Like the title says I joined but disappeared .Things happened and I put off working on my '88 K100.I bought all the parts needed to fix the old gas problems that the bike came with ,cleaned out the tank and stopped. That was back in 2015 .Well,last week I got to it again and took it all apart.I gave her new fuel lines ,new FI rated hose and clamps,a new pressure regulator,,new o rings on the injectors,and now I'm putting in the new fuel pump ,filter,and sender into the tank.I was wondering is there an o ring seal I can get at the auto parts for under the sending housing at the bottom of the tank ,you know,what kind of material does it need to be made from? Anyway,I'm Ed (yamaguzzi ) and I'm finally back into this bike in the final push to get her back in service.She has 12000 miles on the clock and hasn't run since 2004. She was a gift from a good friend and I'm really looking forward to bringing her back from the dead .The overall condition of this machine is near mint so it's a very worthwhile project.

Welcome back.   Why not just bend over and let the dealer fix you up for the correct metric o-ring?  If you move quick you can get it for $8 before BMW cranks the price again.

If you decide to go local, I would go to an industrial bearing and seal supplier and get the correct metric size o-ring.  Trying to get something out of the generic o-ring box at the auto parts shop will get you close, but probably not close enough to not leak.  If you really want to go auto parts ask for viton material.

I 'll probably end up going to the dealer if I can find one close by.There used to be one right in town but he closed.I saw in another post that it is 55mm x 45mm x 5mm and that is what I went looking for with no luck.I put the injectors back together today and now it's time to get into the tank so I'm dead in the water until I get the O ring but I'm having fun working on this bike.It is very different from the vintage stuff I usually fool with so it's a learning experience and at 68 years old that keeps my brain sharp so it's good.

A lot of people get their parts from this outfit.

http://www.maxbmwmotorcycles.com/fiche/DiagramsMain.aspx?vid=51752&rnd=12082016

Thanks , It's good to know where to look. I mostly fool with old Moto Guzzi and Yamaha 2 strokes so finding stuff for the K is a new search for me.When I finish this K100 I'm going to start to focus on the sweet little R60/5 I have .

I managed to get one at a bearing and seal specialist. Bought a Viton one and a spare just to make sure I will never need it.
I did go to the local auto store but they just looked at me as if I had asked for a spaceship painted in snake skin pattern.

RicK G wrote:l auto store but they just looked at me as if I had asked for a spaceship painted in snake skin pattern.

I thought you did?