Sprocket Change

W.Roworth · October 31st, 2012, 06:00 PM

Im looking at slightly increasing the length of my gearing ratio and have heard a sprocket change is the best method....

I am completely in the dark about it though and need advice. Do I change front or rear? What amount of teeth would be best and what changes would occur?

Alex · October 31st, 2012, 06:14 PM

Info in this thread:

DIY- Sprocket Swap

It's just math. The taller the gearing, the lower the engine revs at the same road speed. The shorter the gearing, the higher the engine revs at the same road speed. To go taller, you add teeth to the front sprocket, or subtract teeth from the rear sprocket. To go shorter, you subtract teeth from the front sprocket, or add teeth to the rear sprocket. To figure out how much of a change it would make, just find the ratio between front/rear for both setups, and compare. www.gearingcommander.com lets you plug in all sorts of parameters, and shows you the exact differences you will see in revs and/or speed.

Most people who do change sprockets on the ninjette go taller on the gearing to make the bike slightly calmer on the highway (less revs). Easiest way to do this is to swap out the front 14-tooth sprocket with a replacement 15-tooth sprocket.

There are a ton of threads that basically say exactly this, in many different ways. Search for threads with "sprocket" in the title, and there's more reading material than even the most ardent sprocket specialist needs.

W.Roworth · October 31st, 2012, 10:54 PM

call me lazy but how many teeth are on the rear cog? what kind of revs would adding one tooth to the front change at 110kph? Im lookin to hear from people who have done it and what they think of the change.

Alex · November 1st, 2012, 06:22 AM

You're lazy.

psych0hans · November 1st, 2012, 06:38 AM

Quote:

Originally Posted by Alex

You're lazy.

flynjay · November 1st, 2012, 07:15 AM

Quote:

Originally Posted by W.Roworth

call me lazy but how many teeth are on the rear cog? what kind of revs would adding one tooth to the front change at 110kph? Im lookin to hear from people who have done it and what they think of the change.

15 tooth front sprocket is about 1000 rpm lower in pretty much any gear. 5th gear is like the old 6th gear.

Alex · November 1st, 2012, 10:46 AM

It's not quite that significant. It changes it by 14/15ths, exactly as one would expect. If it was at 15000 rpm, it would be at 14000 rpm after the change for a 1000 rpm drop. But if it was at 9000 rpm, a more typical highway cruising range, it goes down to about 8400 rpm. From 6000 rpm, it would drop to 5600. If the tach makes it look like it's dropping more, it's just a representation of tach inaccuracy. Gearingcommander is a particularly useful site to play with all of these numbers very quickly as you propose different sprocket sizes; no muss / no fuss.

az3200 · November 4th, 2012, 04:28 PM

so i'm a noob, but if you're cruising on the highway and swapped the front sprocket for the 15 tooth, and are at about 1000rpm less....about how much faster will the top speed of the bike be? 10mph or so?

choneofakind · November 4th, 2012, 05:01 PM

Quote:

Originally Posted by az3200

how much faster will the top speed of the bike be? 10mph or so?

maybe 1. You're still making a whopping 26 hp. The only change made by gearing changes is how fast you'll be going when you get to the power band.

ChaoSS · November 4th, 2012, 08:32 PM

You will change the theoretical top speed, the speed at which the bike would go if you could redline it in 6th, but that is not real world.

My bike hasn't gone over about 94 indicated (on mine that's going to be just a hair over 90 actual speed) and that was no redline. Now, i'm a big guy, and I have saddle bags that add to the wind reaistance, and really hadn't perfected my tuck. That being said I wouldn't excpect much more out of a stock ninjette.

I have a 15 tooth front on mine, for highway driving, keeps the rpms down a bit, and i'm thinking about a smaller rear, or a bigger tire. It isn't really like being in the next higher gear but when I first did it it did feel that,way

flynjay · November 5th, 2012, 08:03 PM

Quote:

Originally Posted by az3200

so i'm a noob, but if you're cruising on the highway and swapped the front sprocket for the 15 tooth, and are at about 1000rpm less....about how much faster will the top speed of the bike be? 10mph or so?

If our bikes were gearing limited, yes the top speed would increase. But, alas we are power limited.

October 31st, 2012, 06:00 PM	#1
W.Roworth ninjette.org member Name: Wayne Location: Bunbury Join Date: Aug 2012 Motorcycle(s): 2012 Ninja 250R Posts: 27	Sprocket Change Im looking at slightly increasing the length of my gearing ratio and have heard a sprocket change is the best method.... I am completely in the dark about it though and need advice. Do I change front or rear? What amount of teeth would be best and what changes would occur? __________________________________________________ Carpe Diem, then the throttle

