You should take a look at this thread. It seems it is still a dark area in Pennsylvania with no statures or laws in place to govern them in regards to license, registration, and insurance. I am in Wisconsin and there are statures that specifically define a motorized bicycle and requirements of that bike.
http://motoredbikes.com/threads/pennsylvania-law-regarding-motorized-bicycles.23104/page-4
Also, electric and gas are very different. An electric bike is generally more expensive due to the battery (kit = $200, battery = ~$400). Gas is a more price conscious way to go but I think you need to go automatic in Pennsylvania which means a $220+ kit.
Research this very thoroughly and don't rely on what others say.
Don't rely on what others say? Doesn't seem very forum like, as far as what forums were made for.
OK so I'm in Allentown PA, not super far from Pittsburgh, as far as city "attitudes" go. Now I'll say this, local police in my area have a ton, and I mean a TON, of crap they are supposed to be dealing with, whether drugs, gangs, murder, double parkers, whatever. Now Pittsburg isn't the city of angels, but it's also not a city OF angels. Likelihood of your local pd having more important crimes to deal with is very likely.
Look around, how often do you see motorized bicycles around town, if is around once or twice a week at least then it's a fair bet the legal status is on the back burner, and the police do not have time for petty traffic stops. Around here you are basically left alone, maybe even some compliments if the bike looks cool enough, by the police.
In PA, it is a Grey area with one definite legal requirement, you need a driver's license. You could get away with a permit maybe, claim that a bike is only large enough for a single person, so obviously can't bring a second pair of eyes. Claim the engine is only 49cc if it's 66, remember that they can't prove it's 66 unless they open it up and measure the innards, but that would require a search warrant. Be AS POLITE AS HUMANLY POSSIBLE! Nothing screams arrest me like being an ass hole to a cop, wrong or right.
Remember we live in a Commonwealth and getting your bike back from the impound means you need to prove it's legal, and if you don't need to then have fun with the runaround. Put mirrors on the bike, cops like that, invest in a good set of lights, the little red blinking led just says you were too cheap to make yourself visible, same goes for that also cheap headlight duct taped to the handlebars. Invest wisely, if it looks like you take the precautions to remain safe in all environments, day night, including not going up the wrong way, not driving like an effing maniac on Crack, not speeding through red lights or stop signs, you know, following the general rules and being aware of other drivers, driving defensively, then they don't want to pull you over, remember they get promoted for killing crime, not pulling over questionable forms of transportation, they can't even brag about pulling over a motorized bike.
Sorry about that long run paragraph, anyways there's more. So if you get pulled over, do not play the stupid card, trust me they hear it 50 times a day every day, from everyone. You say that as far as you can tell, along with every other motorized bicycle rider you've met in person and online, in/from PA, are nearly certain that it is in the Grey area, except for needing a license. If you have to, mention or even present the case in Erie, a test case, that determined motorized bicycles are legal. Also definitely state that they are just trying to do their jobs as police, and you understand that, and when they went to pull you over you pulled over, not like some of the idiots who just try to run off by Escaping up a one way road.
If you can, install turn signals, they like the fact that you can signal your intentions on the road, meaning you are way less likely to get turned into road pizza.
I've been pulled over once, it was 5:30 am, dark, drove right past them, and my electrical system was dead, so my lights weren't proper, and I had the cheap lamp on the bars with duct tape. That's it. Really it was, I was kind, stood my ground, very specifically pointed out I was of no threat and pulled over immediately after they signaled me to do so, turned off the engine and waited. They let me "pedal away untill they were out of the area" which is what I did, and started the engine up after they took a turn down a road, and I made it to work on time.
But don't rely on what I said, research everything first, then, if you you feel comfortable, only then listen to me. (I've raced a cop one time to the end of a road, he obviously won, but goes to show that making yourself out to be a problem isn't as benefitial as making yourself out to be a trustworthy, or responsible at the least, individual.
Ride safe, be careful, and wear a helmet for crying out loud. Oh I'll mention I also wore a helmet during that encounter, took it off as well as soon as I turned off the bike, because it's simple courtesy.
