I’m putting together a RZ350 for a local vintage racing series. Just started into it again after Christmas so I machined down a FZ600 arm over the weekend and will pick the frame up from Powder today after doing a lot of bracing.
They changed the rules and I’m now allowed to run 17” rims which is great as there is a much better selection of tires.
I was thinking about fitting a 110/140 back and front, but I spoke to the track side tire guy at the bike show at the weekend and he said think about fitting a 4.5 inch in the rear as he has a much better selection in 160’s from Dunlop, Michelin and Pirelli.
I’m still leaning towards the 140 but was wondering if there was a 4.5” rim that was an easy swap for the FZ arm. Bear in mind I’m in Canada so the choice locally will be fairly limited but could grab something from the UK on eBay
I'm going to run an FZR600 front end so it will have a 17x3 rim that should be fine for a 110/70.
I think there is some good advice above and good reasons to stick with the 140.
GS500 and 400 Bandit wheels are plentyfull and cheap and it looks like they both have a 17mm axle. From what I can find the GS500 swing-arm is ~216mm at the axle ( I'll need to confirm) and I just measured the FZ and its ~220mm so it should be a relatively easy install, and the caliper mounts above the wheel the same as the FZ.
The Bandit sprocket carrier looks a lot wider though, maybe a GS500 carrier would fit. The caliper also mounts underneath but it would be easy to put a bracket for a torque arm on the underside of the swing arm.
The 4" rim is probably a little better for the 140, but a 3.5 is also specified as an alternative. It seems like Pirelli would be the best tire choice in this case as they make 140's in Slicks, Wets, Rains and Supercorsa's and seems to be the race tires most commonly used 250 and 300 ninja's with the 3.5" rear.