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What size rear sprocket on a WR250R


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I just bought me a 08 WR 250R today and I got on it to ride and the thing had no power. So I looked at the rear sprocket and it said 43. To me, that sounds to small. What size is stock on these bikes? Ill be doing a mix of street and woods riding. Should I go bigger then stock size. Thanks in advance for the help!

God Bless

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Everyone seems to say gear it down a lot for off-road, but I disagree. Even with the stock gearing the bike works well in most off-road situations, including typical single-track in hilly regions requiring only minimum clutch abuse (believe me, a lot of the gearing issues are due to rider experience, not the bike). The stock sprocket on my 08 was a faulty design, it didn't let the chain ride low enough to get full bearing, so I replaced it with a 44 tooth renthal. With a 44 your speedometer is still close enough to gauge how fast you're going, and you still get good highway speed, and the acceleration difference is noticeable. With a 44 you don't have to buy a new chain either. For most off-road applications, first gear is low enough stock, much lower than an MX'r, for example, and the gear spacings aren't particularly wide for upshifting. I rode my stock geared 08 on a single-track loop most riders wouldn't attempt, and although I had to abuse the clutch some, there wasn't much that the stock first gear wasn't low enough for - most problems I had were related to the rider hanging on rather than controlling the bike... LOL -

If your bike is new, you'll find that the low-to-mid torque will increase very noticeably as you get more hours on it during engine break in. This bike is not underpowered IMO, it just needs to be spun at higher rpms to get to that max power. I could best somewhat less experienced riders on a TT track with my stock bike, and they were on MX'rs - on the TT track I could ride it like a 125. It is not a wheely machine, but so what. There's a good chance you'll be happier with the stock power as you get more riding time on it, I was, and I'm used to high horsepower machines.

This is an outstanding dual sport.

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Well shoot. now ya got me wondering if I should even change it or not. Im a former mx racer. I raced a 08 kawi 250F in B class. The WR seems to be really doggy. although I havent reved it out. it only has 780 miles on it. So Its pretty much still new. Maybe I could leave the rear sprocket alone and just switch out the front sprocket to a 12t and just use it when I know ill be riding off road. I found one on ebay for 11 bucks. but it says its for a yz 250F

Will this fit on my WR 250R? Its cheap enough. 11 bucks plus shipping. if you guys tell me it will fit, im ordering it. Im going with the 12/45 for trail riding and 13/45 for road.

http://cgi.ebay.com/ebaymotors/Yamaha-YZ250F-YZ-250F-12-Tooth-More-Power-Frnt-Sprocket-_W0QQcmdZViewItemQQhashZitem1c1081cd63QQitemZ120536026467QQptZMotorcyclesQ5fPartsQ5fAccessories

Will that even fit?

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I disagree.

I feel the bike comes geared way too tall (on purpose, I do believe, in order to pass some kind of drive-by sound test).

If not for that, I'd bet a million that it wouldn't come with such tall gearing.

Around here, a trail rider would be gearing it down to make second and third gears usable out on the trails we have.

When I first rode mine when it was all stock, I wanted to throw up, it felt so plugged-up.

Doing the usual mods and putting on 12/47 sprockets made the bike very nice.

As long as that EBay sprocket fits a YZ-250F, it'll fit your WR-250R.

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I have played with gearing a bit, having a two wheelset one for off and one for onroad.

12-52 is suitable for playing with bike, trying some trial issues very slow balancing and this also good when riding a snow groove in woods, this helps me to ride with 3th gear.

12 front is not good for anything else, "chain speed" will be too much, said my prof friend ­čśĆ.

13-43 is good for driving onroad

14-43 even bit better if you are on highway or like higher speeds.

13-52 is good for offroad enduro.

But now i'am back to stock gearing, don't need to change front sprocket when change wheels.

Suggest: 13-43/52

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Would a 13/52 be the same as a 12/43? I was thinking if I left the rear stock sprocket on, I could just switch out the driver gear from a 13 to a 12

12/43 is roughly the equivalent of 13/47. I ran 12/43 for a while but the 12-tooth sprocket wore out rather quickly. I'm now at 13/48 and it's pretty much perfect for my tastes. Creeps well in 1st gear and still does 70 mph on the highway without trouble.

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I just figured it would be easier to switch the front sprocket on and off. Their about 16 bucks at the local dealer

The only problem with that is the countershaft nut is supposed to be replaced every time it's removed. It has a sleeve that crimps into indentations in the countershaft to keep it from moving. I suppose if you don't crimp it you could reuse it, but you would increase the risk of spinning it off at speed.

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Crimp that sleeve gently. When opening the nut, use small flathead screwdriver to "open" the crimp.

And if you are using same manufacturer front sprocket the crimp will be done alltime at same position.

Scratch a mark on countershaft and nut, so you can see if it start to turn out.

I have released front sprocket at least 20 times and with no problem, but i

will buy new nut in near future ­čśĆ

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  • 2 weeks later...

I live in an area that has a lot of very steep, very loose rock trails. I can't use the engine for braking on some of the downhill parts as I will be slower than stall speed in 1st. Because of this, when I wear out the original tires and switch to D606s, I intend to change the gearing as well. I find 1st too tall some of the time. I am reluctant to install a 12T front, although many do it, as it not only has a short(ish) life, but is murder on the chain as well. Stock gearing is about 3.3:1, I intend to go to about 3.6:1, not only for the steep trails, but also because the D606 tires are taller as well. I have considered, and probably will go to 14/51. That will give me a better chain/sprocket life than anything else that is reasonable.

Note: I have done this on almost every off road bike, and quite a few street bikes since the 60s, and while I'm sure your way works for you, I've never had a smaller front sprocket give me better chain/sprocket life. Please don't try and convert me, I just favor going to the largest reasonable front sprocket. If I were a competition rider, and considered high sprocket replacement a cost of competition, I wouldn't care. As I ride for personal enjoyment, sprocket and chain life is important to me.

As for power, I find it has more than it feels like. The delivery isn't as frantic as a two-stroke, or a 450. But I found that if I paid attention, I was actually building a lot more velocity than perception indicated.

Hope this helps....

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Has anyone tried to change the gears in the transmission rather than just swapping sprockets. I ride 13/46 which i think is a pretty good compromise for commuting and offroading. When i do go off roading, i have about 30 miles of highway to go before i hit some trails and ideally i would like to keep the gearing as is in 1st through 4th but then lengthen out 5 and 6 to get better highway speeds. Its 30 miles of pretty much straigh tarmac so if it takes a little bit longer to reach top speed then so be it.

Are there aftermarket components for the WR gearbox to change some of the ratios?

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