Anybody shopping around for a motor might get very confused by quotes he gets from different shops. You can spend anything from $500 for a wrecker lucky dip motor to $10,000 for a high performance motor with all the shiny bits.
It all gets very confusing when you ring around for prices and for the non mechanics it is hard to say, "This is what I want." I used to play with beach buggies in my younger years and we used to buy Motors off the wreckers. Anything from 1300cc to 1600cc and some even lasted for a while. But if you like a reliable Trike and hate pulling out motors or bits of it, the only way to go is buying a rebuilt motor, a brand new motor or to get one built from new components to what you want. The standard 1600cc twin port motor can be bought brand new for about $3500 and you have to decide what you want to spend on shiny bits to make it look good which can cost you another $2500.
If you would like something with a bit more grunt to be able to lose some bikes on the road while heading uphill, you need a custom performance motor. Done right, they will last just as long as a standard 1600. To add to the confusion a 1776 motor can go better than a 1915 or visa versa. It all depends on the bits inside the motor.
The best way to make a decision here is to ride other Triker's toys and see how different they go.
There are still stories going around that a Beetle runs on a wet rag. Those stories are coming from the times when everybody drove a V8 or 6 cylinder and talked to VW people in a 1200cc. Anything bigger than that uses between 8L and 15L of petrol/100km and is very much dependent on what you do with your throttle. Put very simply, the handle that makes the Trikes go harder makes the petrol run faster.
I have been cruising back from Melbourne never going faster than 100km/h and most of the time less and got away with under 10L per 100km. At other times I had to show my two wheeled friends what Dakdak Trikes can do and paid for it at the next fuel stop. Trikes are made for fun and I don't mind paying a few more dollars on the fuel bowser than I would in the Hyundai Excel, I haven't seen many smiling faces in one of those.
The moral of the story is, what ever you decide to do in the Motor department please talk to people and do your home-work. Deal with people you trust and you will have many years of fun and trouble free riding ahead of you.
The story for Gearboxes is very similar to the motor ones. You get what you pay for.
In the beginning for VW Trikes in Australia, you found all sorts of Gearboxes in Trikes. Some were painted nice and black but had done many hundreds of thousands of kilometres in a Beetle. The Ratios could come from a 1200cc Beetle or a 1600cc which could make your trike do 3800rpm on 100km/h. The motor wouldn't like it at all and the fuel consumption could be really bad. The VW Gearbox is a very strong Gearbox that could handle more than 150Hp no problem, but there is a limit on any mechanical part. If you don't mind being stuck on your big holiday in the middle of nowhere, by all means get one off the wreckers. But at least buy one out of a later Beetle so the ratio is half right. My Trike does 2800RPM at 100km/h, which is just right and I can cruise on 120km/h without putting much strain on the motor.
After a lot of research I found that there are a lot of mechanics who can play with motors, but only very few know enough about gearboxes in VW's. Having problems later can cost you much more than doing things right in the first place.