Re: Is putting a motor on a RACING BIKE with THIN TIRES dangerous?
You could try a 27" or 700 wheel on the front with some investment and see how you like that first- that's how I approached it
And I liked it so well, I built another with 700c wheels and went back and put a 27 on the back of the other-
Most bikes have a drilling for the front barke- you will need an older medium reach brake- if you have cantilevers that connect to the fork, they will not fit then- save them
measure the reach and be sure to get the right one. Wheels can be had used sometimes on craigslist, but not always when you want them. I've got some that way.
a 27 x 1 /14 is a great size- that translates to about a 32 mm 700c width, but tire manufacturers vary a bit there
Don't recommend necessarily if you plan to ride a lot in the rain- I NEVER do unless caught
but you'll find even with just the front the bike rolls and pedals a lot easier
Other performance enhancers for the older bike might be a bilet intak ($20) and a 415 trike chain which is a lighter 415 chain with smaller plates and much less rolling resistence for the motor too. ($15 shipped) These two things alone might be the difference you seek. I get 30 cruise easily on the 66 with 27 x 1 1/4 and a 34 gear, and 35 plus opening it up- never do.
If the hills are not miles long, a quicker lead in would give you more meomentum too.