December 30th, 2008, 05:29 PM | #1 |
The Grand Royal
Name: Cochese
Location: Unmarked Rustbox
Join Date: Dec 2008 Motorcycle(s): 2009 Ninja 250R Posts: 258
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Lets talk sprockets!
Okay folks...
I will soon have a full exhaust, jet kit, filter, airbox and kleen sys delete all installed and dynoed. I need to bring the RPM's down. I took it on the interstate yesterday at 80 mph and it was too high for me. I want to bring down the revs and not kill my power. With the listed mods, what tooth count do I need for front and rear? Do I need to do BOTH front and rear or just front? Or just rear?? Which brand is the best for weight and strength vs price? I want black ones since black is fastest and undetected by radar. Thanks! |
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December 30th, 2008, 06:22 PM | #2 |
ninjette.org certified postwhore
Name: Sam
Location: Northern Virginia
Join Date: Nov 2008 Motorcycle(s): Ninja 250R 2009 and ZX-12R 2000 Posts: A lot.
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Of course, you were on "Police" business, i.e. road testing your new "pursuit" vehicle! Are you going to put white "swooshes" on it, in order to make it an official "black and white"?
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December 30th, 2008, 06:28 PM | #3 |
ninjette.org certified postwhore
Name: Sam
Location: Northern Virginia
Join Date: Nov 2008 Motorcycle(s): Ninja 250R 2009 and ZX-12R 2000 Posts: A lot.
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Also, check this DIY. It may answer some of your questions!
http://www.ninjette.org/forums/showthread.php?t=10273 |
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December 30th, 2008, 07:05 PM | #4 |
That's me!
Name: TJ
Location: Ames, IA
Join Date: Nov 2008 Motorcycle(s): 2008 Ninja 250r (Tis blue), 2008 CBR600RR Posts: 454
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I did this speal one time on another forum:
OK this got a little long... First you have to figure your 'total gearing'. Just divide the front sprocket by the rear sprocket. ie. .................................................. . And just for fun 14/45 --- 15/41 --- 15/42 --- 15/43 --- 14/49 .311 ---- .3659 --- .357 ----- .3488 --- .2857 Then start with something 'known' like the STOCK 14/45 gearing (which overall gearing is .311) 1st - 36.1 2nd - 52.57 3rd - 66.75 4th - 81.1 5th - 94.1 6th - 105.4 Then just find the difference between two sets of gearing and multiply each gear: and then multiply the known gearing (ie. the 14/45 max RPM speeds) by that number ------- 14/45 ---- 15/41 ---- 15/42 ---- 15/43 ---- 14/49 --------1.0 ------ 1.176 ---- 1.147 ----- 1.121 ---- .9186 1st ---- 36.1 ----- 42.45 ---- 41.4 ----- 40.5 ------ 33.2 2nd --- 52.57 ----- 61.8 ----- 60.3 ----- 58.9 ----- 48.3 3rd ---- 66.75 ---- 78.5 ----- 76.5 ------ 74.8 ----- 61.3 4th ---- 81.1 ----- 95.4 ------ 93 ------ 90.9 ----- 74.5 5th ---- 94.1 ----- 110.6 ---- 107.9 ---- 105.5 ----- 86.4 6th ---- 105.4 ---- 123.9 ---- 120.9 ---- 118.1 ----- 96.8 Then to figure what RPM you'd be spinning in say 6th gear, just figure out what that speed is compared to the top speed, so... ---------14/45 ---- 15/41 ---- 15/42 ---- 15/43 ---- 14/49 6th ----- 105.4 ---- 123.9 ---- 120.9 ---- 118.1 ---- 96.8 65 mph - 61.6% --- 52.4% ---- 53.7% --- 55% ------ 67% Then multiply THAT percentage by the max RPM (13,000) to figure out the RPM you'd be spinning at that speed --------- 14/45 ------ 15/41 ----- 15/42 ------ 15/43 ------ 14/49 65 mph -- 61.6% ----- 52.4% ----- 53.7% ----- 55% ------- 67% --------- 8000 RPM -- 6810 RPM -- 6981 RPM -- 7150 RPM -- 8710 RPM |
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December 30th, 2008, 07:20 PM | #5 |
Join Date: Nov 2008 Posts: Too much.
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Cliff notes, Vex!!! what does he need??
