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Sprocket Mods - Effect on Speed

6930 Views 35 Replies 11 Participants Last post by  Jester
Okay guys here's the deal:

This spreadsheet will determine how fast the bike will go at what speed based on sprocket size.

I have the stock numbers plugged in to start.

This should help Darkhorse especially because he's racing his.

Download link: http://rapidshare.com/files/156003360/Gear_Calculator.xls.html

It seems to be accurate. With the stock configuration plugged in, it says the bike'll go 105 @13000 rpm. Which seems right based on what I've heard.
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Note: This was made by an administrator of landracing.com. The download link above has stock sprocket configuration and wheel diameter plugged in.

original thread: http://www.landracing.com/forum/index.php/topic,3719.0.html
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With the stock configuration do you mean 14 /45? I have only seen 97 mph out of a stock bike. that might have to do with the engine not reaching the 13000rpe limiter though. With a head wind or when I over gear it the the engine sits at 11500 rpm. that is the top of the power band.
How come you guys bike's stock configuration is 14/45 while mine over here is 14/43? I had changed mine from 14 to 15 and the difference in RPM at 100km/hr is app. 500rpm which is now at 6500rpm. Am thinking of going to 42 at the back to further lower the rpm for a more quiet and relaxed ride on the highways... What are your views on this?.... Cheers
Would you not lose top end for doing that? Would the only benefit be lower RPMs? If so, I might do it since it would also give better MPG.
bigger the sproket better accel but lose top end, plus its easier to stunt with a bigger sprocket.... my buddy has a f4 and he stunts for the thing he has done to his bike it would kill me but his sproket is so big his top speed is like 110-120 mph hahaha when we go on the highways we all dust him going past 150 easy, but once we are at the stunt spot we kills us easy wheelies and what not. and your speedo changes too when you switch out the sproket to bigger or smaller it may saying your going like 80 but really your going like 65 or 70 so gotta watch out fot that
You gotta watch for when your doing 85 and it says 65! haha
Officer I swear, I was only going 65 man! What's that? Your speedo isn't accurate? TICKET! As long as you don't say anything when you get pulled over your fine!
hahaahaha


yeah man if you change your sprocket make sure you ride with the flow of traffic, or just go to somplace where they can fix your speedo, its not like you can "speed" on a ninja 250r anyways hahaha im just kidding!....angy mob of 250r owners piling on top of me....
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Wow, I'm sure they had a good laugh at that one!
The speedo is driven off the front wheel, gearing makes no diff, unless you do the front-wheel-drive conversion.
well i guess thats on ninjas then because on everyone else that i know their speed is off because of their sprokets esp stuners with their huge sprokets makes a big diff in speed trust me... only canles i see on the front tire is break line... and if it went off the front tire when you do whillies it would say 0 miles an hour how can you ride at 0 mph hahaha
i concur. R6 is probably right. But I don't have a bike so I am not sure.
thanks jester! hahaha psh i cant even wheelie but im sure all bikes are made the same way you know, and the 250r only has one wire because it only has one break...is the other wire invisable? front tire only rolls with the bike just like a push bike what makes the bike go is the rear so im pretty sure it reads off the rear tire axle or chain or sproket so if anything is changed from the stock your gonna get different readings that for sure! but then again i dont own a 250r so i could be wrong but im pretty sure of what im saying
R6S_2NR said:
thanks jester! hahaha psh i cant even wheelie but im sure all bikes are made the same way you know, and the 250r only has one wire because it only has one break...is the other wire invisable? front tire only rolls with the bike just like a push bike what makes the bike go is the rear so im pretty sure it reads off the rear tire axle or chain or sproket so if anything is changed from the stock your gonna get different readings that for sure! but then again i dont own a 250r so i could be wrong but im pretty sure of what im saying
Why post info when you do not know anything about the Ninja 250R? The speedometer is driven off the FRONT tire the cable is on the left side of the bike. See it in this photo?
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No info = no knowlege = no post.

You are right on KEN.
are you sure that that cable is for that and not just another little detail to make the big look biger like kawi intended to? hahaha im jk! thats why i said maybe ninja 250r are different but you guys are right, thats even better can change the sproket and not worry about your spedo changing on you, i had right info just got for the 25, but do you really think that having it in the front gives you acurate speed reading?
dude it doesn't make any difference at all ahahaha both wheels go the same speed.
assuming that they're the same diamter. which they are.
no way dude one wheel has to go faster right? you would the thr rear because its pushing it with the chain...this is like rocket science dude
I'm going to assume that wasn't being sarcastic. If it was, don't read past this sentence.

With the exception of burnouts, if both wheels are touching the pavement, they are going the same speed.

if anything, the front wheel goes a tiny bit faster in the turn, but not much. and really only low speed turns are affected.

There's no physical way one wheel could be going a different speed than the other.
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