progger
Parking Attendant
Posts: 7
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posted August 31, 2011 10:00 AM
42 tooth rear sprocket
I am wanting a small gearing change for the street, and believe the 42 tooth rear sprocket to be what I need. I want to maintain the abilitiy to reach top speed.
Can someone tell me what this small change will do to the speedo reading? It's my understanding that it reads 5 to 7% high from the OEM?
Would I still need a speedohealer for such a small change in the rear?
Thanks in advance.
  
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joel787
Zone Head
Posts: 590
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posted August 31, 2011 10:43 AM
Stock is 41 if u go to a 42 honestly it would be Waste of money, get a 16t front it would be cheaper
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TH1RT3EN
Zone Head
Trial And Error Control
Posts: 722
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posted August 31, 2011 01:04 PM
personally i would get a speedo healer anyway. it makes it much easier to swap anything around.
And i agree with the 16T front being a better choice.
Patrick
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There is a fine line between Fear and Respect
When I was a kid i used to........... Wait I Still Do That!
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Wheelie
Needs a life
Old Man
Posts: 6902
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posted August 31, 2011 01:05 PM
quote:
Stock is 41 if u go to a 42 honestly it would be Waste of money, get a 16t front it would be cheaper
what he said ^
wee
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Audioboyz
Expert Class
Posts: 265
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posted August 31, 2011 01:13 PM
I have 16/43 combo.I like that with my Brocks pipe,not worried about topend since I never saw it anyway with these terrible roads in Pa.Have the speedohealer also.It's off by about 4 mph after I went to a 55 profile rear tire.
Craig
____________
2009 Monster ZX-14
Brocks Alienhead,PCV, flys out,LSL Riser kit,-1 front sprocket,43 Vortex rear sprocket,K&N Air Filter, Zero Gravity tall smoked screen,block off plates,175HP 104 torque
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kaw now
Expert Class
Posts: 446
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posted August 31, 2011 04:30 PM
I think my speedo is closer to 8% off factory. Good point though on the bigger back gear if you're getting a new chain. I think I'd go two teeth leave 17 in front for a bigger radius easier on chain.
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ryn0cer0s
Expert Class
Rider for Life
Posts: 274
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posted August 31, 2011 04:56 PM
First of all, all bikes come with a speedometer error. A SpeedoHealer can correct that. Going to a 42 would get you closer to the actual reading on your speedometer. If you want to see what gearing changes will do to your top speed, check out this site:
http://www.gearingcommander.com/
____________
RYNO
2010 Candy Persimmon Red ZX-14
Brock's Ceramic coated Alien Head full exhaust
PCV, SpeedoHealer, lowered
"Never ride faster than your guardian angel can fly"
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Wheelie
Needs a life
Old Man
Posts: 6902
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posted August 31, 2011 05:10 PM
quote:
First of all, all bikes come with a speedometer error. A SpeedoHealer can correct that. Going to a 42 would get you closer to the actual reading on your speedometer. If you want to see what gearing changes will do to your top speed, check out this site:
http://www.gearingcommander.com/
wouldn't a larger rear sprocket make the speedo read faster?
wee
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Audioboyz
Expert Class
Posts: 265
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posted August 31, 2011 05:26 PM
Yes it would because the sensor would read high.I remember when I did my sprockets it was like 17% high.A GPS and speedo healer fixed that.It adds miles to your bike too.I got to adjust mine again after I got a 190/55/17 tire.It's like 4 MPH off at 100 MPH on the gearing commander site.
Craig
____________
2009 Monster ZX-14
Brocks Alienhead,PCV, flys out,LSL Riser kit,-1 front sprocket,43 Vortex rear sprocket,K&N Air Filter, Zero Gravity tall smoked screen,block off plates,175HP 104 torque
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zixxer14
Pro
Damn that was Quick
Posts: 1233
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posted August 31, 2011 07:25 PM
I'm running a 42 on the rear & like it better than the 41, not racing it but it works a bit better around town & doesn't jump up the revs too much on the highway. I believe I compensated about 16% on my speedohealer using a gps as a reference with this gearing. I don't remember if the new chain was longer or not, if it was it was only 1 link longer. Got it from Drive Systems, give them a call & they can tell you if you need to extend the chain any.
