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EX 400 1st gear into XR 400

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Hey guy's new hear to Thumpertalk. I have an XR 400 that is dual sported and the tranny just isn't wide enough. The EX has a 2.9:1 First and the XR is 2.6:1 Can I put the EX gear in my XR. If so how complex is the Tranny. I've never been in there but I've worked on just about everything else.

PS You can carry 2 front sprockets with you with the little C clip and switch em real quick if your sick like that, but I'm too lazy.lol

Thank's

Guy's

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Hey guy's new hear to Thumpertalk. I have an XR 400 that is dual sported and the tranny just isn't wide enough. The EX has a 2.9:1 First and the XR is 2.6:1 Can I put the EX gear in my XR. If so how complex is the Tranny. I've never been in there but I've worked on just about everything else.

PS You can carry 2 front sprockets with you with the little C clip and switch em real quick if your sick like that, but I'm too lazy.lol

Thank's

Guy's

I don't know but that's a really good idea...lurker.gif

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+1 on the sprocket C clip issues; if the rear sprocket is not correctly aligned the the front sprocket can slide over and the chain can wear thru the case into an oil gallery (don't ask). I switched back to the Honda lock washer and bolts, never had a problem with the bolts.

The bad news is you gotta split the main cases so add in the cost of a gasket set.

I've done gear ratio swaps among the two valve 185/200 family of engines (XR, TLR, ATC, etc), just check the part fiche to make sure mating parts are the same, although Honda sometimes makes an upgrade that doesn't change fit but does change the part number. Also some Hondas have the 1st speed driving gear as part of the main shaft, which bumps up the cost a bit.

The XR to EX 1st gear change is a big one and will make for a very wide 1-2 gap, adding some more gears from the EX could reduce the gap. Maybe use the entire EX tranny if it has a wider overall spread.

The above is the short summary but the devil is in the details so hopefully a TT member who has done a EX/XR swap will post details.

Edited by chuck4788

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replace the bolts with allen head bolts and you all you need to carry to switch the sprockets is an allen wrench. Put your spare sprocket and allen wrench into a little container and velcro it to the inside of the airbox. Then you have whatever you need with you all the time.

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Thanx for the info, very helpful. Yea hopefully someone who's has done a swap will post also. Sounds like a big job tho, but it really wd be worth it? Your right I should put the 2nd in too, to lessen the diff. from 1-2nd. I ride a wide variety of stuff and lately have been riding on the rock crawling trails at High elev., so I need LOW gearing.

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What we do in Baja if we have too.We use a 16t for the long jeep roads less fuel,oil ,less revs.If we get long single track(im talking 50-100 miles) we change to 13,we did small mod to chain adjuster.So same chain works both gears.

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Why would anyone need a 2.6:1 first gear in the xr 400 lol. If you drop to a 14 tooth on the front, first gear revs out to like 8 mph. I couldn't imagine needing a 2.6:1 on a xr400. Even with a 15 tooth on the front first gear is all revs.

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I have seen this talked about before but do not know if anyone has actually done it. It would be nice to have alittle shorter first gear when your xr400 is dualsported, like I have found out just starting out it is alittle tall, may have to slip the clutch a bit. I have 16/42 gearing. The only thing is with the 400ex all the gears in the trans are smaller gear ratio. I would like to have some more top speed. I can do right around 80-85mph. I am looking to put some supermoto wheels and tires on and would like to know how that is going to change the gearing.

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Interesting idea. Maybe changing out the first 2 or 3 gears to the EX and keeping the rest from the XR.

Why would anyone need a 2.6:1 first gear in the xr 400 lol. If you drop to a 14 tooth on the front, first gear revs out to like 8 mph. I couldn't imagine needing a 2.6:1 on a xr400. Even with a 15 tooth on the front first gear is all revs.

Maybe that's the difference between Michigan and the mountains of the west. I have had the need for a "granny gear" for rock crawling uphill or through a stream in some nasty areas only to have it open up in a couple hundred yards for a mile or so of high mountain plateau that is 5th gear pinned riding, then have it dump you right back into the crazy rock crawling again.

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mtn goat, makes sense if you are climbing up rocky mountains and such to have a super low gear. In Michigan I haven't been anywhere that would require a super low first gear.

kfngrn, I have wanted to try that 42 sprocket on the back myself. I have a 16T on the front and a 45 on the rear right now. You should be able to go faster than 80-85 with that 16/42 gearing though. I hit 83 with a 15/45. I haven't tried the 16/45 top speed yet. I would think that with a 16/42 gear you should hit at least upper 80's-90mph if the engine has the power to pull it up to that speed with that gearing. You just have to pin it till the valves blow through the side of the engine to get to that speed lol.

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Your idea of the ex frist gear would be great.We have the same problem in Baja.I have to run the 16-45 on my 440.Than when rock climbing I need a low gear.For us its a matter of 100 mile single track,than we need high gears to bail out on highway before dark.Wish somebody would know if you can do that.

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I have a 16T on the front and a 45 on the rear right now. You should be able to go faster than 80-85 with that 16/42 gearing though. I hit 83 with a 15/45. I haven't tried the 16/45 top speed yet. I would think that with a 16/42 gear you should hit at least upper 80's-90mph if the engine has the power to pull it up to that speed with that gearing. You just have to pin it till the valves blow through the side of the engine to get to that speed lol.

Well I have never opened it up on the high way just the back roads and thats about all I get before I have to start slowing down for the corners :bonk:

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