Re: whats the largest 2 and 4 stroke motor your willing to intstall in a bicycle ?
Unless you plan to race or do off road riding, why would anyone want a bicycle to go faster than a simple little 66cc 2 stroke could pull it?
I have four bikes currently, 3 of them will easily do 35 and 2 of them can hit 40+. (I rarely ride them faster than 25)
If I want to go faster than that on two wheels I'll buy a motorcycle; something designed and built to go faster with rims, tires, brakes and bearings meant to take those speeds.
The big problem I have with advocating bigger engines and more power/speed is the potential for an uninformed person to accomplish a big engine install without giving consideration to those other areas of a bike that will make it safe and reliable.
Another factor I see as a down-side to faster motorized bicycles is the negative attention they will surely get from law enforcement. Anyone with a vehicle with lots of power will be prone to use that power and it won't take long for John Law to notice. It certainly won't do our hobby any good. Almost without exception the current laws pertaining to our bikes have speed limits built in. When we start to violate those limits with big CC bikes someone is going to notice and that someone might be the law makers in your state or city.
Age and Treachery Will Always Triumph
Over Youth and Skill & "Charlie Don't Ride"