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December 30th, 2008, 07:51 PM | #6 | ||
The Grand Royal
Name: Cochese
Location: Unmarked Rustbox
Join Date: Dec 2008 Motorcycle(s): 2009 Ninja 250R Posts: 258
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Quote:
Quote:
Pig! |
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December 30th, 2008, 07:51 PM | #7 |
The Grand Royal
Name: Cochese
Location: Unmarked Rustbox
Join Date: Dec 2008 Motorcycle(s): 2009 Ninja 250R Posts: 258
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December 30th, 2008, 07:52 PM | #8 | |
The Grand Royal
Name: Cochese
Location: Unmarked Rustbox
Join Date: Dec 2008 Motorcycle(s): 2009 Ninja 250R Posts: 258
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Quote:
Now I can go find an engineer to figger out this here mathematics for me! |
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December 30th, 2008, 07:57 PM | #9 |
The Grand Royal
Name: Cochese
Location: Unmarked Rustbox
Join Date: Dec 2008 Motorcycle(s): 2009 Ninja 250R Posts: 258
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So the lowest RPM in 6th gear without sacrificing power or acceleration below an acceptable level would be a 15/41 at 52.4% / 6810 RPM / 65 mph?
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December 30th, 2008, 08:07 PM | #10 |
Join Date: Nov 2008 Posts: Too much.
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I believe most that re gear for the highway recommend the 15/41 combo.
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December 31st, 2008, 08:08 AM | #11 |
The Grand Royal
Name: Cochese
Location: Unmarked Rustbox
Join Date: Dec 2008 Motorcycle(s): 2009 Ninja 250R Posts: 258
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Thanks Kelly!
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December 31st, 2008, 10:38 AM | #12 |
ninjette.org certified postwhore
Name: Kim
Location: mundo de ensueño
Join Date: Nov 2008 Motorcycle(s): '08 250 Posts: A lot.
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This might also be helpful:
http://www.gearingcommander.com/ |
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December 31st, 2008, 10:59 AM | #13 | |
ninjette.org certified postwhore
Name: Sam
Location: Northern Virginia
Join Date: Nov 2008 Motorcycle(s): Ninja 250R 2009 and ZX-12R 2000 Posts: A lot.
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Quote:
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December 31st, 2008, 09:00 PM | #14 | |
ninjette.org sage
Name: David
Location: Wellington, New Zealand
Join Date: Dec 2008 Motorcycle(s): 08 Ninja 250R in Green! (Sold) Now 2011 Triumph Daytona 675 SE Posts: 564
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Quote:
I too am considering changing my sprockets as ~80% of my riding is at 100kph (62mph) and would like to have the bike rev lower at this speed. Would running a 15/41 reduce accelleration by much? (changing the sprockets will be done after I have finished with my engine mods.) |
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December 31st, 2008, 09:34 PM | #15 |
ninjette.org dude
Name: 1 guess :-)
Location: SF Bay Area
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Yes. Once you're up and moving > 20 mph, the difference won't be as noticeable. But starting from a dead stop with 15/41 instead of 14/45 will be very noticeable.
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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) |
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December 31st, 2008, 09:37 PM | #16 |
Join Date: Nov 2008 Posts: Too much.
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Which is why this gearing mod should be done in conjunction with the jetting/power mods. It will sure help the anemic low end of a stock bike.
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December 31st, 2008, 09:41 PM | #17 |
ninjette.org sage
Name: David
Location: Wellington, New Zealand
Join Date: Dec 2008 Motorcycle(s): 08 Ninja 250R in Green! (Sold) Now 2011 Triumph Daytona 675 SE Posts: 564
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OK, I thought as much, question that will be hard to answer coming. What about the accelleration of the 15/41 combination with AP full exhaust, stock jets shimmed (possiblly dynojet stage 2 ket) and snorkel removed, Kleen air system removed, compared to a fully stock bike?
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December 31st, 2008, 09:46 PM | #18 |
ninjette.org dude
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Simple question, yet impossible to answer simply. Much of what you'll get online (even from the very best forums like this one ) depends on "it feels fast", "it feels smoother", "it sounds better", "the powerband is more noticeable". All of these things may or may not be true, but it's really impossible to know. If it is of concern to you, take some objective performance measurements now, as accurately as you can, and then take the same measurements after the mods to see if there is a noticeable difference to you. One way is going to a drag night at a local drag strip, another way (perhaps not as accurate, but certainly easier to arrange) is simply timing acceleration runs yourself, or with a friend to man the timer.
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December 31st, 2008, 09:54 PM | #19 |
ninjette.org certified postwhore
Name: Kim
Location: mundo de ensueño
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If you or a friend have an i-phone you might be able to use the accelerometer on it....
