S90 Update 9 – The Seat

Ok so the seat I bought last July turned out to be pretty bad. Some people say I could still use it possibly by painting over it with clear or something but I don’t want to. It’s a goner afaic. And so I went ahead and looked for a pre used Honda metal TMX seat. Believe it or not despite the TMX being incredibly popular it’s still very hard to find a metal one as most seats now are plastic. I chose metal so I can bore and weld it. I managed to find one after weeks of searching for P500 from a cafe racer modder on facebook who had it lying around his garage.

Here they are:

According to http://s90partspuzzler.blogspot.com, the go – to website for all things S90, my frame # ‘s90 827556’ falls under the ‘late model’ category. The part number for my frame would be ‘50100-028-100Z’ for chassis numbers 722,787 onward. These chassis are supposed to have a seat adapter that looks like this:

My seat however looks like it was hammered down and looks like this:

pre painted
after painting

A nut had been welded on I suppose to accommodate the bolt for the gas tank and a replacement seat.

The donor chassis number however is ‘s90 634920a’, which makes it fall under ‘Variation 2: “Middle”, with part number 50100-028-365Z: frame number (chassis # 570,699 to 646,983). The seat adapter for this frame should look like this:

The donor frame looks like this:

Unpainted. Still in fantastic shape afaic.

The rusted out seat adapter looks like this:

And the rear looks like this with two 10mm holes for bolts:

The Honda TMX metal seat adapter looks like this with two ‘tongues’ sticking out:

and the rear area has two ‘wings’ for bolts.

Here’s a direct comparison front and back:

The TMX seat is also about half an inch on either side wider but that’s no big deal. So anyway, here’s what happens when I try to connect the new TMX seat to the frame:


Here’s a mock up with the tank and seat. It may not be to spec as I’m trying so hard not to scratch the frame.

So in my uneducated guess, I think it can be done. I just have to:

  • Raise those ‘tongues’ on the frame to snugly accommodate the ‘tongues’ on the seat.
  • Have a welder weld bolts on the seat so it will go through the wings on the frame.
  • Buy seat rubber mounts and customize as needed to make sure my ass is well insulated from riding this thing around.

Once fitted snugly I can have it repainted to protect the welds then have it reupholstered. Once again the goal is to make it look like this beauty, although I’ll be happy with just getting close:

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