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Right now i have a 1992 ZX7R K model with the flatside carbs. I have a Full muzzy exhaust and im soon gonna get a Jet kit for it. Well Ive read alot about sprockets ehancing performance but im not sure where to go. Any recomindations on what sprocet sizes i should get on the front and back and what the pros and cons would be ?
 

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"Enhancing performance" means different things to different people. I'll tell you my opinion, and others may feel free to disagree.

Motorcycle sprockets work just like bicycle sprockets. If you switch to a smaller sprocket on the front, or a bigger sprocket on the back, then you will have to turn the engine more to get the same speed. In other words, you'll have less speed, but more power, which means you'll reach top speed quicker.

Think about it this way. If you put your bicycle into it's lowest gear, you can take off really fast, but before long, you're pedaling like crazy and not getting anywhere. In contrast, if you put the bicycle into it's highest gear, you have to stand up on it to get it to take off. But once it's going, you can really fly. Sprocket changes on a motorcycle work the same way. Changing your front or rear sprocket gives you either more "take off acceleration" in first gear, or more "top speed," but you have to choose which one you want.

In my opinion, sprocket changes really only affect first gear and your highest gear. If you want a quicker start off the line, then a smaller sprocket in the front (or a bigger one in the back) will help you out in first gear. But you'll have to shift sooner, and more frequently, and you'll lose some top end speed. Plus, your highway RPM's will be higher.

I have a Ninja 250R, and this thing revs way too much for my conservative tastes. So I am planning to install a larger sprocket on the front and a smaller one on the rear. That will give me less first gear acceleration, but it will lower my highway RPM's. It will also spread out the gears so I don't have to shift as often. That's what I call "enhancing performance." For some people a 250 just isn't enough power, so they want to change the sprockets the other way. But for me, the 250 has more power than I need, so I'm willing to lose a little in order to lower my highway RPM's.

By the way, it is sort of a misnomer to say that a larger front sprocket or a smaller rear sprocket will increase your maximum speed. That depends a lot on your bike. My 250 has a top speed of about 114MPH. I would redline it at that speed, and just can't go any faster. If I change my sprockets, then my redline would occur at a higher speed, like maybe 120 or 125. But I can't get there because I just don't have the power. So for my bike, changing sprockets won't increase my top speed. For me that doesn't really matter, since the highest speed limit in Minnesota is 70MPH.

One other thing to consider when changing sprockets, is that it's generally a bad idea for chain life to change to a smaller front sprocket. It's not really the worst thing in the world, but it will make your chain wear faster because of the tighter turning radius. A better solution is to go to a larger rear sprocket, but that will cost more, and will be more labor to install.
Curt
 

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generally dropping one tooth in the front is equivalent to about 3 up in the rear, depending on the bike. most people that want a change go down 1 in the front and up two in the rear(which is like 5 up in the rear without getting a new chain). smaller sprockets up front do wear more but if you keep your chain properly maintained so it doesnt have hard spots it should be fine. What exactly are you looking for out of your bike? quicker accel? wheelies? as curt said it merely shifts your power band. you put more power down lower because your bike is revving harder to get there. so say before your cruising at 25 doing 5 grand in 3rd now your rpms would be higher so when you open the throttle up your closer to peak power, make sense?
 
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