Since my two local shops are unable to install a 15 tooth front sprocket. I have to change my rear. So my question is, if I go to a 43 tooth rear sprocket will that do the same as going to a 15 in the front? Or would I need to go to a 42?

Since my two local shops are unable to install a 15 tooth front sprocket. I have to change my rear. So my question is, if I go to a 43 tooth rear sprocket will that do the same as going to a 15 in the front? Or would I need to go to a 42?

http://faq.ninja250.org/wiki/Changing_gearing_J_bike

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

14/45 (stock) = 3.21
14/44 = 3.14
14/43 = 3.07
14/42 = 15/45 = 3.00

You may need to shorten your chain.

Again, you are following the wrong path for no reason, just bad advise.

The bigger the smallest sprocket, the less stress on the chain.

.... if I go to a 43 tooth rear sprocket will that do the same as going to a 15 in the front? Or would I need to go to a 42?

15/45 has the same ratio as 14/42.

You're missing the point. Avoid both shops that are feeding you crap. Heck, there is a DIY thread at the top of our tech section that can walk you through installing the correct 15 tooth up front.

Standard set up is 14/45, I think I will eventually be going up one tooth to 15 on the engine sprocket for my 2012 ninja 250.

No reasons why there should be any problem doing that.

Since my two local shops are unable to install a 15 tooth front sprocket.

/pulls up a chair

WTF? I gotta hear the reason for this.

http://www.smugmug.com/photos/i-GpkZsHX/0/O/i-GpkZsHX.gif

I tried a 15 tooth sprocket, but found that I didn't like the increased vibration. The stock counter sprocket has a rubber insert that helps isolate vibration. I went back to the stock sprocket and instead changed to a 41 tooth rear sprocket. I had to remove 3 chain links, as I remember.

To each their own. :2cents:

I tried a 15 tooth sprocket, but found that I didn't like the increased vibration. The stock counter sprocket has a rubber insert that helps isolate vibration. I went back to the stock sprocket and instead changed to a 41 tooth rear sprocket. I had to remove 3 chain links, as I remember.

Yep, I noticed the rubber bushing the first time I removed the sprocket. While I do like that, it's something that you're gunna have to come to terms with, as the stock one doesn't last forever. Of course you could get used fronts but better stock up now. There are other solutions to the vibration problem anyway.

Interesting note, I like the stock gearing on a pregen vs. 15/45 on a new gen. Go figger', never really thought about it. :idunno: