Boxerworks.com

All,

One of the most important changes I wanted to make on my new to me 83 R100RT was to remove the Corbin aftermarket seat and replace it with an OEM seat I found on Ebay - The seat I purchased on Ebay is a nice original seat with the hinges, rubber grommets and "pin" piece that snaps into the lock all present from factory.

I unscrewed the Corbin from the R100RT seat frame and attached my OEM replacement.

When I got the assembly back on the bike, after struggling to get the hinges over the frame rail and in position, i got it in a good position and it will now close properly/level but the pin (that snaps into the lock mechanism) WILL NOT ENGAGE and lock - It seems the pin needs to be a bit longer - I noticed the pin on the Corbin seat that I removed has a washer/shim to make it a bit longer to engage lock.

Does the original pin have any adjustment?? Can it be turned to lengthened??

Pull that tapered rubber thing off of the spike and take a look. Probably a jam nut you can loosen and extend the spike some. Make sure the notchis pointing in the correct direction after turning the spike .

much appreciated!

Pull the conical rubber of the latch post, as George said and see if it closes.
Careful trying to turn the latch post, it will most likely be rusted to the nut (under the seat foam) and could break away from the seat pan.
The latch itself may also be worn, preventing engagement of the latch post.

the receiver latch is in good working order and worked fine with previous seat i removed. i removed the rubber washer off the pin and there is no adjusting nut and looks as if there is no way to adjust the pin - pin looks welded to the seat bottom - photo attached

Congratulations on finding a very nice colour matched seat for your new R100RT on eBay!

Have you had a close look at the rubber bunges slotted into the metal seat base, they are supposed to rest on the subframe loop and carry the weight on the seat. Maybe they are too tall for your new seat to fit properly, and allowing the loch pin to engage.
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This could well be another point worth mentioning in SteveD's "Airhead: quirky is as quirky does" thread; the rubber bunges under the seat rarely do the job they were intended to do, so the seat hinges end up carriying too much weight - which results in cracks aroung the hinge bases. Their detachment is often very much helped by ferrous corrosion of the metal seat base in areas where the climate is cooperative

good point regarding the small round rubber stops - i'll be home next week and will investigate - much thanks for the input!

That seat looks like it's been cleaned up and painted at some stage. The paint is usually a flat to satin black that flakes off and shows light surface rust underneath. It's commonly seen. The bolt is attached on the other side of the base by a weld, so no adjustment. Sometimes that bolt can lose its alignment just a bit.