Is it true that if you go 2 teeth down in the front it will put too much strain on your motor?

 

No. If you go 2 teeth down in front it gives the bike more power in all gears at the expense of speed. It gives your motor more leverage against the rear tire in any gear but your speedo will be off. You will now be going slower than what it says.

Just don't overrev the engine and the sprocket won't hurt a thing.