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ok.. so i'm not a mechanic or anything, but i think i can safely assume that the bigger the gap between gear ratios you have; the bigger range of speed you can have because of differences in torque. Why aren't the bikes designed with larger gaps between the gears? The way i'm seeing it.. if this was done, bikes would be able to run at lower rpm's at higher speeds. when i say this, i'm particularly thinking about my ninja 250 and how i'm running at 7-8k RPM on the highway.. which i think is ridiculous.
 

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ok.. so i'm not a mechanic or anything, but i think i can safely assume that the bigger the gap between gear ratios you have; the bigger range of speed you can have because of differences in torque. Why aren't the bikes designed with larger gaps between the gears? The way i'm seeing it.. if this was done, bikes would be able to run at lower rpm's at higher speeds. when i say this, i'm particularly thinking about my ninja 250 and how i'm running at 7-8k RPM on the highway.. which i think is ridiculous.
Smaller displacement engines make speed, HP and torque at higher rpms. If there were not enough close ratio gears, the bikes would have 3-4 speeds and it would take too long for top speeds to be reached. So instead of 0-60 in 8-9 seconds, it would be 0-60 in about a minute or two depending on the incredible mods you put on your 2fiddy.(ok maybe a slight exaggeration)

Redline on my Ninja is 13000. If I run 75 mph, I'm running about 7.5k rpm in 6th gear, which is half of the max engine speed. which is ok by me.
 

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racerboy629
Apprentice Ninja

Join Date: Jun 2008
Posts: 21



16 Tooth front sprocket
Hey everyone, just wanted to post a little more gearing information for those that might think about changing their sprockets to make a difference in their ride.

I primarily use my 250 as a mode of transportation to and from work. And that's 40 miles one way, all of which are on the highway. So for me, the stock gearing absolutely sucked. So I went the cheaper route first, and swapped the front 14 tooth for a 15 tooth. That made a nice difference. Especially since the internal gear ratios for first gear are so low, it would let this bike pull a small truck.

But always being on the highway screaming at 9000 RPM's... it was killing my fuel economy. So the 15 tooth was nice. I would reccomend it to anyone. I went from 55MPG up to 60MPG with this $13 mod. Well worth the money.

Then I wanted a little more, so I started on the rear. I went from a 45 tooth to a 43. That was a little better for me. Would let me cruise @ 65-70 mph at just over 7500 rpm, and fuel economy went from 60MPG to now averaging about 64-65mpg pretty consistently.

Then my parts guy, Joey, called me and told me that he could get me a 16 tooth front sprocket if I wanted it. I said sure, why not?

About 10 days later, it showed up in the mail.

So I decided to put it on. Which is where the challenges came up. Because that sprocket is SO BIG, that the countershaft cover wouldn't go back on once I had it all bolted on. So I had to take it off, and grind part of the cover away, in order to let the sprocket turn w/o grinding on the cover. (what I mean by grind some of it away, is where the chain came into contact with it when it was bolted back on. Not CUT part of it off per se.) So I just ground down a 2 inch line around the inside of it. You can't see it when it's bolted back on.
Not like it was difficult or anything, just took some time with a dremel and a cutting tool.

(MAKE SURE YOU WEAR SAFETY GLASSES, BECAUSE YOU WILL HAVE ALUMINUM FLAKES SHOOTING EVERYWHERE!!!!!)

It took me several attempts at doing some grinding, then putting it back on to check clearances. But after the 4th or 5th time, I finally got it right, and the wheel would spin w/o the chain hitting anything.

So then it was time to ride.
Now, remember, I'm running +2 on the front, and -2 on the rear: that's a HUGE change.

First gear wasn't that different, again, because it's geared so low internally. But when you click from second to third... and so on.... HOLY SH!T what a difference. It's like my ZX6. You can pull each gear for a really long time.

So I left it that way for a few days. On any type of hill.... I fould myself having to click down a gear to keep my speed up. Then another gear..... and another gear.

It was just TOO tall for the little motor to pull w/ any type of authority.

So I pulled the back wheel off, and put the stock rear on, which left me with a 16T front, and a 45T rear.

And after having that on for the better part of 2 weeks, I am happy to post, that I am running a consistent 65MPG on the highway, and rolling @ 70mpg at between 6500 and 7000 RPM.

For me, this is the perfect gearing. It will pull myself with my girl on the back from a light w/o a hitch, and cruise up most gradual hills w/ not so much as a grunt.

Now mind you, I've also done the $36 exhaust mod, and shimmed the needles 0.010, removed the snorkle, and re-sync'd the carbs. So it ran pretty good before the gearing was done. But now....
I'd reccomend the 15T to anyone. And for anyone that does any touring, or long distance rides... you'd be happy with the 16T if you wanted.

