On the other hand, if you move it more to the vertical, the shorter the wheelbase can be. This example also being a Guzzi. This one at Le Container.
Or you can add another cylinder and turn everything sideways. This one from Rocket Garage.
What prompted this, you ask? I've got a reprint from way back when I got from Lindsay on how to make your own motorcycle that I was thumbing through. It shows you how to build a single cylinder bike from scratch, including the carburetor. Nothing fancy here but it's within the realm of reality for someone with both welding and machining ability, along with plenty of time on their hands. Other than the time on my hands part of it, I'd say I fall into the category of those capable of building said motorcycle. And if you have the ability and machinery to build said motorcycle, would you want to settle for simple design that's nearly 100 years old? Why not something a little more current?
How about something like a Linto? Basically a pair of 250 Aermacchi motors hooked together to make a 500. Like TV Tommy Ivo, Russ Collins and many others, If you want to go faster couple up another powerplant. If two's good, three's even better. This photo's from here. Lot's of cool stuff at the site but it's in Italian.
Obviously if you were going to build something, you couldn't hope to out do any of the modern manufacturers. The only guy I can think of who managed that was John Britten. However, in the earlier days of both car and bike racing, there were a lot of specials built by "average" guys.
Guys like Smokey Yunick for example. Photo from here. However, there aren't too many racing venues for guys who want to start from scratch and build themselves a world beater. Even Porsche didn't have much luck cracking the Indy nut when they showed up. Land speed records are still probably the most available to a homebuilder who wants to try his hand against the best or play beat the clock. That and drag racing. Drag racing is still open to experimental designs. They've always been a run-what-you-brung haven. I had a lot of fun and some success with both my drag racer and my vintage road racer. I'm no Smokey Yunick, but I did have a bike on the front row at Daytona, so I've got that going for me. Plus I had the pleasure to meet Smokey one time. There was a guy you could learn things from.
Now-days a guy could build himself one of these. It's a HAMB dragster. Go as fast as your wallet will allow. Compete against other guys racing on the cheap within a short list of rules. Get me a 235 Blue Flame Six and a pile of tubing and I'd have a dragster in no time, he says to himself with a wry smile.
See how my mind works? I've got a million and one projects to finish, about a half-million more I need to start on when I get those done, and I'm still thinking of something else to play with down the line. It's a friggin' curse. Someday, however, I'll come up with the masterpiece/capstone project for my career. And you'll be able to buy it cheap because it'll be in a half finished state when I go belly up like a bunch of other projects the Missus will be cursing me over.
Enough already. Warm again today. Off to do a little hand to hand combat with the 900.