I found an unloved 1985 K100RS last August and have been steadily putting the old girl right. I've learned a good bit from this and other on-line sources. Still, there's much yet to know, I'm sure. I've seen references to fuel strainers in the tank. Some are offered on E-bay as well. I renewed the in-tank filter as soon as I got the bike (NAPA, thank you very much!) but I never saw a fuel strainer while I was mucking about inside the tank. Was this actually fitted to 1985 K100RS (US) bikes? TIA

Yep they all have them. It's attached to the bottom of the fuel pump and is virtualy invisible from the peephole. It's a plastis of some sort with a very fine mesh, is about the same diameter as the pump. You may have an aftermarket pump then it may have a long thin one which goes onto a spigot on the bottom of the pump and also is almosy invisible. You need to remove the pump to get to it.

Basically: The pump sits in fuel and pumps up fuel directly, sending it through the fuel filter, then out to the injectors. The strainer stops the pump gunging up, the filter makes sure the injectors are safe. It's a good idea to keep both in.

the part no is 16121455126 and the thing is really cheap - do not buy it used as it does not make any sense. the thing gets stuck with really tiny little bits just like your water kettle in the kitchen. buy new, buy original hahaha

good luck with your bike mate!