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zixxer14
Pro
Damn that was Quick
Posts: 1233
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posted August 31, 2011 07:26 PM
I'm running a 42 on the rear & like it better than the 41, not racing it but it works a bit better around town & doesn't jump up the revs too much on the highway. I believe I compensated about 16% on my speedohealer using a gps as a reference with this gearing. I don't remember if the new chain was longer or not, if it was it was only 1 link longer. Got it from Drive Systems, give them a call & they can tell you if you need to extend the chain any.
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Audioboyz
Expert Class
Posts: 265
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posted August 31, 2011 07:40 PM
If you run 16/43 you can use the stock chain.I'm so used to it don't know what I would do without it.I had a ZRX1100 and I went from 17/45 to 17/49.That bike would wheelie and top end was better do to the mechanical advantage.
Craig
____________
2009 Monster ZX-14
Brocks Alienhead,PCV, flys out,LSL Riser kit,-1 front sprocket,43 Vortex rear sprocket,K&N Air Filter, Zero Gravity tall smoked screen,block off plates,175HP 104 torque
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progger
Parking Attendant
Posts: 7
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posted August 31, 2011 09:07 PM
New bike..Just hit 500 mi/first oil change. Will be better able to gauge what I want once the M 14 and PC are on.
Audio, live in N Texas; not many corners here, lots of straight, flat two lane country roads. Looking for the "mechanical advantage" you speak of, without running out of revs before I hit the 186 limiter. Ideally, I'd want to be close to redline at that speed, no? The 16/43 seems ideal for drag racing, but a lot steeper than what I'm looking for.
Zixxer14, I was looking at the Drive systems steel 42. If I go that way, hope a new chain is not nec once it gets a little stretch. Thanks again.
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ryn0cer0s
Expert Class
Rider for Life
Posts: 274
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posted August 31, 2011 10:15 PM
quote:
quote:
First of all, all bikes come with a speedometer error. A SpeedoHealer can correct that. Going to a 42 would get you closer to the actual reading on your speedometer. If you want to see what gearing changes will do to your top speed, check out this site:
http://www.gearingcommander.com/
wouldn't a larger rear sprocket make the speedo read faster?
wee
The speedometer reads the speed at the front shaft (yes, I know it is actually the nut, but the effect is the same). One revolution equals 17 teeth. This tranfers to 41 teeth in the back. The ratio is 2.41. With 17 front and 42 back, the ratio is 2.47. In other words, it takes 2.47 revolutions of the front sprocket to make the rear wheel turn once. If you increase the number of teeth in the back, you will slow down the bike at the same RPM; the front sprocket has to turn further (faster) to get the same speed out of the wheel.
Since the speedometer is already about 5% high (at least on my bike), you could go up about 2-3 teeth in the back and still be closer to the actual speed of the bike. 1 tooth is roughly a 2% change.
____________
RYNO
2010 Candy Persimmon Red ZX-14
Brock's Ceramic coated Alien Head full exhaust
PCV, SpeedoHealer, lowered
"Never ride faster than your guardian angel can fly"
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kaw now
Expert Class
Posts: 446
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posted September 01, 2011 11:29 AM
Your thinking is in reverse bike slows down for engine rpm = rpm speed up for bike speed and sensor is on engine = faster speedo reading.
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Wheelie
Needs a life
Old Man
Posts: 6902
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posted September 01, 2011 11:52 AM
quote:
quote:
quote:
First of all, all bikes come with a speedometer error. A SpeedoHealer can correct that. Going to a 42 would get you closer to the actual reading on your speedometer. If you want to see what gearing changes will do to your top speed, check out this site:
http://www.gearingcommander.com/
wouldn't a larger rear sprocket make the speedo read faster?
wee
The speedometer reads the speed at the front shaft (yes, I know it is actually the nut, but the effect is the same). One revolution equals 17 teeth. This tranfers to 41 teeth in the back. The ratio is 2.41. With 17 front and 42 back, the ratio is 2.47. In other words, it takes 2.47 revolutions of the front sprocket to make the rear wheel turn once. If you increase the number of teeth in the back, you will slow down the bike at the same RPM; the front sprocket has to turn further (faster) to get the same speed out of the wheel.