October 31st, 2012, 06:14 PM	#2
Alex ninjette.org dude Name: 1 guess :-) Location: SF Bay Area Join Date: Jun 2008 Motorcycle(s): '13 Ninja 300 (white, the fastest color!), '13 R1200RT, '14 CRF250L, '12 TT-R125LE Posts: Too much. Blog Entries: 7	Info in this thread: DIY- Sprocket Swap It's just math. The taller the gearing, the lower the engine revs at the same road speed. The shorter the gearing, the higher the engine revs at the same road speed. To go taller, you add teeth to the front sprocket, or subtract teeth from the rear sprocket. To go shorter, you subtract teeth from the front sprocket, or add teeth to the rear sprocket. To figure out how much of a change it would make, just find the ratio between front/rear for both setups, and compare. www.gearingcommander.com lets you plug in all sorts of parameters, and shows you the exact differences you will see in revs and/or speed. Most people who do change sprockets on the ninjette go taller on the gearing to make the bike slightly calmer on the highway (less revs). Easiest way to do this is to swap out the front 14-tooth sprocket with a replacement 15-tooth sprocket. There are a ton of threads that basically say exactly this, in many different ways. Search for threads with "sprocket" in the title, and there's more reading material than even the most ardent sprocket specialist needs. __________________________________________________ Montgomery Street Motorcycle Club / cal24.com / crf250l.org / ninjette.org ninjette.org Terms of Service Shopping for motorcycle parts or equipment? Come here first. The friendliest Ninja 250R/300/400 forum on the internet! (especially Unregistered)

October 31st, 2012, 10:54 PM	#3
W.Roworth ninjette.org member Name: Wayne Location: Bunbury Join Date: Aug 2012 Motorcycle(s): 2012 Ninja 250R Posts: 27	call me lazy but how many teeth are on the rear cog? what kind of revs would adding one tooth to the front change at 110kph? Im lookin to hear from people who have done it and what they think of the change. __________________________________________________ Carpe Diem, then the throttle

November 1st, 2012, 06:22 AM	#4
Alex ninjette.org dude Name: 1 guess :-) Location: SF Bay Area Join Date: Jun 2008 Motorcycle(s): '13 Ninja 300 (white, the fastest color!), '13 R1200RT, '14 CRF250L, '12 TT-R125LE Posts: Too much. Blog Entries: 7	You're lazy. __________________________________________________ Montgomery Street Motorcycle Club / cal24.com / crf250l.org / ninjette.org ninjette.org Terms of Service Shopping for motorcycle parts or equipment? Come here first. The friendliest Ninja 250R/300/400 forum on the internet! (especially Unregistered)

November 1st, 2012, 10:46 AM	#7
Alex ninjette.org dude Name: 1 guess :-) Location: SF Bay Area Join Date: Jun 2008 Motorcycle(s): '13 Ninja 300 (white, the fastest color!), '13 R1200RT, '14 CRF250L, '12 TT-R125LE Posts: Too much. Blog Entries: 7	It's not quite that significant. It changes it by 14/15ths, exactly as one would expect. If it was at 15000 rpm, it would be at 14000 rpm after the change for a 1000 rpm drop. But if it was at 9000 rpm, a more typical highway cruising range, it goes down to about 8400 rpm. From 6000 rpm, it would drop to 5600. If the tach makes it look like it's dropping more, it's just a representation of tach inaccuracy. Gearingcommander is a particularly useful site to play with all of these numbers very quickly as you propose different sprocket sizes; no muss / no fuss. __________________________________________________ Montgomery Street Motorcycle Club / cal24.com / crf250l.org / ninjette.org ninjette.org Terms of Service Shopping for motorcycle parts or equipment? Come here first. The friendliest Ninja 250R/300/400 forum on the internet! (especially Unregistered)

November 4th, 2012, 04:28 PM	#8
az3200 ninjette.org member Name: AZ Location: Orlando FL Join Date: Oct 2012 Motorcycle(s): 2002 Ninja 250 Posts: 213	so i'm a noob, but if you're cruising on the highway and swapped the front sprocket for the 15 tooth, and are at about 1000rpm less....about how much faster will the top speed of the bike be? 10mph or so?

November 4th, 2012, 08:32 PM	#10
ChaoSS ninjette.org sage Name: Tim Location: Goshen CA Join Date: Oct 2012 Motorcycle(s): 2012 red 250 ninja Posts: 740	You will change the theoretical top speed, the speed at which the bike would go if you could redline it in 6th, but that is not real world. My bike hasn't gone over about 94 indicated (on mine that's going to be just a hair over 90 actual speed) and that was no redline. Now, i'm a big guy, and I have saddle bags that add to the wind reaistance, and really hadn't perfected my tuck. That being said I wouldn't excpect much more out of a stock ninjette. I have a 15 tooth front on mine, for highway driving, keeps the rpms down a bit, and i'm thinking about a smaller rear, or a bigger tire. It isn't really like being in the next higher gear but when I first did it it did feel that,way

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Sprocket Change?	csmith12	2008 - 2012 Ninja 250R Tech Talk	17	April 9th, 2014 03:20 PM
Sprocket size change	mrudich	1986 - 2007 Ninja 250R Tech Talk	1	April 2nd, 2014 06:27 AM
15 41 sprocket change	gogiburn	1986 - 2007 Ninja 250R Tech Talk	4	September 22nd, 2012 02:05 PM
sprocket change	sacreyc	Help	3	July 12th, 2011 05:11 PM
Rear sprocket change	red	2008 - 2012 Ninja 250R Tech Talk	16	November 20th, 2010 07:30 AM