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Thanks for your responses guys.

So if my personal preference is to have more low end acceleration and less top end speed, it would be worth me getting a 13T Sprocket?
 

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as variously explained, acceleration will be spread thru the gears,
so yes, you will 'get more low end acceleration' but also similar
thru the other gears.. including 6th gear which will be a bit
more like 5th and less of an 'overdrive', thus you wont,
necessarily, 'lose top end speed' and in general use
could gain usable top end speed...

as rusty summarized, sprockets are cheap,
thus, its easy to suck it and see for yourself..
aufitt [i think] posted an excellent sprocket changing
how-to with detailed step by step and clear images...
 

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I think what people mean when they say "low end acceleration" is actualy "immediate torque to the rear wheel". Yes, lower gearing achieves that. In fact, since it's by ratio (%), the higher gear you're in, the more you'll perceive the change. Dropping to a 13T front will make 6th gear usable to modulate speed in normal highway traffic without downshifting to 5th.

Don't forget to order an electronic speedometer recalibrator when you do. I recommend the 12 o'clock Labs SpeedoDRD.
 

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I don't see why you'd need more torque in lower gears than the single already delivers. Compared to a Ninja 250R the CBR is pretty quick off the line already and it's never had a problem delivering torque when I needed it.
That's the main reason I traded to a CBR from a Ninja250R. While I liked the changes replacing the sprocket on my Ninja 250R produced (taller gears, less shifting) it certainly didn't cure all the Ninja 250R's problems. I still noticed sluggishness in 1st & 2nd and I lost a lot of top end in the process. It was worth the mod, but just barely.
Not like it was the only thing I tried. I put hundreds (if not thousands) of dollars of mods into my Ninjette and it still didn't run or pull as well as my stock CBR250R does right out of the crate.
Maybe I'm just inclined to like the characteristics of a single over a twin, but CBR runs almost exactly the way I want a bike to run straight from the factory and I don't see any need to mess with sucess.
 

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... I don't see why you'd need more torque in lower gears than the single already delivers...
Changing to a 13T front sprocket isn't really about increasing torque in 1st, and 2nd gear. In the first two gears the change with the 13T sprocket is virtually unnoticeable. In 3rd gear it is somewhat noticeable, but 4th through 6th gear is where it is a significant improvement in acceleration. My top speed now is 88 MPH, which the bike can easily accelerate to (although I rarely ride at that speed). With the 14T sprocket, top speed was 92 - 95 MPH and very dependent on ideal conditions. I am also at high altitude, which makes a big difference in performance... my bike has about 15 - 18% less horse power than it would have at sea level.

With the 13T front sprocket, the bike is so much more fun to ride.
 

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I think what people mean when they say "low end acceleration" is actualy "immediate torque to the rear wheel". Yes, lower gearing achieves that. In fact, since it's by ratio (%), the higher gear you're in, the more you'll perceive the change. Dropping to a 13T front will make 6th gear usable to modulate speed in normal highway traffic without downshifting to 5th.
Exactly.

Don't forget to order an electronic speedometer recalibrator when you do. I recommend the 12 o'clock Labs SpeedoDRD.
I installed the SpeedoDRD as well. It's easy to use, and can compensate for the factory speedo error, rear tire wear, or a rear tire size change, in addition to sprocket changes... well worth the $80.00 USD price.
 

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Thankyou guys, thus is great info.

I prefer a torquey bike than a bike with a top end that I can only use legally on a private road.

Will be doing this soon!:D

Sent from my Desire HD using Motorcycle.com Free App
 

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With the normal gear ratio, I am already in 6th gear going about 35. Goes to 13T in the front would essentially turn your 6th gear into 5th and you would make 1st gear useless. But if that's what you want, just get it. You'd only out $15-$20 if you don't like it.
 

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With the normal gear ratio, I am already in 6th gear going about 35. Goes to 13T in the front would essentially turn your 6th gear into 5th and you would make 1st gear useless. But if that's what you want, just get it. You'd only out $15-$20 if you don't like it.
Have you tried it?

Sent from my Desire HD using Motorcycle.com Free App
 

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... I am already in 6th gear going about 35...
And your motor is turning only about 3500 RPM at that road speed in 6th gear... so you don't think that's just a little bit below where this engine starts to make power? Wait, let me guess... you're going for 95+ MPG's... am I right?



... 13T in the front would essentially... make 1st gear useless.
I don't believe you... please continue, and enlighten us as to how you have come to this conclusion.
 

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stock = 14/38 or 2.71, one tooth less countershaft = 13/38 or 2.923..
difference only about 0.2 of final drive ratio,, enough to have some
effect but not enough to make 1st gear 'useless'..

these are incremental changes, according to personal preference/use..
you could go up 2 teeth rear sprocket for 2.85 [14/40] for a result
midway between stock and 13 tooth countershaft sprocket..

these minor changes would probably be handy for loads
pillions, steep hills and generally a little more access
to engine potential thru the gears, esp in a hurry..
 

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I just picked one up from FutureSport, they ordered it overnight.

Cost me $32.95 (Honda couldn't get any for a couple days).

10-KCZ-13
95-132113

461b78f2e39311e2a1ff22000a1fcee4_7.jpg

Edit: Installed. Oh my god. Amazing. Totally different bike!
 

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1st gear is basically for getting off the line, esp uphill, with a pillion
or other load [heavy rider, gear etc] thats is basic function..

taking off is more than just dropping the clutch, of course,
but just about anyone can get off the line on cbr250r
ahead of almost any general traffic.. you dont need
a gear change to achieve this function, just practice..
i left a large ducati behind off lights recently after filtering
to the front to find him there in the left lane, both entering
a single lane ahead.. didnt want to get in his way so let her
go.. maybe he wasnt trying, but he certainly roared past
as we eased off after second, staying to the right side
to let him past, which seemed fairly predictable..

a 13 tooth front sprocket would hardly make 1st useless..
the small incremental change would suit its basic functions..
 

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Question: Do we need to change any other setting on the bike if we install the 13T? Have been running it for sometime now but when I am riding slow in traffic, the chain seems to pull and struggle but once over 3k rpm, everything seems to be normal. I am just afraid, it doesn't break! :(
 

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Question: Do we need to change any other setting on the bike if we install the 13T? Have been running it for sometime now but when I am riding slow in traffic, the chain seems to pull and struggle but once over 3k rpm, everything seems to be normal. I am just afraid, it doesn't break! :(
Nothing to change aside from re-adjusting the drive chain free play. I'm running the free play at 1.250", where the chain is at its tightest points. I'm running a 13T front sprocket as well.
 

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Nothing to change aside from re-adjusting the drive chain free play. I'm running the free play at 1.250", where the chain is at its tightest points. I'm running a 13T front sprocket as well.
Does yours hit the swingarm when you lift it up? I put the 13T on mine, and adjusted it to ~30mm. Anything higher and it seems to hit the swingarm when I lift it up, feels a bit too loose. So aimed for 25-30mm.
 
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