[Duckman]

I know it’s all been said before but this whole issue makes no since at all to me. The gear indicator going - - especially. Gear position isn’t calculated. It’s a physical switch. As long as the bike is powered up it knows the gear position no matter what. Even on ABS models the only thing really needed is wheel speed and there’s two sensors for that. And ABS also works no matter what gear your in, even neutral, at any speed over about 5 mph or so. What any of this has to do with final drive gear ratios is beyond me.

 

[Banjoboy]

I know it’s all been said before but this whole issue makes no since at all to me. The gear indicator going - - especially. Gear position isn’t calculated. It’s a physical switch. As long as the bike is powered up it knows the gear position no matter what. Even on ABS models the only thing really needed is wheel speed and there’s two sensors for that. And ABS also works no matter what gear your in, even neutral, at any speed over about 5 mph or so. What any of this has to do with final drive gear ratios is beyond me.

It's ll down to garbage ECU programming. For whatever reason, Kawasaki has the ECU programmed to read rear wheel speed, and when gearing is changed, the ECU gets confused, (Ever ask a blonde girl what time it is?) and starts do'in stupid stuff. Since changing the gear ratios is very common, Kawasaki should fix their ECU. You can change gearing on any other manufacturer's bike, and not have this problem.

 

[Teorist]

This is one reason why, as a software developper, I think that we overuse software. I know that there are advantages to using software but there is a price that comes with a more complex system.

 

[Craig H]

I know it’s all been said before but this whole issue makes no since at all to me. The gear indicator going - - especially. Gear position isn’t calculated. It’s a physical switch.

I am SO with you on this. Furthermore, if they feel the need to also code a software window for some silly reason, it's crazy that there's no way to recalibrate it when you change gearing -- which is something very commonly done. And the 7% window is obviously not important, since everything works just fine when you bypass the clutch lever sensor.

Bad job Kawasaki software people, bad job.

 

[BenTexas]

Gearing Commander - Motorcycle Speed and Drive Train Calculator v7 The Final Word!

 

[Jim G]

Does changing the sprocket ratio by more than about 7% also have any adverse effect on the ABS system, or not? Just asking because if the change affects the CEL and gear ratio displaym, who knows what else it might affect.

Jim G

 

[Craig H]

Does changing the sprocket ratio by more than about 7% also have any adverse effect on the ABS system, or not? Just asking because if the change affects the CEL and gear ratio displaym, who knows what else it might affect.

Jim G

I can't say for sure because I haven't done anything that might activate it, but it seems very unlikely because a perceived ABS problem would certainly throw a code.

 

[Tracy]

I believe that different bikes react differently to the +7% change. Duckman stated no errors of any kind. Banjoboy stated no loss of ABS. My bike lost gear indicator, engine light, and loss of ABS with no indication on the dash. I frequently activate the ABS to make sure it works and so I'll know haw the Z is gonna react...always on a known slick surface
ZZ

 

[Duckman]

I believe that different bikes react differently to the +7% change. Duckman stated no errors of any kind. Banjoboy stated no loss of ABS. My bike lost gear indicator, engine light, and loss of ABS with no indication on the dash. I frequently activate the ABS to make sure it works and so I'll know haw the Z is gonna react...always on a known slick surface
ZZ

Hey Tracy, next time you’re out try this. Get up to your test speed, shift the bike back into neutral with clutch out. At this point the bike has no way of possibly knowing what sprockets you’re running. Does ABS still work?

 

[Tracy]

Well I changed my sprockets back to <7% difference so I can't try that. I always did it in gear,clutch in
ZZ

 

[Craig H]

I believe that different bikes react differently to the +7% change.

Jeez, that makes this whole fiasco even more ridiculous. I sure hope they fix it in the next generation -- and by "fix" I mean just delete the crappy code.

 

[Duckman]

Well I changed my sprockets back to <7% difference so I can't try that. I always did it in gear,clutch in
ZZ

Then you're just going to have to trust me. It will still work no matter what gearing you're using. I just thought you would be a good test candidate since you are not afraid to actually trigger the ABS.

 

[Tracy]

Afraid? He!! I do it all the time
ZZ

 

[Jim G]

Well THAT was a vigorous discussion on the ABS situation! Glad I asked!

Jim G

 

[Matt7635]

Finally got my chain & sprocket swapped tonight and got home . +3 in the rear. The bike definitely felt smoother with that kinked up chain gone, and acceleration felt a tad faster (i think)… if i had the tools or if my mechanic wasnt 40 minutes away, i kind of want to try throwing on the -1 front i have laying in my closet too. If I did, that would theoretically be a 14% change giving me a top speed of 109 mph. I think i would be okay with that as i rarely spend much time up at that speed, and when im riding spiritedly with ppl, once we get to those speeds, it’s not like that extra 18 mph will help me catchup to my buddies with liter bikes. It’s hard for the bike to even chug up to those speeds with the inclines here anyways. That extra acceleration oomph will help me make the gap wider, or close the gap where it counts. But I dont go to the canyons much anymore, and the two i like dont really have long straights, and the one place it does, theres a very steep incline so that new gearing will actually help me get to a faster speed.

i also may be interpreting how gearing works wrong. And also these numbers are based off gearing & speed calculations ive seen in other threads here. Stating top speed of 127 mph at 12k rpm. Not sure if that is indicated or actual speed.

