Info on Gear Ratios:

Front Back Ratio Comment
13 42 3.23
13 45 3.46
14 42 3.00 Stock
14 43 3.07 Works with stock chain
14 44 3.14
14 45 3.21
14 46 3.29
14 47 3.36
14 48 3.43 48 is the largest size the chain guard works with
14 49 3.50


13 tooth sprocket Info:

Brand Part # Notes
Sprocket Specialists 564-13 Slightly different shoulder but works fine
Sprocket Specialists 514XK-13
JT Sprockets JT516-13 NOT: JTF565.13; Fits: KLR650 87-89, EL250E 90-93, EX250 86-87"
PBI PO-45
Sunstar 34113 Fit: Kawasaki 1996 EX250-F 250, Kawasaki EL250-B '88-'89 (PartsCanada 2004 mc catalog)"
Kimpex 101006 Equivalent to Sunstar Part # 34113

 

Just to clarify for any one who needs to know - To gear a bike down you have to go smaller on the front sprocket and/or larger on the rear sprocket. One tooth smaller on the front is approximately equivalent to three larger on the rear. Stock setup is 14 tooth front and 42 tooth rear.
I started with a 13 tooth front sprocket. Chain noise seemed a little excessive on the occasional highway sprint to the next trail (chain has more lash due to smaller diameter ie. tighter turn). I am now running the stock 14 tooth countershaft sprocket, (it has rubber chain noise damping collars on both sides), with a 48 tooth rear for even more low end. I purchased a "Primary Drive" rear steel sprocket for the KLX300; $19.00 at www.rockymountainatvmc.com - Part # K1103SR. I believe the 48 is the largest rear sprocket that you can use with the stock chain guard and guides. I am using a 110 link chain "Primary Drive" 520 RDO O-Ring also purchased at www.rockymountainatvmc.com for about $41.00 - Part # PDR520110. "Primary Drive" is the manufacturer.
This setup is great for me here in the Rockies at 7000 ft. I do 95% fire roads and trails but can still do a highway sprint to the next National Forest Access road/trail maintaining 60-65 mph at 6900 to 7000 rpm's, and I can maintain that speed even on the grades.

 

The Kawasaki p/n for the 45 tooth KLX300 sprocket is 42041-1413

 

Wow, this thread has better info than the "Common part numbers" sticky... This should be linked from the sticky so it's not lost.

 

Will the 45 tooth klx300 sprocket fit with the stock front sprocket and stock chain ? Is the stock chain long enough? I was hoping to change gearing without getting that chain noise everyone is talking about ( i do about 50 percent road riding) Is it really that loud.

 

dmar, I think that the verdict is that if you up the rear sprocket to a 45 then you are going to need a new chain (108 links, I think). I don't have direct experience here because I have yet to do the rear sprocket & chain. I will probably order both today as a matter of fact.

As for the noise from the 13T front sprocket, I have not noticed any at all. Maybe I don't know exactly what to listen for, but I have not noticed any unusual noises since I swapped my 14T stock for the 13T Sunstar. If you want a decent gain on the cheap, then I would recommend you just swap the front sprocket and go with it. I have been running that way for about 2 months (1300 miles), and have really like it. I am only doing the rear sprocket & chain to help me get the front end up a bit easier when I want to wheelie over something on the trail.

On a related note, one place that I was wanting to get the sprocket/chain from www.rockymountainatv.com. I like dealing with these folks, but I am not finding the 45T rear there in their Power Drive line. I was hoping to be able to get it in that brand because the sprocket is only like $19 for the other tooth counts. Does anyone know of another source for good quality steel (i.e., cheap) sprockets. The aluminum ones are about $45 or $50 wherever I vind them.

Thanks,,
Chris

 

I'd say you will need a longer chain for the 45 tooth rear. Guessing 108 links

 

This should be helpful to calculate gearing changes.

http://www.dropbears.com/u/utilities/sprocket.htm

 

Just replaced the rear sprocket and chain. Rear sprocket is 45 t (jtr460.45t) chain is d.i.d. part 520v-120L o-ring chain. I used a grinder to remove extra links on chain. The sprocket is the same sprocket for the klx300. I also greased the axle with some of the moly grease I got at my local dealer (about $7). This gave the bike more low end without taking much from top end. Here's a pic or the sprocket. I still have the stock 14t front sprocket . I was going to put on the 13t front sprocket but looked like the chain could possibly hit the gear housing. Plus leaving the front sprocket will keep things more quiet, due to the rubber ring on the stock front sprocket. I got what I wanted, more low end with 14/45 gearing.

[IMG]local://upfiles/2770/CEDCA25948444740AD3E33106CE8C0E2.jpg[/IMG]

 

New to the fourm have been reading for a while now if anyone out there has an oem exhaust that will fit my 06 250 please contact me Ryan
stacie_shadow@hotmail.com
(207)-543-5095