As least, those who barely sleep around only have 50% chance of divorce. Christians and all , it's still about 50%.
Can I suggest the thinking on what cheap cost large engine to buy for anyone's speedster change slightly. I suggest, based on 90,000 miles of use and many of these built and abused and still running, instead of the low cost 1915cc, go with the 1904cc. Could read 1903cc, but all in how you build the engine, that one cc does not matter. It uses the 74mm stroked crank and you get more low end torque with any crankshaft with a longer stroke. And, on the bore, uses the super long lasting and lighter weight 90.5mm, and there are many good brands available. The rods can remain stock length, as you are only adding 5mm to the stroke.
So, compare the 1915cc to any well built 1904cc and you will find you have more torque, more horsepower and a much longer lasting engine with the 1904mm. It's not that I am against using 94mm pistons, but one really needs to spend a ton of money to get quality parts and as the larger piston has more ring surface, there will be more chance of blow-bye, past the rings. More friction and more surfaces to keep cool.
There used to be the popular cheap 1835mm which had the stock crankshaft and 92mm bore kit. They were terrible in lasting very long, over heated and were cheap, so everyone bought them. More forward to about year 2000 and the hot ticket is the low cost 1915cc, as they are cheap to build.
Even if you do have to spend a few more dollars on the 1904cc, due to the 74mm crankshaft, often no clearance problem occur in the stock case or anyone can use a small rotary device and remove the very little case material . It does not require major surgery to the case. I would also suggest the strong and dependable 1776cc, but put in a nice cam and spend money on the heads and dual carbs and you again will have a longer lasting engine with more horsepower than the 1915cc.
I will not build the 1915cc. I have build engines using quality 94mm's but they are expensive to get those right. The better combinations use a larger stroke and the 90.5mm for a longer lasting engine. I think one speedster owner posted a picture of how much the heads need to be cut to put in the 94mm cylinders. Now, just common sense would tell all that is border line on machine work.
People make up for leaking 94mm cylinders to heads, using copper gaskets in the heads, but copper gaskets crush and are only suggested by the professional engine builders in turbo only engines. Most turbo engines see very little street use or running time. Unless you plan to re-torque your VW engine heads, which someone put in those copper head gaskets, you will certainly find in a rather few miles, the heads will be leaking past those copper head gaskets.
I am trying to save everyone money by using what I know are longer lasting combinations on engine sizes. If you shop by price only, buy the 1915cc and good luck ! I drive my air cooled engine vehicle about 10,000 miles/ year, so I want it to last, in all kinds of weather and temperatures.
Your engine builder may be careful in building your 1915cc engine, but by design, you will not have the best combination.
Other than the 1904cc, I suggested, if you have the money go for any engine using 90.5mm cylinders and something with over two liter in displacement. It should run great ! Plenty of torque and plenty of horsepower. ---George K. ---