Finally got around to counting the teeth on my sprocket last week and found the front one had 13(didnt initially count the rear). Knowing that I dont feel the need for crazy low end torque and would rather see better performance in top end I went ahead and ordered a 14 tooth to start and figured on a 15 down the road. 14 came in and got installed so I counted the rear while the chain was off and realized it was a 39. Knowing that the stock set up was 14-42(I think) should I go back to that or is there something better? Is 14/39 a particularly good or bad set up? Runs great still and seems to run at a slightly lower RPM at higher speeds than with the 13. Any thoughts or suggestions?

 

I thought the stock rear on an sf model was 39, with front 14. Stock on the s model is 42.

If it works for you, go with it! There's no general good or bad in gearing. It all depends on the rider and where/how you're riding. I'm running 13/45. Pretty sure that wouldn't work well for you.

 

You are correct, since the sf and s have different wheel sizes the s comes with 42 and the sf with the 39, final gear ratio is the same.

 

The standard 250 SF will battle to pull a 15/39 setup. I used a 15 on my 331. Was cool, but went back to 14/39.

 

I need to do this, I never changed my 13/39 gearing and unless you plan to do trails, never go so low with a big bore kit, imho the gears seem super short and you get into 6th around 40mph (otherwise your bouncing off the limiter and the big bore doesn't make much power there)

 

Thanks for the input. So far I have been digging the 14/39 set up. I have noticed a little more sound coming from what I think to be the front sprocket. The teeth on the 13 that was on it were worn down pretty good. Any chance the noise I am hearing could just be the new sprocket engaging with the chain a little different?

 

Did you remember to put the front sprocket cover back on? :P

Make sure you chain is oiled, other than that a little noise from the front sprocket is normal- I notice more noise from the final drive when I'm left lane next to the highway divider or driving past a bus- noise reflects higher I guess

Not a concern IMO

 

Worn/stretched chain on fresh sprocket could be noisy.

 

the rubber on the OEM front was just for the noise, new after market stuff has no rubber for damping the sound.

 

I cant say I remember exactly but will look when I get home.....but I dont think there was any rubber on the 13t I pulled off. I suppose it could be a worn/stretched chain but the bike only has 5,000 miles on it and doesnt appear that they were very "hard" miles. Do these bikes come stock with O-ring chains?