I will admit, their welders aren't as good as they once were. As far as rust, quit slouching and get 'em on the bike and give the them some two stroke protection.
Full specs on new motor? What jets in the carbs? Did it pass a leak down after assembly? Did you do a leak down before pulling it apart?
It's gonna be a lack of fuel issue or an air leak.
There has always been PV options. But here is why you don't see many. Most guys dumping the big bucks in to these ol machines are drag/dune racers. No PV needed. Those that really benefit from them are trail guys. Majority of the trail guys aren't building high dollar stuff. It's basically a dollar to fun ratio. If the banshee was touted and designed as a Moto X machine, I'd bet it would be a totally different story. But it was a machine aimed at being king of the dunes. No need for PV's on a machine meant to sing all day at over 9K rpm.
Meh, that's a little lofty. By today's standard, they are dated. But when they came out and options were still limited they held their own. The set I sold to whitbread I was able to get to Rev when I put bigger stingers on them.
Tons of 250R stuff with PV's sorted out. Certainly makes for a more controllable ride. Just about useless for drag racing unless the machine is a heavy bitch. Plenty of drag snowmobiles still run PV's surprisingly.
You'll want them to be 14 1/2" to 14 3/4". And make sure they are valved a little heavier to compensate for the banshee's weight. If you can't answer those questions, I'd look for used stuff actually set up for a banshee.
Not a bad set up. There was a fella on a trail ride a few years back that had a set of RZ jugs ported by Spec 2. He used a zeeltronic ignition and it was pretty fun. Not a power house by any means. But a broad 65-70 hp machine in the woods makes for an sweet ride.
Only a handful of guys with aftermarket ignitions use them to their potential. If you legitimately drag race and especially on big open stretches, it is nice. Pretty much anything else might as well just have the timing plate.
Suspension and porting/domes.