Where can i find these smaller sprockets?

I want more speed for my bike, but all i can find on the web is a 36t rear sprocket. I read about 32t and 28t sprockets that people put on their bike to achieve 40 mph+. Where can i buy these smaller sprockets?

 

[Alaskavan]

I got my sprockets from Kings Sales and Service, but there are limits to how much speed you can get from a 2hp motor. I'm running more than 2hp.

Oops... Looks like someone may have hacked his site.

 

[oologah]

Have you tried the 36t yet? With an out of the box 2 stroke you will really be bogging the engine going up a medium hill. I'd get a expansion chamber muffler first cause you'll need the extra power to pull the smaller sprocket. I got the Spooky Tooth one, it boosted my speed about 4 mph on the hills w/ a 44t and after riding 1700 miles in 3 months I'm happy cruising at 30 mph.
I may go with a 40t cause I don't think it will hurt my take off too much.

 

[JimKamenidis]

I think the shift kit will help you as much