anyhow, we switched to a 428 o-ring chain and a 49t rear sprocket, and what a difference. it'll still pull like a champ up the steep stuff, but it has legs now, too.

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will pattison

engineer, racer

ignition

www.ignitioninc.com

- Thread starter will pattison
- Start date

anyhow, we switched to a 428 o-ring chain and a 49t rear sprocket, and what a difference. it'll still pull like a champ up the steep stuff, but it has legs now, too.

------------------

will pattison

engineer, racer

ignition

www.ignitioninc.com

I have heard that it can make a difference which sprocket you change even though the final gearing may stay the same, does anyone know about this? (so would it be better to go down 4 in the rear, or up one in the front, or does it matter?)

Thanks,

Mike

Originally posted by will pattison:

**gearing it taller didn't seem like much of an option because of the 1 piece sprocket. turns out, the smaller ttr-125 comes stock with a 49. i bet that if you worked out the final gear ratios that they would be about the same, which also suggests to me that yamaha purposed geared it not to go very fast. makes sense for a beginner playbike.**

To expand on what Will said, Yamaha put a smaller rear sprocket on to compensate for the smaller rear wheel. TTR-125L = 16", TTR-125 = 14". Adding a larger diameter rear wheel effectively increases speed, so they geared the L model down.

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01 YZ250F

00 TTR-125L

00 TTR-90

00 PW-50

anyhow, i did the math, and the 3.77/1 ratio gives about a 5 mph advantage at 3600 countershaft rpm on the l-model. i don't know what the stock countershaft on the smaller ttr is, but at 3600 countershaft rpm, the speeds for the stock l-model and a 49/13 combo on the 14"-wheeled model are 41 mph and 39.77 mph, respectively.

wp.

my bad!

wp.

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