Hey, I also live in AZ. I'm located in Mesa. 49cc 4 stroke will get you up to 35mph with a 41 tooth. I'm not sure what you have is 4 stroke or 2 stroke. I've never had 4 stroke before, but my friend who has the honda friction drive 4 stroke didn't have an exhaust pipe, so I'm guessing it's 2 stroke. You'll get 1/2 more horse power with an expansion chamber like this one.
it'll probably get you to somewhere around 38mph with 36 tooth sprocket.
But if you don't have a license, the law won't let you drive your bike at a speed higher than 20 mph on bikelanes. And anything over 30mph on a bicycle isn't even worth it.
I have a 66cc and got to 45mph with an expansion chamber, 27 tooth sprocket,the 66cc flying horse optimized carburetor from spookytooth and the Octane booster on my fuel mix.
I realized later that bicycles aren't meant to handle that kind of speed or vibration after doing all that stuff. I had to constantly tighten every bolt and torque after coming back home from each rides. Trust me it's not even worth it.
Also, 49cc motorbikes that goes under 20mph or somewhere around that speed are sidewalk legal in phoenix. (since the law lets you go on everywhere bicycles can go on a motorbike, you can go on sidewalks as long as there's no bikelane)
Even at 20mph and stopping at every crosswalks, you still can get to places faster than bus or lightrail since you don't have to wait and you can also take the most direct route.
After learning about all this I ended up getting rid of my 66cc and mounting a 49cc and put on a 44 tooth sprocket. I also bought a full face bmx helmet like this one
You can get one used for somewhere around 50~60 bucks on craigslist and wearing a fullface helmet like this will make you practically invisible to cops for some reason.
I tried riding on the wrong side of the road on a sidewalk at 23mph and passed through 3 police cruisers and non stopped to bug me when they constantly bugged me when I was wearing a regular bicycle helmet. This is a good investment