# xr100 sprocket size

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I have a 2003 xr100 with fmf power core 4 system and uni filter but i want to make it go faster now that I have the power to push it so stock gears are 14/50 so should I go 15/50 or 16/50 do you think 16t in front would be too much

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you would lose a lot of power if you went 16/50. Mabey it would work on a super motard setup, but im assuming thats not your case... I tried 15/46 (which is basically 16/50) on my xr100 with a 120bbk and it didn't have the power for it. 15/50 sounds like it may do good though...

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One up of the front equals 3 on the rear... For example

14/50 15/53 16/56 are so close in ratio you hardly notice a difference... Simple math

Divide 50 by 14 to get your ratio and so on.... I'm a big guy and I have elected to go witha large front sprocket... 16 and 17 and change the rear accordingly...

I figure the larger the sprocket on the front, the less work the motor has to do to turn it and it does not bind the chain as much thus, creating less wear...

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This topic has been covered before, so I guess I'll throw a wrench into what's generally believed. There are two things going on math and physics. Everyone knows the math side, the simple ratio effect of the the the tooth size, but equally important is the increase in radius of the sprocket. With an increase of radius with either sprocket you have an increase of leverage, so a 16t/53 doesn't ride like 15/50, even though mathematically it should. As the front sprocket increases the countershaft has more leverage and as the rear increases in radius it spins the wheel easier, etc. Anyway, you have to test different sprocket sizes and get a set up that works for you with the way you ride. On my kx/xr120 I rode a 15/47 for years, but on my cr/xr120 I rode a 15/53. I still haven't figured that one out. So it all depends on a lot of factors. I tried a 16t setup and didn't like it, but I'm only a buck fifty, whereas the guy in the above post said he liked a 16t's, but he's a big guy. So it all depends.

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I went one up on my front sprocket and it did wonders . I can still lug up hills easily, ride wheelies,and it seems to have quite a bit more speed:thumbsup: I did this to my ttr 125 btw.