Engine/Frame Question

[clyffcarlock]

I hope this makes sense. What bigger engine can fit on the smallest frame without modification... Example: Can a 250cc engine fit in a 150cc framed scooter. Can a 150cc engine fit into a 50cc framed scooter? Does this make sense?

If modifications are needed, how extensive are the mods. I am thinking of finding a cheap non-working scooter and replace with a new larger faster engine.

If I can find a $100 model off something like Craigslist and purchase and install a new 150cc or 250cc engine, I should have a decent scooter that is durable to do some weekend traveling trips with a second rider without putting too much strain on a smaller engine or even a smaller used engine that may lead to a unexpected break down... Do not want that to happen to my son and I on a weekend trip.

Thanks for any info/advice everyone can give.

P.S. If anyone can give something like a chart/list/ or web link of a break down of the minimum engine to frame size compatibility thank would be fantastic. Thanks once again.

[rockynv]

Even if it fits it may not be wise. Frames are minimally built on many and barely adequate for the intended engine. Then there are the brakes to consider. The brakes on a 50cc frame are generally adequate at 25/35 mph with a single rider but put two people on the bike and ride at speeds up to 65 mph with a 150cc engine in it and you are asking for trouble.

Then there is weight capacity. A 50cc frame has barely enough capacity to carry two riders at 25 mph if you hit a bump in the road and may become incontrolable if you go over a bump at 35 mph so at 55/65 you could be in a lot of trouble having frame failures and loss of control with 2 riders on the bike.

It will be cheaper and safer to just get a used 150 or 250 keeping it as it was designed.