Already being posted in another thread, so why not.
http://www.fort42.com/gateshark/game14/
Probably works online, I only really want to use 200CC for local multiplayer so I can enjoy the game again with some friends in a different way. However, as I have a US N3DS, local multiplayer for out of region games is disabled. I hope eventually it will get ported to the US version.
Also the problem with those cheats is that you need to restart the game before changing back to normal or another CC. Some other user posted their broken gateway port of the plugin in this thread, but it got nuked. It's cached, but the fixed version he posted a little bit later is not cached. Someone might be able to fix it.
Yeah, I didn't bother to create a code that can fix the speed by using the value 0x41100000 from the pastebin. I tried that and I made the speed seem more normal, but it was not accurate for 50cc, it basically returned to speed that feels like 150cc. So I decided to just leave the codes like that and properly reset to default speeds by turning it off and on again.