I have not messed with any sprockets yet, but I would think if you are going to do much riding at 60mph or slightly faster, then you would not want to change the sprocket.
its already doing over 6K at 60mph in stock form.
If you are doing mainly slower speeds, or alot of actual offroading with it, then yes, that sprocket would certainly help.

 

I never did ride my used '06 KLX with the stock gearing. I'm curious on that "over 6K at 60mph comment...not doubting it, just curious. I have a Vapor instrument panel with a speedo input that has been calibrated to true GPS speed. The Vapor tach is quite accurate from what I can tell. My gearing is 14/47 as opposed to OEM 14/42...pretty close to a 12/42 in gearing comparison and that's fairly low. I also run a 100/100/18 rear tire, so it's not a big tire size to affect speed/rpm. At a true 60mph, I'm running 6950 rpm...the Vapor tach has a digital readout down to the even 10 rpm. I can't check the absolute accuracy of the Vapor tach like I can the GPS speed, but I'll can tell it's pretty uniform in its operating range. Is the stock gearing with a generally stock tire size really that high at well over 6K rpm at 60mph? Any of you folks that have or had the stock setup, what were your results?

 

I have the 13-45 sprocket setup, and I do 65 (actually 60 according to the GPS) and the RPM'S run at 7 and it will do it all day. Don't be afraid of rinning the bike up at that range. After all the best spot is 7-8 grand.

 

My bike will still run 80 mph with the 13 tooth on the front so yes you sure can ride at 60 and 70 with it and it is not an issue at all.

 

Gearingcommander says stock 14/42 setup for the 2006 KLX250 should do 60 mph at 5635 RPM; 70 mph at 6570 rpm; 80 mph at 7515 rpm.

With 13/42, 60 mph at 6070 rpm; 70 mph at 7080 rpm; 80 mph at 8090 rpm. It's a good site - check it out (http://www.gearingcommander.com/).

I was running stock a little over a month ago and the commander appeared to be very close if not right on while adjusting for the speedo error - checked with GPS speed and stock tach. Running 14/49 gears now or I would check.

 

is this speedo 80 or GPS 80? you might be surprised if you haven't checked via GPS...just sayin...

 

Doing an indicated 70 mph my sons GPS say 65 mph.

09 KLX250SF stock geraring not that it matters.

David

Soon to be KLX351SF !

 

Im pretty sure my 09 is off allllmost 5 mph at 45 mph
WHY are these bikes like this? Seriously, why would a modern bike be off this bad?
I think its a bit ridiculous. I wouldnt care all that much, but this means its effecting the indicated mileage also. Which means even calculating distance and/or mpg is off.

 

The optimistic speedo is common for the many, many motorcycles I've owned since 1970. On the odometer, however, they are more accurate than the speedo's. The odometer is not dependent on the speedo readout.

 

Think of the optimistic speedo as an anti-speeding ticket safety feature.
My '09 is 10% high compared to GPS.