ecu that may cause this issue? So one thing I will interject here thats different than what others have posted: I've put 23k miles on this bike In less than 18 months. Commute, backroad twisties, high speed runs., ect...cali bike, weather is 90% time good to ride.
0

I have noticed on my bike that when I'm hard in the throttle and I declarate quickly and get back into the throttle hard there is a stumble. Not all the time but every once in a while. Almost feels like I missed a gear shift or the bike is missing or sputtering, or the rear wheel is spinning, is the best way to explain it. Im running stock gearing . usually full power mode traction control set to 1 or off, Happened at stock ride height, lowered, lowered and stretched, and it seemed to happened in the 3k- 7k range the most Regradless of what gear im in. This has happened before and after I've had the ecu flashed. Maybe its just more pronounced because u feel it with gearing change.
Cause its more pronounced. ..IDK. just a thought.

how about...when you put on a 43..sprocket is bigger..wheel moves forward..sensor doesnt get good signal from speed ring on rear wheel...put stock back on ...wheel moves back...speed sensor gets good signal all is well...maybe,maybe not..just sayin

afterthought...if your chain is "stretched" issue may not appear... but a "new" chain is shorter...moving the wheel
even farther forward...ergo...some have issues some dont...just sayin

* Last updated by: wndsrfr on 5/19/2014 @ 6:28 AM *

Look at the sprocket diameter like a fulcrum point or pull. So if I drilled a hole at the top of the sprocket [just under the teeth], bolted an arm for that leverage, look at how fast I could turn the sprocket if it had a larger diameter. My larger sprocket would spin the windows faster than say a smaller [or the OE] sprocket: I pull the angle from 12 to 9 o'clock: who would move faster/sooner/travel farther>>> if I chained a box to the sprocket tooth right behind the lever and dragged that box from 12 to 9? The larger sprocket would.

So with a larger sprocket, wouldn't I get out of the hole faster with more teeth? Yes. Wouldn't my tone wheel move faster than a stock sprocket? Yes. Wouldn't that tone wheel be within that 'wobble zone' and then all is well? Just that tiny bit of fulcrum window [movement] is how fast the k-skid is 'setup or upset': is how you look at it.

My back wheel is churning up rocks and I'm spinning up the tach/speedo; where the front wheel is 'not matching tone wheel for tone wheel': until I hit the asphalt. Make sense yet trying to figure it out? I think I see it. You are on your own skill level and do not come back at me someone tells you to jump off a bridge and you do.

Take a hose and wet down the street with a long sweep as far as you can stand in one spot: is all you need in length. Now, from a dead stop just nail it on the wet stuff and keep your feed down for balance, or snap them up to the pegs if you are coordinated and have good balance. How fast did the k-skid kick in?

You'll never know that instant feel of the intervention as the wheel just ever so slightly looses traction, that tone wheel was way too fast against the front wheel's tone wheel. Feel it now? Because, I cannot describe how fast that system operates. One has to feel the package you are sitting on.

Cblast,
Do you do this with your flash?

Yes, absolutely.

I have noticed on my bike that when I'm hard in the throttle and I declarate quickly and get back into the throttle hard there is a stumble. Not all the time but every once in a while.

That is the whole system you more or less have interceded into. The wheelie over system and the k-skid system are like the same thing. You have X being the rpm and Y being the TPS. Y is in this range vs. where the rpm is going to head, k-skid more or less is going to detune that opening so the back does not come out skidding getting there or the front wheel comes up, we matched either combo.

1. Wheel spin
2. Normal accel
3. Wheelie
4. Bike leaps off the ground [drag race start]

Are we at 4 variables we cannot add another? So are there 4 ways to accelerate away? Unless I'm missing one.

So the final solution to the 43T rear sprocket issue is to have the ECU flashed with unified fuel/ignition maps? I'm about to install just a 43T rear sprocket on my 14R tomorrow and wanted to make sure that this is all that's needed to avoid the TRC stumble that I've read on this forum.

Thanks

I've learned that stock gives me not bit of glitch.
I shoot at the hip, so me slogan goes like dis...

Takes a man to live with a glitch.

Signed,
Stay Stock Club

Quick update-

I installed the 43T rear sprocket, still stock 17T front, and I've been riding it pretty much all day with no signs of stutter/sputter in any of the gears. After installing the rear sprocket I flashed my ECU with unified fuel/ignition maps for all cylinders and gears through Woolich . I never tried riding it without the maps being un-unified since I read beforehand that unifying the maps would fix any potential stuttering issue.

Hope this helps someone.

Thanks

i put a simple old TRE on that lock everything in 6th gear and solve mine 88cents

Back to state that the stuttering reared itself today out of nowhere. As mentioned multiple times by numerous of riders, it occurred in 1st and 2nd gears between 3K-5K RPM. Unifying ECU maps isn't a solution and from my extensive research there's no fix to this issue other than going for a different size rear sprocket or combining a 16T front sprocket along with the 43T rear sprocket.

IDK.I switched mine several times front and back with specific gearing in mind.It never did have that issue.And quite few 14nrs say they had t5his bucking issue.How's the chain adjustment?Throttle free play?Yeah.Mine was also flashed and had(I THINK)a PC5 mapped out by Brock's.It may not have been flashed.That was several years ago.

Computer bike tampering is like playing in Vegas. House is going to win most of the time.
1. Stock - Full Power - No stutter. The winner beats the house.
2. Sprocket - Full Power - Stutter. House wins.
3. Hack Job - Coded - 'we save engine' - Slow Power. House wins again.

However, your in luck. Here, try dis site: www.manupills.com. Take a 500mg pill before you suit up to ride. Please read label first it's a short list. Says causes severe flatulence. When that pill kicks in, it overrides exhaust pop, AND sprocket stumble like its not even there.

Signed,
Guaranteed or your money back

Grn14 I just went back to stock since it seems that there's no definite solution to the 43T sprocket sputtering issue, other than some say they didn't experience the issue with the 43T only sprocket installed. I was thinking of going 16 up front with the 43 rear...but my setup is stock wheelbase and I just don't need that much grunt down low where wheelies would be more prone when I get on it. I was just looking for a subtle change hence the reason why I tried the 43T rear sprocket.

Hub- I guess now that I've reverted back to stock gearing....I beat the House. :)

Don Guhl had a fix for the stutter after gearing change but he stopped flashing ECU's.
I'd call him and see if he will address what's causing the stutter.
Guhl Motors Shop. Phone : 717-618-4212
Hank