I was to talking to a buddy last night about my decision to go to a 47 tooth rear sprocket. I am currently running a 13/42. He said that might be too much and that I would lose too much of 1st gear.
I ride only in the dirt. Last month I did an enduro and on the single track I found that my speed in 1st was too slow and second was too much with no torque at the bottom end (rpms) of 2nd. This leaves me to believe that I need to get into second sooner and use the full range of rpms in that gear. Make sense?
Who is running 13/47 and what do you think?

 

I ran 14/47 and thought it was great on the trail. It made 2nd gear much more trail friendly. Will be going 13/47 as soon as my chainring gets here.
I think you'll like it.

 

I have the big bore kit, when I had my 13/39 ( 13/42 equivalent for an 18") it was pretty good in the dirt, a little too tall, then I went to stock gearing, 14/39 and while good on the street, it really really really took a hit in the dirt. If I were you I would go with a 13/45 combo, that will make 1st gear usable, but more of a crawler, and where you would use 1st gear at those higher rpms, you can now use 2nd gear to chug a long without being at the point of stalling. If that makes sense

 

I had 13/48 and it made 2nd a great gear. You can start easily in 2nd, but if you need some good lugging you can bump down to 1st. Real good for slower trail riding.

On the other hand 55mph is about 7.5k rpm.

 

I've been running the 13/47 gearing for some time now. For decent off roading I'd never go back to taller gearing. I've been in the desert areas of the Big Bend area of Texas for the past two weeks, and there was no loose climb that couldn't easily be tackled in either first or second gear as needed. I found that 14/42 was too tall for sketchy climbs, period. I found the 14/47 was reasonably adequate, but I often had to hit things with a bit too much speed to easily clear loose, sketchy climbs. With 13/47 second gear sketchy climbs are usually attainable, but when everything goes to pot, I can still go to first and tractor up almost any climb...with enough left over umph to even clear ledges at the top of a climb. The 13/47 gearing on my bike is basically like the 14/50 OEM gearing on the off road only KLX300. It's no wonder it works so well off road.

 

13/47 it is. Thanks. TNC: how about that link count. I think 110 will do?

 

Pretty sure you can do 108, it puts the wheel almost fully forward in the adjustment range though.

 

Went with the 13/47 gearing myself about 6 months ago. Love it on the single tracks here in the hardwood forests of the Shawnee National. It has all the advantages listed in previous posts, but you will notice a lower top speed on the road. I went from a comfortable top speed of 70 mph down to 60 mph with the 13/47 gearing @ a rpm of about 7K. I try to stay off the hard roads anyway and do not miss the extra mph.

 

I've ridden with 14/47 since only a few months after I got the bike. Love it. Unfortunately the closest singletrack is closed... so we do a lot of fire breaks and doubletrack / ATV trails. But it was more than low enough for super tight stuff and I can still cruise at 55mph. Its not fun, but when is 55mph ever fun on a KLX250? I have two new 14t / 47t sprockets and a gold chain waiting to go on the bike in the spring... it'll be my third set.

 

I have added racks and bags and a few other things but the only "modification" I have made is going to 13/48. For my use it is perfect but it's too slow for riding on the highway. I agree with pretty much everything stated above. I use this only on dirt. I would have bought a pure dirt bike but I have to have a licensed vehicle for forest service roads in the mountains. Off the dirt roads and on the trails around Mt. Rainier and Capital Forest areas it still does fantastic for a heavily laden 250. I have swapped back to 14 front for travel to the trails and then swapped to the 13 for riding the trails but decided I would rather trailer the bike to the trails and use my van for recovery and triage after my inevitable crash. I also went with a better o-ring chain but haven't found a lubricant yet that I am happy with. They all seem like sticky dirt magnets that make me think they are doing as much harm as good. I have to clean the chain every time I get it in the dirt. I suppose I should do that anyway. What lube will you be using on the gold chain?