13-45 ftw

 

Check this place:
Kawasaki KLX250S Parts, Performance, & Accessories - ProCycle

 

Main difference I see is that the 09+ sprockets have a thicker flange that the earlier bikes dont use. The spline size is the same but you may need a washer to make up the thickness.

 

I ordered at 13T from Rocky Mountain. Thanks for the link, I'll order a 15 from them plus that mixture screw now I know where to buy it!

 

i just used the 15T sprocket because i had to make a 200 mile trip.

i was very happy because i thought that the bike's performance would die, but seems my 1995 klx250 (mcm only to the inlet, exhaust, dj kit, cam, ported head, 11,8CR) has enough power to manage the long gears. Of course its not well for dirt riding

 

with the 14 I have currently, I think it's lower than need be in 1st gear. That's with deep mud, rocky technical stuff and what not. Granted I'm sure there is rougher trails to be had, but I tend to use momentum enough that 1st is just that tad bit low. I certainly would never install the 13 tooth because of this.

I also commute around on the bike enough that I've strongly considered putting a 15t up front. The only reason I won't is because the front wheel is just lofty enough with the 331 kit, I'd hate to lose that.

 

I think the KLX will be ok with a 15T. Definitely not ideal for dirt but I agree will the momentum thing. I find my self using second quite a bit while riding dirt. I do some pretty technical riding some times and I use first less often than I realize. Honestly if the suspension is up to the task a little momentum makes things easier to manage. I still look forward to running the 13T for dirt, I hope it gives the bike a little edge and snap when needed. I might slap that **** on tomorrow and try it out before I go desert riding next week. Honestly the spread Kawi has on the gears is real nice 90 percent of the time with the 14T. I'm hoping a 15T will make it a pinch less revvy on my long highway runs. Ultimately I'll run a big bore too. Hoping I can manage some "adventure" rides with camping gear. Just sucks because any decent camping or dirt anything is a two hour freeway ride from the bay area. For those of you who haven't driven in California the norm is 10-15 over the posted speed limit, which sucks for the little KLX on the highway.

 

Does the SF have smaller wheels? That affects your final ratio. the overall impact is similar to making shorter gearing, so moving to a 15T on an SF has less impact than moving to a 15T on an S. HTH.

I drive 90% dirt and tight trails, 10% road, so the shorter gears (13/42) suit my inner rockcrawler spirit better. I have a 48T rear I'm thinking of putting on, but I think I would move back to the 14 front if I did that. A good rule of thumb is "One tooth in the front is about the same as 3 teeth in the back: 14/42 = 13/39 = 15/45 = 3.00." I haven't had the 13T off road yet, but I need much less clutch getting into first from a stop already, so I'm optimistic. I think 14/48 is going to be overly aggressive, but time will tell.

 

Yes, the SF does have a slightly smaller rear wheel (17" on the SF vs 18" on the S) but the SF comes with the smaller rear sprocket (39T on the SF vs 42T on the S) to compensate. I suspect the final drive ratio of each bike, at least when stock, is very close, and the impact of the 15T on final gearing in relation to rear wheel size should be (nearly) imperceptible.

 

I will say if you want more highway capability in the 65-75 mph range the 15 will help. I'm running a 15/39 and it doesn't take much to get rolling for road use. I am in 5th around 50-55 mph, using 6th above that. I don't let it drop under 5000 rpm when open road riding. Acceleration down low sucks, but that is the price of using tall gears. If all I did was road riding I'd stay with the 15/39 and live with the lousy low range acceleration and no wheelies that come with it. The bike can still out do most automobiles.

I will go to a 13 eventually to allow some light trails and have a 47 rear for serious off road.