Forgive me guys here but I don’t see what the problem is. The seat pan on a 550k0 is the same as the 500k, so that means 2 captive nuts welded to the hinge side for the bolts to screw into and 2 studs welded to the pan for the lock plunger to bolt onto. If you strip a captive nut (as I have done) you just grind off the old nut and weld on a new one, if you shear one of the lock plunger bolts off you trim it off and weld a new one on. It’s far easier to just use a standard 6mm bolt with the head still attached, just drill out the old bolt, fit the new one through and weld the head of the bolt to the pan. More secure, more metal to weld to and if you really want you can use a stainless bolt so it rusts far less. As the foam retains water over time, rust is a major concern, most pans rust through from the back than from the front.
Just something I noticed when test fitting my newly powder coated seat pan to my 500k frame was how poor the fit is, with the lock plunger and hinge bar fitted the rear of the seat doesn’t actually touch the frame at the back, this means that any weight, like a pillion for example, distorts the pan and causes it to crack halfway down, something I’ve spotted on numerous 500 seats over the years.
It’s far easier to spot this Poor fitting with a bare frame and a bare pan. The back of the pan needs a small rubber pad attached to the existing rubber pad at the rear to eliminate this problem, something around 4mm thick I estimate.
