Join Date: Jan 2012
Location: Bremerton, Washington
Check your rear wheel tension adjustment to see if it happens to be towards the front of the adjustment slot. When you reduce the size of either sprocket, you need to move the rear wheel back to compensate. The smaller the front sprocket, the tighter the chain must wind around it, so there could be slightly faster chain and sprocket wear. And your speedo will be an additional 6% off. It's about 6% off from the factory. Total of 11-12% fast. A speedo healer is needed to get it to read right again. Then, after correcting the speedo, your odometer will be 11-12% off. Or you can install a new adjusted face to your speedometer.
An alternative is to use 17-43 gearing like I do or you can go to 16-42 to keep the stock chain length. No matter which way you gear it down, your speedo or odo will be off. You can't make them both correct. (OK, you can, but why would you bother leaving the gearing stock and changing the speedo face to read correctly.) I don't think anyone makes a face for that situation. New faces for our speedos may no longer be available.
The bike will be more wheelie-prone, but that's just fun, not a problem. Enjoy.