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XR400 drivetrain/gearing

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Stock 15/45 or a touch taller IMO. Take that with a grain of salt as I don't live anywhere near a desert. I'm just assuming most of your riding will be 3rd gear and up. I run 16/47 for dual sporting (15/47 off road trails only) and easily cruise all day at 55 without taxing the motor heavily or it being to "buzzy" from a lot of rpm's. If you get any taller than 16/45 (= 15/42) your just giving up too much power IMO. Stock 108 link chain should cover a wide variety of combos. "O" ring or "X" ring chain.

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I live and ride so cal desert. I run a 14/42 (same as 15/45 stock ratio) but allows me to switch to 15 on the trail if needed on a multi day ride... or to get home. Ride the good stuff out 14/42, ride the fire roads back 15/42. Changing the front sprocket is quick n easy.

I also have a 13t sprocket but have not needed to use it... Maybe this summer in Oregon will give it a try.

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Quick semi related question. Does anyone know if my chain will fit if I go from 16/45 gearing to 16/42. Right now my chain adjusters are on the 6th indention. I'm thinking I'll want some higher gearing for longer trips. Thanks.

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Yeah I did, thanks for asking. The frothy oil was due to not having put enough in after the rebuild. I added more and its all good now. Just got back from Blessing of the bikes in baldwin this weekend. Rode 250miles all around there and had a blast. My friend and I were 2 of 4 dirtbikes we saw at the blessing but it was an awesome time.

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Yes it will. I run everything from 13 42 to 16 42 with the same chain.

Right now, I run 14 42 for dez if Im hauling the bike in the truck. I run 15 42 for dual sport rides with lots of hwy. 13 42 for the tuff stuff.

Quick semi related question. Does anyone know if my chain will fit if I go from 16/45 gearing to 16/42. Right now my chain adjusters are on the 6th indention. I'm thinking I'll want some higher gearing for longer trips. Thanks.

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SHRK, post up your results when you try it. I tried 14/45 to 14/42 and it did not work... ran out of adjustment. All the way back and chain still too loose.

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aDayintheDirt, when you change between the 14 and 15 front is it enough of a differance that you have to readjust your chain?

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Thanks, I figured as much but I was hoping for a two bolt fix for getting to the trail with less RPM's

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SHRK, post up your results when you try it. I tried 14/45 to 14/42 and it did not work... ran out of adjustment. All the way back and chain still too loose.

I got my 42 tooth sprocket on. Running 16/42 now. When I switched from the 45 tooth to the 42 I went from the 6th chain adjuster mark to the 28th mark.

I can cruise at 60-65mph now, 70 is pushing it a bit but doable. I'm around 5500 rpm at 60mph. I topped it at 98mph, but might be able to push it to 100 or more with a longer stretch of open road and better tucking for aerodynamics.

First gear idles around 7-8mph. Pretty high for anything off road. It still takes off just fine though, brings it up in first and second without trying. Easily powers up in third with a little tug. I can't get it up in 4th anymore like I could. But I have been able to do it a couple times. Getting it to the balance point is difficult and when you do there isn't alot of spare power left to keep it there. My mods are listed in the garage if you want to know what engine work I have done.

Hope this helps.

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aDayintheDirt, when you change between the 14 and 15 front is it enough of a differance that you have to readjust your chain?

Yes you will need to adjust your chain.

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