Since the speedometer is already about 5% high (at least on my bike), you could go up about 2-3 teeth in the back and still be closer to the actual speed of the bike. 1 tooth is roughly a 2% change.
what? lol
wee
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Wheelie
Needs a life
Old Man
Posts: 6902
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posted September 01, 2011 12:22 PM
quote:
quote:
quote:
First of all, all bikes come with a speedometer error. A SpeedoHealer can correct that. Going to a 42 would get you closer to the actual reading on your speedometer. If you want to see what gearing changes will do to your top speed, check out this site:
http://www.gearingcommander.com/
wouldn't a larger rear sprocket make the speedo read faster?
wee
The speedometer reads the speed at the front shaft (yes, I know it is actually the nut, but the effect is the same). One revolution equals 17 teeth. This tranfers to 41 teeth in the back. The ratio is 2.41. With 17 front and 42 back, the ratio is 2.47. In other words, it takes 2.47 revolutions of the front sprocket to make the rear wheel turn once. If you increase the number of teeth in the back, you will slow down the bike at the same RPM; the front sprocket has to turn further (faster) to get the same speed out of the wheel.
Since the speedometer is already about 5% high (at least on my bike), you could go up about 2-3 teeth in the back and still be closer to the actual speed of the bike. 1 tooth is roughly a 2% change.
got it, I should have put a 34t on the rear instead of a 48t. Will do on my 2012. Thanks
wee
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Audioboyz
Expert Class
Posts: 265
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posted September 01, 2011 12:25 PM
Progger
If you ran a 16 front and a 43 back with a 55 series tire and had it set with the Speedohealer and GPS heres what you would have.The gearing commander says at 10600 RPM the speed would be 185.I don't think it would pull 11000 but I'll never know since theres only an interstate to try this on and I don't want to loose my license.I pluged in the top speed wire ino my Speedohealer.It read 140 so I know I hit 165 once.So It must of been before I installed the Healer.
Craig
____________
2009 Monster ZX-14
Brocks Alienhead,PCV, flys out,LSL Riser kit,-1 front sprocket,43 Vortex rear sprocket,K&N Air Filter, Zero Gravity tall smoked screen,block off plates,175HP 104 torque
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ryn0cer0s
Expert Class
Rider for Life
Posts: 274
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posted September 01, 2011 12:57 PM
 Edited By: ryn0cer0s on 1 Sep 2011 21:00
quote:
quote:
quote:
quote:
First of all, all bikes come with a speedometer error. A SpeedoHealer can correct that. Going to a 42 would get you closer to the actual reading on your speedometer. If you want to see what gearing changes will do to your top speed, check out this site:
http://www.gearingcommander.com/
wouldn't a larger rear sprocket make the speedo read faster?
wee
The speedometer reads the speed at the front shaft (yes, I know it is actually the nut, but the effect is the same). One revolution equals 17 teeth. This tranfers to 41 teeth in the back. The ratio is 2.41. With 17 front and 42 back, the ratio is 2.47. In other words, it takes 2.47 revolutions of the front sprocket to make the rear wheel turn once. If you increase the number of teeth in the back, you will slow down the bike at the same RPM; the front sprocket has to turn further (faster) to get the same speed out of the wheel.
Since the speedometer is already about 5% high (at least on my bike), you could go up about 2-3 teeth in the back and still be closer to the actual speed of the bike. 1 tooth is roughly a 2% change.
got it, I should have put a 34t on the rear instead of a 48t. Will do on my 2012. Thanks
wee
Thanks Wee, bad wording on my part. the 48t would indeed make your bike accelerate faster, but (this is what I meant) would give you a lower top speed. You would get to the rev limiter at a lower speed. My understanding of what Progger was looking for was to NOT lower his top speed.
I guess I should watch how I word things more carefully. Thank you for pointing out the incongruity of my statement.
____________
RYNO
2010 Candy Persimmon Red ZX-14
Brock's Ceramic coated Alien Head full exhaust
PCV, SpeedoHealer, lowered
"Never ride faster than your guardian angel can fly"
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BLK ICE
Pro
we'll leave the light on for u
Posts: 1709
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posted September 01, 2011 01:04 PM
Edited By: BLK ICE on 1 Sep 2011 21:08
I topped out 6th gear last weekend with 16/51 with 180/55 @ 150mph, speedhealer -30.8%. Fun!
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