 

[Rich T]

127 is theoretical top speed if you can actually pull to 12,000 rpm in 6th and your tire circumference is exactly what is on the label (i.e., pi * d, where d is rim size in inches + 2x the tire height, which is the tire width in mm times the profile percentage).

I'm pretty sure the speedometer and tachometer will say something else (mine are off by 5%, optimistic).

You can run thru the calculations yourself trivially for the stock final gear ratio of 2.929 (i.e., 41/14) and stock tire size 150/60-17 (you can click the link below and play with the numbers):

primary = 2.219 & gear6 = 1.037 & final = 2.929 & radius = 17 inch/2 + 150 mm*60% & 12000 rpm*2pi/primary/gear6/final * radius ? mph primary = 2.219 > 2.219 defined gear6 = 1.037 > 1.037 defined final = 2.929 > 2.929 defined radius = 17 inch/2 + 150 mm*60% > (17 inch / 2) + (150 milli~meter * 60 percent) defined 12000 rpm*2pi/primary/gear6/final * radius ? mph > (((12000 rpm_as_frequency * 2 pi / primary) / gear6) / final) * radius ? mph = 127.581 mph

That's basically exactly what websites like www.gearingcommander.com do -- they just use the tire circumference, all theoretical. (Not taking into account tire slip, sag, wear, inflation, etc.)

If you change final to 3.143 (for +3, i.e., 44/14), above, your speed drops to 118.895 mph.

 

[Matt7635]

127 is theoretical top speed if you can actually pull to 12,000 rpm in 6th and your tire circumference is exactly what is on the label (i.e., pi * d, where d is rim size in inches + 2x the tire height, which is the tire width in mm times the profile percentage).

I'm pretty sure the speedometer and tachometer will say something else (mine are off by 5%, optimistic).

You can run thru the calculations yourself trivially for the stock final gear ratio of 2.929 (i.e., 41/14) and stock tire size 150/60-17 (you can click the link below and play with the numbers):

primary = 2.219 & gear6 = 1.037 & final = 2.929 & radius = 17 inch/2 + 150 mm*60% & 12000 rpm*2pi/primary/gear6/final * radius ? mph primary = 2.219 > 2.219 defined gear6 = 1.037 > 1.037 defined final = 2.929 > 2.929 defined radius = 17 inch/2 + 150 mm*60% > (17 inch / 2) + (150 milli~meter * 60 percent) defined 12000 rpm*2pi/primary/gear6/final * radius ? mph > (((12000 rpm_as_frequency * 2 pi / primary) / gear6) / final) * radius ? mph = 127.581 mph

That's basically exactly what websites like www.gearingcommander.com do -- they just use the tire circumference, all theoretical. (Not taking into account tire slip, wear, inflation, etc.)

If you change final to 3.143 (for +3, i.e., 44/14), above, your speed drops to 118.895 mph.

To clarify, i meant change the -1 front in addition to my +3 rear to equal 109 top. Used the app and i was one mph off - theoretically 110 on the site.
I also retract my statement, i think +3ish is a sweet spot. Remembered theres one sweeper i frequent on my morning commute where i hit 114 in average and the bike just doesnt want to pull much at that point. It doesnt feel that fast so having 109 as the cap would be kind of a bummer. Of course i know the risk and only do that when the road is empty; it’s a long sweeper that you can scope out early, big run off shoulders on both sides & at 7 am, it’s always empty

 

[Matt7635]

Update: second time on the bike, first commute to work. Confirmed 118 mph top speed at red. I was leaned over a bit so i couldnt tell exactly what the rpm was but the needle was red. It sat there for half a second WOT, but the incline started so it dropped to 114.
Love how smooth the bike feels now. Feels like it just cuts through the wind.
Makes me kind of want to start the mod bug… i must resist.

 

[JFMNINJA400]

I went with a new chain and +2 rear Driven aluminum rear sprocket. No issues with the gear indicator!!! I was already +1 rear and I can feel a slight difference. It pulls harder out of the corners. Did a trackday this past weekend at a very technical track, which is perfect for small bikes. I will be doing a track in the beginning of October where I will be able to see if there is any difference in the top speed.

 

[Matt7635]

I went with a new chain and +2 rear Driven aluminum rear sprocket. No issues with the gear indicator!!! I was already +1 rear and I can feel a slight difference. It pulls harder out of the corners. Did a trackday this past weekend at a very technical track, which is perfect for small bikes. I will be doing a track in the beginning of October where I will be able to see if there is any difference in the top speed.

I was contemplating the aluminum sprockets, but the mechanic heavily disagrees with them on street bikes. Says it'll get eaten up much quicker than the chains life, and not worth the few grams you'll save. I'm a little skeptical about that on our small displacement bikes... Also curious how a lighter sprocket would feel, although since I did two other modifications, I wouldn't be able to tell how much it contributed.
Ah you're one of the lucky ones! My mechanic said that all the bikes, and a few 400s that he's done gearing changes to, never had the issue I was describing. I didn't want to deal with the potential CEL issue and clearing it, so I just preemptively did the clutch jump wire trick. I'm fairly confident that safety mechanism won't come in handy for my process. I always start the bike in neutral and kickstand down, the kickstand safety switch still works and won't let the bike start in gear (tested).
Have fun at the track! I finally shelled out big money to fix the GTI I just bought, so I'm more confident in its towing ability. After I get a few other ducks in a row, i'll shell out the $450ish USD to throw a hitch on it. Then it's track time!