If i change my sprocket to get more power will i have to shorten my chain?

 

Yes, you will need to shorten the chain. Please note that some models also encounter issues with the clearance between the chain and the swingarm when performing this swap. Make certain the chain will clear the swingarm at a lower position (a 12t sprocket will be considerably smaller in diameter), and you may also want to order a half link to ensure adequate adjustment. Most 12T sprockets will also require a modification to your existing retaining ring to keep it in place, but this is an easy task to complete. We would be happy to assist you in ordering the correct parts if needed, we have a large selection of parts for Chinese products.

 

thanks. how exactly do i shorten the chain?

 

Assuming you do not have a chain breaker, you can grind away the head of the pin that links your chain together, then separate the link to remove the unused portion.

Here's a link to a video showing you the procedure, it definitely lacks professionalism but will point you in the right direction ...
YouTube - How to remove a link out of a chain

Good luck !