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Semi-Wide Ratio 2010+

4 posts in this topic

Well, after much contemplation, I decided I needed a wider 4/5 gear ratio on my 2010 YZ 450. I compared a few notes and part #s, and it looked like the gearsets from a 2007 WR 450 should drop right in, almost.....All the gears slipped right on except for 5th gear whl, apparently Yamaha used a coarser spline on that gear on the '10 models. Time for more thinkin' and scratchin'..Looked like if I used a 2007 WR output shaft, it should still be a drop in modification. (this output shaft is also the same one used on the pre '10 YZ models as well) I ordered one in and yup, it all bolted together and bench tested just fine....

Below are the parts I swapped in:

5TJ-17241-20-00 (4th whl)

5TJ-17141-20-00 (4th pinion)

5TJ-17251-20-00 (5th whl)

5TJ-17151-20-00 (5th pinion)

2S2-17402-00-00 (output shaft)

90209-21332-00 (washer)

The above parts retailed for 275$ (+gaskets) but I shopped the internet and picked them up for 190$ or so. I'm recovering from a bit of surgery, and won't actually get out for a couple weeks yet, but it looks like I have a 4th gear that is 11% taller than stock, and a 5th gear that is 17% taller than stock....While keeping the stock close ratio 1-2-3 for squirting out of the corners...!!:thumbsup:

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Just got back from a quick ride this morning, and I like the extra gear(s). I rode a bit of mixed single track, sand wash and Jeep trails. I'm running a 13-52 combination, as there are a lot of narrow steep single track trails on this loop. I don't find I go any faster, but the motor gets to loaf a bit on the faster Jeep trails and sand washes. As I've been riding this thing for a year or so, I notice the difference between 3-4 and 4-5 shifts, if someone was to use this gearbox from day one, they would never miss the closer stock gaps between the gears.. There is so much power from the motor, it never once was an issue with seeming to big of a gap between gears. Other than a Super Cross application, this is the gear spread that should have been OEM from Yamaha for most of us mortals...!!:busted:

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