So what did you have to do to fit the 160 on the rear? And I have no intention of building a race bike I just want to build something that performes better than before and looks the way I want so what did you do specifically to your swingarm?Some things to consider when building a racer or cafe race from these tube frame big motor bikes. We have built several for vintage racing and are now in the process of putting together a pair of Suzuki GS1100E's These are going to look close to the Yosh motorbikes ridden by Graeme Crosby.
First off the frames do flex especially with the modern rubber we can use now days. You can brace the chassis but you can't get all the flex out. One thing we found is that very wide rubber is not the best way to go (we're working with 160 rears) because you overload the chassis and the frame winds up and then springs back . Feels creepy ! So what we have been trying is to use the lightest wheels (because of rules no CF) we can find. We brace the swingarms, We also are using the best 41 mm forks we could find (USD forks are NFG by rule) with fork braces and Ohlins cartridges. By the way Ohlins cartridges in the Showa forks work great (we ran them at the Isle of Man Manx GP) without any problems and they're going to cost you $1200.00 less.
We use Ohlins dual shocks because that's what Yosh used back in the day. They are not perfect and don't work quite as well as the modern single shock but then again these aren't modern motorbikes are they ? You can make the dual shocks work they take a wee bit more fussing with and you need to take care to keep records of your changes if for no other reason than it keeps you keeping your changes clear side to side.
Also remember you will never be able to lean these puppies over like you can a modern sport bike cause shit will jit the ground. We had an old Muzzy SBK here and there were all kinds of work done to the cases to allow for more clearance while leaned way over. I don't know if it was Muzzy's guys or someone else but it looked good and did allow more angle. Also looked to be a ton of effort put in to it.
So my advice. Get the weight down, stiffen the swing anr and chassis, find modern wheels, and spend your money on good fork innards,and shocks...............Then ride the hell outa the thing.