Originally Posted by Davezilla
Hi, welcome to the forum... try reading in the high performance section in here and you can decide whether to pay somebody big bucks for a fast engine or read up on porting, intakes, exhausts, and ways to boost compression and do your own mods.... 50mph from these engines is not impossible but you're asking a lot.
you also need a bike properly prepped to handle these speeds so there's a lot more than just putting an engine in and being able to go 50mph...
Exactly, getting an engine to those speeds isn't the hardest part, it's doing so more safely and being able to stop that are going to take twice as long as an engine build would. My bike has hit more than forty five quite a few times, but I've never stayed at that speed for more than a couple minutes max because I like my limbs.
Anyways that's with a China girl that's got a good bit of modifications, but isn't a full on race bike. Go with a different engine for reliability like a morini. You'll also need a solid bike with some disc brakes and all that is just the beginning...