thanks, fairracing! that engine sits pretty high, huh? the bike i bought today is a rusty old Murray which has the two down tubes like that one, but they're curved in such a way that the engine would sit lower.
i think this old bike might make for an interesting build if i got rid of that top tube that was so crappily stuck on it, but i'm still wondering about the strength of the girl bike frame geometry; seems like a triangle missing a leg. wonder if the chances of sudden catastrophic frame failure would be in any higher than on a men's frame if i bolt on a little Morini?
Enter "The Dragon Lady".
I have a girlie cruiser. Her first transplant was a front electric hub running 72vdc and 80lbs of batteries. A very enjoyable ride except for the hassle of charging batteries and carrying the bike up two flights of stairs daily.
I could also FEEL the frame flexing from the excess weight when the cruiser tipped the scales at 135lbs (The bike originally weighed 45lbs).
I moved on to gas engines. I could not fit the Happy Time engine into the 2006 Raleigh Retroglide single-speed frame. So I started with a 2.2hp 43cc Mitsubishi engine w/friction drive and 1.125" roller.
Then I changed to 1.5" roller and an expansion pipe. Top speed was 30mph, rpms over 9,000rpm.
Then I added a SECOND engine up front. It was another 2.2hp Mits engine w/1.25" roller.
Acceleration was awesome! Top speed was now about 36mph with front engine screaming over 11,000rpm.
Front roller changed to 1.375". Acceleration was still very good and speed increased slightly to about 38mph. Engine pushing over redline to 10,000+rpm.
Front roller changed to 1.5" and another expansion pipe added. Acceleration is slightly sluggish but speed increased to 39.3mph. Engine revving to 9400rpm, slightly over redline. Both engines are singing happily.
Side-pull vee-brakes added front and rear, in addition to rear coaster brake. Braking is excellent, even at high speed and riding in traffic at 35mph+.
I have absolutely no problems with my twin-engined girlie cruiser, even though it now weighs 91lbs.