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YZ250X gearing

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Every review of the YZ250X says 1st and 2nd gear are a bit high.  They say to change those 2 gears so they're lower.  Wouldn't it be easier to just put a bigger sprocket on the back?

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First and second are not too high unless all you ride is really tight walking-pace type stuff.  Personally I think a bigger rear sprocket would make third gear way too short, it's already pretty short as-is

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1 hour ago, dcdr said:

First and second are not too high unless all you ride is really tight walking-pace type stuff.  Personally I think a bigger rear sprocket would make third gear way too short, it's already pretty short as-is

That's right, but with 14/50 the gap from 3rd to 4th is huge. I switched back to 13/49 after trying 14/50.

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I run 14-51 and I think it's perfect for anything East of the Mississippi . You can run tight Harescrambles or fast GNCC style stuff . 

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It's a common strategy of woods riders to add teeth to the rear to get a lower first gear ratio.  That of course changes all the gears however, and may make them too close together.  I've ridden some bikes where the owner has gone too far.  You almost need to skip gears on more open trails because it seems like you are shifting every ten feet!

KTM offers the best variety of gearboxes for various condition.  It has varied over the years, but generally the widest ratio spread is offered on the XCW, and the SX has the typical close ratio MX transmission.  The XC is usually in between.  Also, I'm not sure when it started (maybe 10 years ago?), the offroad models have gotten six speeds giving even more flexibility.

I think Yamaha has done the best they can with 5 gears, but it is a common complaint that the X needs a gear similar to the "granny gear" often found on the Euro bikes.  A six speed would probably make everybody happy besides the perpetual complainers.  

Everybody is different, but I've found that on Japanese bikes, stock gearing or adding 1 tooth to the rear works best for me.  But I don't ride a bunch of super tight stuff, and I just slip the clutch when I do.

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I'm running 13 / 50 and it works well for my riding. Mostly single track with some play MX.

Top speed is as fast as I ever want to go in the dirt. My guess is 55 or 60.

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My experience is the X motor pulls the taller gears better than the KTM, I have owned the xc and the W two strokes and not only are those gappy but the motor falls flat on it's face if you lug down to below 50% up a hill, the yz and X will pull out of a lug every time. That and suspension is why......... well my buddy (fellow X owner) said it best, "I am done with KTM". My terrain is steep though, you are either going up a hill or down a hill, not much flat land here.

Edited by RollieW
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Thanks everyone!  Looks like I'll be going up a tooth in the rear and down one up front.  I'm rarely in top gear anyway.

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21 hours ago, trail thumper said:

Every review of the YZ250X says 1st and 2nd gear are a bit high.  They say to change those 2 gears so they're lower.  Wouldn't it be easier to just put a bigger sprocket on the back?

Do yourself a favor and ride one before you change the gearing. I figured changing the final drive gearing would be the first thing I would do when I bought my X. After riding it on some tight single track, the gearing is pretty good. Would having a lower 1st and 2nd be better? Maybe just a little but I don't plan on changing the gearing for my use.

Focus on getting the jetting better and you will be surprised at how well it pulls, especially in the tight stuff. 

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I was a big advocate for 13/50.

I have my squish adjusted, altered powervalve, flywheel weight (eline stator) and yz/yz-x clutch spring combo (3/3).

With these mods, I like 14/50. Same riding area, same trails but a better power delivery now and everything works well together. I can abuse the clutch and the yz springs slow the fade

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2 hours ago, N8ster said:

I was a big advocate for 13/50.

I have my squish adjusted, altered powervalve, flywheel weight (eline stator) and yz/yz-x clutch spring combo (3/3).

With these mods, I like 14/50. Same riding area, same trails but a better power delivery now and everything works well together. I can abuse the clutch and the yz springs slow the fade

Is it really that much difference? Did you raise compression, too? Or just corrected the squish? 

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Squish set and slightly raised compression. It was a combination of everything together, not just reworking the head (msg me if you want the info on my cylinder head).

On the last 2/3 rides with 13/50 I noticed I could leave it in second and make it up tight greasy hills but have to really heat up the clutch to do it. I'm getting more traction in lower rpm but the clutch suffers. This got me thinking about going back to 14 and running first gear in the same areas. 

13/50 was one of the first things I did to this bike and I had 90 hours with it to know how it works. 

A down side to switching back to 14/50 is hitting neutral between 2/1 shifts. This is something it's always done but I'm using first gear more than with 13/50. I'm getting used to just tapping it 2-3 times to make sure it's in first

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I went down 1 tooth on the front and left the back alone.  Enough to make it better at low, low speeds, and very inexpensive.  Try it first before you order a bigger rear sprocket, it might be just what you are looking for.

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That sounds like a good start.  I just don't like going down tight single track and coming around a corner with a decent size tree across the path and just a little too low in the revs.  Has ended up messy a couple of times.  If I was a better rider (and not 54!) I would be going faster. Thanks for the tip.

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Went to my local bike shop and picked up a 12 for half price!  They didn't have a 13 on the shelf.  They will have it in a couple of days.  Thought it would be handy to have a 12 in the tool box just in case we decide to make some new trails. Or I take up trials!

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Haven't changed any gearing at all.  Still getting to know her.  Probably won't ever use it but for $15 might as well have it.  I'll go with the 13 and see how it does first.

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I ran 13/50 on my YZX at St Anthony dunes. It was perfect there and I was able to pull Choke Cherry Hill in 3rd at WOT peak rpm. Off road I run 14/52 and it works great for my local terrain.

BTW gearing is super important in the dunes. Even though they have significantly more HP there were 2 450s in our group that couldn't climb Choke Cherry, and mine was the only 250 2stroke that made it that day. Wheel speed and RPM are everything!

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14/51 seems to work best for me. 14/52 made my bike too jumpy for my taste and required too much shifting. I can't imagine 13/50. I ride eveything from slow first gear tight/ technical trails to fast flowy trails in 4th and 5th gear. I have also changed to a yz250 head and cdi and have done the 3 washer power valve mod. I guess it depends on how fast you ride and your personal preference for gearing. 

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