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Discussion Starter #1
has anyone been able to figure out where to find aftermarket rear sprockets? Im sure they share the same bolt pattern with other honda models....anyone know which ones?
 

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Another of your threads I will be watching closely. I think having better acceleration around town/backroads would be more valued than top end.
 

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Discussion Starter #7
Im looking for rear sprockets. let me know if you have figured out what other bike fits the rear. thanks.
 

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Once this bike gets delegated to the "fun bike" rather than "learner bike"and "daily driver bike", I'll switch to a larger rear to improve acceleration in the speeds in which the bike spends the most time traveling.
 

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Discussion Starter #10
Yeah, i dont want a smaller sprocket. this is a race bike from day one. it only has dyno miles so far, but i know the stock gearing is going to be way too tall.
 

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Race

Yeah, i dont want a smaller sprocket. this is a race bike from day one. it only has dyno miles so far, but i know the stock gearing is going to be way too tall.
Because the power band of the cam has it's peak at a lowish, 8,800 rpm, you will be losing some of the meager top speed the CBR250R comes with, the shorter you go with the gearing. The Ninjas will already blow right by you now on any track with a straight away. With an exhaust for an additional 1.5 hp, and longer gearing so that top speed occurs at 8,800, we should make a big gain in top speed.
 

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Ok, I talked to them today -- rears are coming soon, they said under 3 weeks. They will be available in 38, 39 and 40 tooth rears -- other sizes and the fronts to be released later.
 

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Discussion Starter #13
youre not going to want taller gearing. im pretty sure the bike isnt going to pull to redline in 6th gear. and all this talk of not being able to keep up with ninjas is bullshit. our race prepped ninja that we've been winning endurance races on all year with a pipe and jet kit, only made 28 hp and 14 ft lbs.

our brand new CBR on the very same dyno, back to back made 24 hp and 15 ft lbs, bone stock. with exhaust, fuel, no airbox and MR12 fuel, it WILL make more than 28 hp. It was also 21 lbs lighter in full showroom trim than our race ninja.

the bike will need at least a 40t rear.
 

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Youtube vid of CBR showing some Ninjas the tail light

Here's a great youtube track vid of a CBR250R showing some Ninjas the tail light.

It could just be that he's a better rider, but it's a fun watch just the same.


'njoy,
awk
 

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Dyno

youre not going to want taller gearing. im pretty sure the bike isnt going to pull to redline in 6th gear. and all this talk of not being able to keep up with ninjas is bullshit. our race prepped ninja that we've been winning endurance races on all year with a pipe and jet kit, only made 28 hp and 14 ft lbs.

our brand new CBR on the very same dyno, back to back made 24 hp and 15 ft lbs, bone stock. with exhaust, fuel, no airbox and MR12 fuel, it WILL make more than 28 hp. It was also 21 lbs lighter in full showroom trim than our race ninja.

the bike will need at least a 40t rear.
Well, I see you have your heart set on winning with the Honda and I would be very happy to read about your project. Please keep us posted.
Most of the dynos of the CBR250R I've seen show hp less than 22hp stock. With the best slip on + fuel trim raising that to 24hp and still down at 8,800 rpm. The fuel economy tuned cams peak at around 8,500 rpm. A street tuned Ninja will be 29hp at 11,300. Does top speed occur at redline or at the power peak? The Honda doesn't have the revs that the Ninja does so it will need longer gears if the track has any top speed section to get the best top speed down into the power band. To be a competetive racer, the CBR250R will need a higher compression piston, racing cams, and an ignition over ride for higher revs to go with the exhaust and fuel trim.
 

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Yeah, i dont want a smaller sprocket. this is a race bike from day one. it only has dyno miles so far, but i know the stock gearing is going to be way too tall.
I'm a relatively new rider, can you tell me the indications of too-tall gearing? thanks
 

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Discussion Starter #18
I'm a relatively new rider, can you tell me the indications of too-tall gearing? thanks

well as far as racing goes. too tall means poor acceleration out of corners. you shoul dbe able to reach redline, in top gear on the track's longest straight.

the bike is currently geared to theoretically go 137 mph...obviously, thats never going to happen.
 

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105 mph

well as far as racing goes. too tall means poor acceleration out of corners. you shoul dbe able to reach redline, in top gear on the track's longest straight.
the bike is currently geared to theoretically go 137 mph...obviously, thats never going to happen.
The CBR250R is currently geared for 104.5 mph actual at 10,500 rpm according to my experience with the actual tire circumference of 77.00 inches at gearing commander. I am currently topping the stock bike at 93 mph actual and 9,400 rpm.
 
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