Re: need for speed
I agree... you'll need to run in your engine really good and it'll be faster after 300 miles or so... Then you can think about expermenting with sprocket sizes depending on your weight and how many hills are in your area... a 36 tooth will make the bike faster, but it'll also slow down it's acceleration and climbing ability considerably. The 44 tooth will give you good climb and acceleration with a moderate top speed, but it's still capable of pushing you above 40mph with sime mild engine upgrades like a good pipe, the proper carb tune, better compression by using a Puch Hi Hi head or Fred Head, and some mild porting, You can also buy a ported jug from several of the vendors in here like Arrow Racing, Fred at CRmachine.com, Jake's, and a few others, don't fall for those so called high performance jugs sold on ebay for under $40 because they're the same thing you already got, get one from a reputable builder like those mentioned and you'll be happy.
You will need to break in your engine all over again if you buy a new ported jug but you can remove yours after break in and port it yourself if you got the ability to, or buy a ported one and break in the engine again.
With these upgrades you should be able to hit around 40mph with the 44 tooth sprocket and still have excellent acceleration, or even faster with a smaller sprocket with decent acceleration... There's a lot of hype going on with these engine upgrades so beware of what you buy and go more for the stuff that counts like compression, pipe, and porting as even a stock NT carb and stock CDI will still get you up to the speeds you're looking for