Since nobody else seems to be able to get any sprockets for the 250, my parts guy's name is Joey, like I mentioned before. He can be reached @ 800-596-6199. Tell him Todd from Florida told you to call, (he's in Ohio) and he'll give you more information than you'll know what to do with... besides being able to get you anyting that you want. Including the VENTURA rear seat bags that nobody in Florida can seem to get either.

Anyhow... I hope everyone finds some use out of my gearing experimentation. And I'll try and answer any questions that come up.








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i'm changing my 400 sprockets the front up 2 teeth and back down 3 and my rpm will still be higher than the 650 at same speed.
 

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i'm changing my 400 sprockets the front up 2 teeth and back down 3 and my rpm will still be higher than the 650 at same speed.
I believe the stock front sprocket is 15 tooth. A 16 tooth would be pushing the limit. You may not have the clearance in the sprocket cover for a 17 tooth. I know a 16 tooth sprocket rubb the sprocket cover on the 250.

A 15/42 will gain you about 7 mph @ 6.5k and 10 mph @ 9.5k rpm.
 

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jt sprockets makes an 18 tooth for front sprocket on 650.already measured and 17 will be max for my 400. the 43 tooth rear will also help to not have to remove chain links.oh and the ninja 300 comes 14/42 thats 3 tooth drop on rear from the 250 14/45
 

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650 stock is 15/46. I'm gunna try 16/46.....
That will get my speedo right.....
It should make it better for me in shifting so quick out of first gear.
Other forums say it will spred out the gears better for cruising....
I'm also gunna try these sprockets.
Titanium II Sprocket Lifetime Guaranteed Titanium 2
Hoping to get the front one a tooth bigger too.
Chain: TITANIUM II SERIES-
12,000 lb..............$119.99
http://sidewindersprockets.com/titanium_chain.html









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for the 250 i would only going up 1 tooth in front otherwise city driving will give needless wear on clutch.i hardly ever use light to light traffic so most of my driving at highway speeds thats why 2 tooth on front 3 less on back will be perfect for me.
 

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ok my manual says my idle is supposed to be 1250-1350 rpm and i'm supposed to shift from 1st to 2nd gear at 2000 rpm,and from 2nd to 3rd gear at 2350 rpm etc...then what is my peak torque 7500 rpm and peak hp 9500 rpm good for?
 

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ok my manual says my idle is supposed to be 1250-1350 rpm and i'm supposed to shift from 1st to 2nd gear at 2000 rpm,and from 2nd to 3rd gear at 2350 rpm etc...then what is my peak torque 7500 rpm and peak hp 9500 rpm good for?
That's for u to say......:facepalm::facepalm:
fck the manual n ride......:facepalm::facepalm:
I have a 650...not a r....
Idle at 1350-14.....wont idle smooth under that....:eek::eek:
I always shift at 4 grand min ---> 6....
My redline is only 11, but never go near it.
Well unless it's the few times i'm cranking....
Usually never go above 8......:angel:
My power level seems to start at 4 n goes strong to what i think is 10... maybe 9.5? Hard to tell....:whistling:
Usually where my idle is a bit high to get a smooth idle at long lights
i will kill the bike n leave it in first gear......:dance:
I get tired of holding the clutch a long time...
It doesn't like the shift from neutral to first without a lurch.
So i'll start in first with clutch pulled.:thumb:
I'll warm it up in neutral, but kill it n start it again in gear....
avoid that lurch when i can.:thumb:
I've had the shop check it out...n..the mechanic says my bike just don't like to idle below 1350.....:eek::eek:
Not sure how other 2012 Ninja 650's are???????








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before doing any gear or sprocket change evaluate your % of slow/city or fast/highway riding also acceleration (does your bike have enough torque/hp to compensate ?) there are pros and cons to everything thats why most bikes come from factory with the most versatile gearing.i'm old but hate crusers and i dont need 60+hp.my reason for getting a bike is probably different from the next guy.my advise is modify your bike so it suits you best and if you dont like the mod then change it again thats the fun of motorcycling just get out and ride.
 

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before doing any gear or sprocket change evaluate your % of slow/city or fast/highway riding also acceleration (does your bike have enough torque/hp to compensate ?) there are pros and cons to everything thats why most bikes come from factory with the most versatile gearing.i'm old but hate crusers and i dont need 60+hp.my reason for getting a bike is probably different from the next guy.my advise is modify your bike so it suits you best and if you dont like the mod then change it again thats the fun of motorcycling just get out and ride.
:thumb::thumb::thumb::thumb:








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