wby300
Novice Class
Posts: 43
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posted June 07, 2009 05:21 AM
Gear ratio to get correct speedo reading?
My 12 was off by about 10mph and I recently got indiglo guages for it, its a 2001 but I got the 2000 model guages and now its off by 15 at 60mph. Should I try to use sprockets to get it close to actual or will that place the gearing way too tall? I am comming up with 18/41 Also am I trying to figure this right? I am running 60 but the speedo says 75, rpm at 3800, so basically I am trying to get the bike moving the same speed as the speedo is reporting, Thing is I dont want gearing so tall I can only run at bonneville. Or s a speedo healer the route to go? I am using the gearing commander to figure this and overall it doesnt look on paper so to speak that it will change much on the low rpm/slow speed side, but magnifies as speed/rpm increase, much like the percentage the speedo is off. The 18/41 says it will make the actual speed 74.9, right at what I need, but I dont want the make the bike impossible to take off from lights in the city.
  
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Shane661
Needs a life
Posts: 11494
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posted June 07, 2009 06:45 AM
Get a speedohealer.
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wby300
Novice Class
Posts: 43
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posted June 07, 2009 12:40 PM
kind of what I fgured
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entropy
Moderator
Posts: 8671
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posted June 07, 2009 05:11 PM
18/44 will cause my 12's speedo to read very close to true mph (depending upon the r tire circumference)
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wby300
Novice Class
Posts: 43
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posted June 07, 2009 06:05 PM
Well I was just going off what the gearing commander says for the speed/rpm at the different ratio's. I know I am 15mph off at 60. So another question, an 18/46 gear set and a 16/41 are only .27% difference in rpm/mph, so is there a difference in the way the power gets delivered even though the ratio is very close? seems like leverage on a bigger or smaller front sprocket would have a bearing on the way the power gets from the engine to the ground.
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Shane661
Needs a life
Posts: 11494
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posted June 08, 2009 03:53 AM
The larger sprockets are easier on the chain, and probably a little more efficient.
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Tazio
Parking Attendant
Posts: 18
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posted June 08, 2009 01:15 PM
There's a speedo healer for $80.00 on Kawasaki World Forums. Raising your gearing that much would give you a 100 mph 1st gear and make the bike a dog to launch.
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Tazio
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wby300
Novice Class
Posts: 43
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posted June 08, 2009 01:17 PM
kind of what I was thinking
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wby300
Novice Class
Posts: 43
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posted June 08, 2009 01:43 PM
 Edited By: wby300 on 8 Jun 2009 21:44
So how much off was the 2000 zx12? My engine and gearing is all stock except airfilters and pipe, so after the gauge change its 15mph off at 60, was the 2000 model if the 2000 model wasnt off by that much, why? I know I am being ignorant on this, just trying to understand why these things are off by so much.
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thekaz
Needs a job
spell chequer is bustimicated
Posts: 2909
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posted June 08, 2009 04:08 PM
I used a speedo healer and GPS to correct my 2001 which was 23% incorrect with the stock face and then 27% with my 370KPH face.....
It was crazy easy but now with corrected speed and odometer I get really poor gas milage as compared to before 
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wby300
Novice Class
Posts: 43
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posted June 08, 2009 04:13 PM
well my fuel mileage isnt all that great, most of my riding is above 6k rpm other than highway. probably going to go with a speedo healer.
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shiphteey
Needs a job
Posts: 2529
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posted June 08, 2009 05:58 PM
quote:
18/44 will cause my 12's speedo to read very close to true mph (depending upon the r tire circumference)
+1. On a similar note I ran a 190/60 tire on a 2006 GSXR 1000...stock tire was 190/50. Speedo was pretty on....183 indicated was 182 on GPS....usually its off by a bit with a stock tire.
A.
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Gemini Motorcycles
Topping out everything from Ninja 250s to nitrous ZX-14s.
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wby300
Novice Class
Posts: 43
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posted June 09, 2009 01:07 AM
makes sense, if I could get to with in 5mph, I would be happy. Might do a little playing with the numbers on tire then too. Thanks for the thaught guys.
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wby300
Novice Class
Posts: 43
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posted June 09, 2009 09:01 AM
well the according to the numbers, if I use a 200/70/17 rear tire it will get me where I need to be on the actual speed matching the speedo, but is a 70 profile tire too much? I have looked and it seems most other bikes use a higher profile tire and even the zx12 uses a 70 on the front, why is that?
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shiphteey
Needs a job
Posts: 2529
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posted June 11, 2009 03:15 AM
You want to go from stock 200/50 to 200/70? Huge jump. I can send you a race takeoff 190/60 cheap if you want...200/70 just sounds a little ridiculous. Front and rear are vastly different. The "70" means 70 percent height...height in this case of 200mm....
Front is a 70 profile for a number of reasons, but remember its 70% the height of 120mm...not 200.
A.
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Gemini Motorcycles
Topping out everything from Ninja 250s to nitrous ZX-14s.
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wby300
Novice Class
Posts: 43
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posted June 11, 2009 03:25 AM
yea I cant find the 200/70 anyway. I think I am just going to do the speedo healer, I just really wanted a way to fix this without adding more stuff to the bike. I understand the tire profiles, but most tires are matched profile front and rear, I figure they did that so the higher profile narrower tire has a similar profile to the wider lower profile one. The tires now are pilot HPX and I dont really like them, the rear one seems to walk to the outside on curves, not slide out, it walks at low speeds on slight curves. That was another reason I considered a higher profile rear. how much for the tire and what kind of shape is it in?
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shiphteey
Needs a job
Posts: 2529
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posted June 11, 2009 07:03 AM
Tire is a "take-off" tire, meaning it was used on the track and then removed. It has some brief street usage (2000 ZX9R) before it was removed. Email me at novarockband@yahoo.com I can send you some pics. $50 shipped to the 48 states works.
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Gemini Motorcycles
Topping out everything from Ninja 250s to nitrous ZX-14s.
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2000redrocket
Pro
Posts: 1662
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posted June 21, 2009 06:23 PM
either way tire or sprockets you are going to end up with overall taller acting gearing. keep it the stock way and speedoheal it.
i bet the 2000 gets its speed reference different or the ecu sends a slightly different signel ratio to the speedo. it makes sence to me.
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Streetstretch
Novice Class
Posts: 45
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posted August 25, 2009 09:17 AM
speedo healer is the way to go, got one of ebay for like 120 real easy to hook up. You just go to the website and plug in the gears teeth that you have and it tells you the percentage you need to change it to.
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EastBayDave
Needs a job
Posts: 2245
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posted September 01, 2009 11:51 AM
you gotta keep the 220mph speedo, no matter what. 
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Enjoy the ride!
02' ZRX1200
00' ZX12R sold
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wby300
Novice Class
Posts: 43
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posted September 01, 2009 03:14 PM
well I got the 220 speedo, not getting rid of it now, I just know that at 60 I am doing 45 and at 75 I am running 60. Nothing else matters because anything over 60 is all illegal in Indiana, unless your on the interstate, then its 70.
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