Re: Predator 670cc V Twin bike
You can build up a powerful 212cc hf motor that will take you to 80 for a little more than the twin. Problem is that at higher speeds you get other problems, the bouncing rear end for one. But whatever. Build it! You won't find any forum well suited to a project like this and you probably will never meet another person with a custom like this out on the road. Your best bet I think is the DIY section here and others, you kinda have to look for the customs.
I don't always listen to Alice in Chains..... but when I do, SO DO THE NEIGHBORS