soviet flamethrower bike br3 because otherwise it has to have a chance at setting itself on fire at br2.
br4 because in sets up in under 30 seconds has to be a medium mortar and can run before you can shoot back.
More soviet guns is only better would make a good premium squad if you already have one of everything.
letting drivers shoot there guns because if you can drive with vodka you can drive with gun.
because if it fits it sits making me wonder in the ussr ever tried to mount a recoilless rifle on a bike.
br3 if it fits in a tank and a jeep the soviets will find a way to mount it in a pike i pity the gunner or the welder. 
feel free to add any new ussr bikes i missed