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December 31st, 2008, 09:58 PM | #20 |
ninjette.org dude
Name: 1 guess :-)
Location: SF Bay Area
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As I read back my post (#18) I wasn't happy with it. You're looking for a simple answer, and you're entitled to one, so I'm going to give it another shot.
Increasing the gearing from 14/45 to 15/41 is a 17% increase. That is significantly taller. A stock new-gen ninjette motor dynos somewhere around 26 hp at peak. Give or take 1 hp. The strongest claim I've ever seen for a new-gen motor with every mod you've described will dyno somewhere around 31 hp at peak. A 19% increase in power. Put those two pieces together, and a back-of-the-envelope guesstimate says you'll end up with roughly the same acceleration as a stock bike. But with about 17% less revs at highway speed. Perhaps in the 8000 range instead of the 9800 range at a good highway pace. If it were me, I'd spend the money & time on trackdays and rider skill improvement rather than bike improvement, but last I checked I'm the only me.
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December 31st, 2008, 10:04 PM | #21 |
Join Date: Nov 2008 Posts: Too much.
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Except the people doing this gearing mod are looking for a smoother running bike at prolonged highway speeds thru lowering the rpm at set speeds. No amount of track time will affect the bike's inherent mechanical abilities.
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December 31st, 2008, 10:08 PM | #22 |
ninjette.org dude
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True. I just don't hear, feel, or sense much difference in a ninjette engine doing 8000 rpm vs. one doing 10000 rpm. Both of them feel like an engine that is spinning surprisingly quickly, yet given normal maintenance can be counted on to do so reliably for years.
People like to tweak, and there's no reason to discourage that. I just wish that along with the tweaking there were more objective measurements available (dyno tuning, acceleration testing, calibrated top-speed measurements) after the tweaking. It would give people a better idea of what to expect with the changes they were contemplating, like these sprocket mods or anything else.
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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) |
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December 31st, 2008, 10:19 PM | #23 | ||||
ninjette.org sage
Name: David
Location: Wellington, New Zealand
Join Date: Dec 2008 Motorcycle(s): 08 Ninja 250R in Green! (Sold) Now 2011 Triumph Daytona 675 SE Posts: 564
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Quote:
Quote:
Quote:
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Kelly has it exactly right regarding the tracktime statement, I would like my bike to run as nice as I can get it before I start on track days. |
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January 1st, 2009, 08:45 AM | #24 |
ninjette.org certified postwhore
Name: Alex
Location: Belfast, ME
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It sounds like this whole gearing discussion is predicated on how your bike will be used. In my humble opinion, if the bike is used primarily on secondary roads and only periodically on turnpikes, the stock gearing is OK but not ideal. Riding on the New York State Thruway from Troy to Syracuse, I was keenly aware of how underpowered my bike was. Realistically you can only do so much to a 250. Were I making regular trips of this kind, I seriously doubt that the Ninjette would have been the bike I chose. The 650R would have been a much better choice. Since Route 5 paralells the Thruway, I can always use route 5 with the Ninjette and be in my element. 90% of ny riding is on secondary roads with a speed limit of 55 to 65mph. That`s perfectly fine for the 250. The scenery is also better and there is less traffic to contend with. A great part of the enjoyment one gets from riding a bike is being able to appreciate the sights and sounds of one`s surroundings.
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January 1st, 2009, 03:51 PM | #25 |
Track Junkie
Name: Jon
Location: Dallas
Join Date: Dec 2008 Motorcycle(s): '08 Ninja 250r Track Bike, DR350 commuter, KDX220 woods bike Posts: 602
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maybe this was mentioned already, not sure....
don't forget that you need to buy a new chain too if you have very many miles on your current one. sprockets and chains need to be changed as a set or they'll wear each other out faster.
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Las Escobas -- Track Bikes Save Lives JonBroom.com |
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January 1st, 2009, 06:40 PM | #26 | |
The Grand Royal
Name: Cochese
Location: Unmarked Rustbox
Join Date: Dec 2008 Motorcycle(s): 2009 Ninja 250R Posts: 258
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Quote:
When the sprockets go one, it'll be in conjunction with a FP 3.0 kit, K&N, airbox and Kleen delete and Area P/HR1 bastard full exhaust. Just need to pick the best sprockets from the available selection. My only requirements are the highway setup 15/41 with light/strong and hopefully black sprockets. Suggestions on brand? |
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