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# Help With Math

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Situation = Upcoming ride with lots of fire roads.

Problem = Stock '06 crf250x needs more room up top.

Possibility = Sprockets, 50 tooth rear and a 13 tooth front

Question = Will a stock chain fit on the a fore mentioned set up with positive results?

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i had to chop 2 links when i put on my 49.

i have a 14/49 combo. see what happends with the axle blocks, maybe it'll work if you slide them all the way to the end...1 1/5 inch slack with the chain.

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I need to keep up with stock 450s on this ride without burning out my motor...should that set work?

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I've run a 14-48 set-up on the two track in upper Michigan and could cruise at 60 mph pretty easy and rev it out at 75 mph on a gps with my 250X.

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Thanks everyone. SO I guess that means that it would work for what I need to do. Any other suggestions would be great!

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14/49 would work well for higher speed fire roads. Always keep the 49 on the rear, and on the front, switch back and forth between a 14(for higher speed) and 13(for stock) gear ratios. The 13/49 combo would be very close to stock. And it's easier to swap the front sprocket. Check this chart for gear ratios . If you are trying to keep up with a 450x, stock is 13/51. Not sure what the 450r has on it.

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14/49 isn't that close to stock. 1 tooth front = 4 teeth rear. Stock is 14/53, which is 4 away from 14/49...so it's roughly the same as going up to a 15 on the front and leaving the rear a stock 53.

EDIT: I was apparently drunk when I wrote this. JTO's comment makes perfect sense. Please disregard.

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14/49 isn't that close to stock. 1 tooth front = 4 teeth rear. Stock is 14/53, which is 4 away from 14/49...so it's roughly the same as going up to a 15 on the front and leaving the rear a stock 53.

14/53 IS stock.

14/49 IS NOT close to stock.

13/49 IS close to stock.

Running a 15 on the front(with stock rear) would also work well for higher speeds, and would be similar to the 14/49...If it will fit

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<-- That's me bonking me

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Don't think you'd get a 15 on the front.

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Don't think you'd get a 15 on the front.

Word! Doesnt fit!!