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Discussion Starter · #1 · (Edited)
Rear sprocket change of "negative two teeth", will that make a difference in performance. I have read it would increase my bandwith between the gears especially between first and second gears...

Second, I am looking to improve performance of my bike, OVERALL... dont care how much it cost for upgrades and Mods I just must want more torque and power. - Any suggestions would be appreciated

250 is great bike, its light weight and handles awsome around turns. I need the power and torque because I get onto highway alot...

Any suggestions would be appreciated
 

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not sure how a gear change would make your internet speed faster?

Honestly though, I can't comment on the rear sprocket change. Going two teeth less will give you a lower RPM at the same speeds, theoretically increasing your available top-speed. However, the CBR already lacks the power to top-out in terms of RPM and Gearing, so I don't see how it would benefit at all. It's just not the bike for power on the highway.
 

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As mOOse said, less teeth on the rear will give you less Gigabytes.

No amount of mods will ever pull that gearing.
Want to go faster- be a better rider.
 
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I think you may have been misinformed or just got your facts reversed? As stated a smaller rear sprocket will reduce the RPM's. Who knows MAYBE it would next a but better highway mileage. Maybe not however.

If you go 2 teeth bigger however, you would potentially get a bit better acceleration (this will do nothing to the ratio between 1st and 2nd however) at the expense of higher rpm on the highway. I don't know what the top speed 6th gear RPM is but I think it is not rev limited. In that case the top speed would not change much if at all.
You may lose a little MPG.

I is very common for owners of my current KLX250s to change the 14t front sprocket for a 13t for better dirt performance or a 15t for better road.
 

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I have been also trying to figure out where to go on gearing

I am thinking about doing a +2 rear gear.

as it sits now. I am 195lb in 6th gear at 75mph I am at either 7,500 or 8,000 rpm. Can't remember which it was.

Keeping this bike at 75 takes wide open throttle

I found this morning it loves to stay at 70MPH on the freeway.

Doing -1/+2 on my GSXR600 woke that bike up.

So I am thinking about doing a +2 rear. OR just waiting for my pipe.

The pipe woke my Wife's bike up.

I do not think the bike has enough power/tq to move it very well with a + front gear or - rear gear.
plus. All I can find are -1 front and +1/2 rear
 

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YES, There is already a 400 page thread on the topic.

Taller gearing will get your revs down and increase the MPG if ridden gently enough.

I suspect I'm already faster than you on the same bike. If you gear up, I'll be even faster than you.

I ride the highway daily. There is no lacking in the ability of this machine, only in the rider.
 

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If your bike is like mine you will quite often find it running over 9000 r.p.m. That is above the peak power output. Therefore changing the gearing as you suggest would give you a higher top speed under favourable conditions. ( i.e. downhill or with a tail wind). The downside is that you will have to run in 5th whenever you hit the opposite conditions ( otherwise you will slow right down as the bike drops back to 7000 r.p.m.)
As it is a lightweight and low power machine it is extra sensitive to these factors. The change you suggest will remove a lot of the top gear flexibility which personally I wouldn't trade.
 

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engine cant pull the taller gearing so you stay the same. doesnt help. going down in front and up back makes bike stay in redline all the time. fun to ride but really slow on top
 
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a rule i learned for my dirtbike is that for each tooth change on the front cs sprocket, that's almost the same as changing 3 teeth off the back sprocket. whenever i want to change my gearing, i'll change up the front sprocket instead of the rear. it's soooooo muchh easier to change out the front than to take the wheel off to change the back. a front sprocket is cheaper too, about 1/4 the price of a rear sprocket
 

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dont care how much it cost for upgrades and Mods I just must want more torque and power
If you have a money is no object attitude with modification, the cheapest, best thing you can do to get the power you want - is to buy a different bike. There isn't much you can do for cheap that will make the CBR into a better highway tool. The package as a whole satisfies many people who spend a lot of time on the highway (including myself) and I have no problems keeping up with the fast, aggressive, 85+MPH speed demons I contend with regularly, but if you really need more power there aren't any cheap ways to get more power out of this bike. Just buy a 650.
 

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heaps of info here and elsewhere as to changing front sprocket
which for various reasons is the generally preferred option..

best way of course is to suck it and see..
a new sprocket costs about a much as
6 cups of coffee...

as members repeatedly advise tho,
its subtle refinement, not like bolting
on a turbo-charger...
 

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Yes you are correct. i have a 37 T back/15 in front/ now the bike gets stuck at 8000Rpms/ compared to stock setting of 38T/14T. 9500Rpms. Also have speedo error also says 80miles/130km. but it feels i am doing 83/135km.
 

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15t/37

Has anyone did -2 on rear or +1 on front sprocket?
I have just done it recently, the bike is now a different. the ODO is gone off i do not know if i am covering the correct distance. Max the engine the MPG drops significantly and very easily in this setting. I suggest who ever it is out here and On the web, this above setting is a bit less likeable on express ways, but in curves you can really adjust your throttle as fine as possible, no more bucking from off to on throttle, it is a linear throttle you can make other stock sprocket CBR 250 look like they are struggling on turns. you can add quite a lot more speed in turns on mountain runs vs stock setting.
 

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Yes you are correct. i have a 37 T back/15 in front/ now the bike gets stuck at 8000Rpms/ compared to stock setting of 38T/14T. 9500Rpms. Also have speedo error also says 80miles/130km. but it feels i am doing 83/135km.
I have just done it recently, the bike is now a different. the ODO is gone off i do not know if i am covering the correct distance. Max the engine the MPG drops significantly and very easily in this setting. I suggest who ever it is out here and On the web, this above setting is a bit less likeable on express ways, but in curves you can really adjust your throttle as fine as possible, no more bucking from off to on throttle, it is a linear throttle you can make other stock sprocket CBR 250 look like they are struggling on turns. you can add quite a lot more speed in turns on mountain runs vs stock setting.
Sounds like you have your thinking backwards where final drive gearing is concerned. The 15/37 gearing that you are running is not going to be ideal for quicker acceleration out of corners, and certainly not quicker than the stock 14/38 gearing. Many of us have replaced the front 14T sprocket with a 13T, which results in a lower final drive ratio, to improve acceleration over the stock set-up. The primary reason that someone would want to change to taller 15/37 gearing on this bike is for improved MPG's at higher speeds as you would have on freeways. This taller final drive ratio effectively reduces the engine RPM's at a given road speed, to result in improved fuel economy. However this improved MPG comes at the expense of slower acceleration.
 

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if money is no problem than why not use it for a high-comp kit? A member did this and his bike now is 305cc, as I recall the bike can produce 30+hp with that kit.
 
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