Correct gas cap

[JakeF]

In most photos of an R90S I see a gas cap that is raised and chromed. Mine (a very late serial number 1976) is neither. The patina on mine looks to be the same as the gas tank so it appears to be original but I don't know since the bike came with no history. I like the look of this cap and don't plan on changing it but wanted to see what forum users knew about it.

[schrader7032]

I thought this was the proper gas cap for the larger tank, in anticipation of the /7 models. IIRC the late /6 and /7 tanks are the same.

[JakeF]

The serial number of my bike puts it in the last 200 produced. I wonder if that had anything to do with it?

[schrader7032]

Do you have a picture of the tank?

[khittner]

I don't know when/which frame numbers the switch was made to the flush-cap, /7 fuel tanks, but it's my understanding that, at some later point in the '76 model year production run, the fuel tanks were changed from the earlier, chromed, "flip-top" caps, to the screw-in flush-top style. My DO '76 R90S also had the flush-cap tank (and while I didn't have the full history of the bike when I bought it used, I had no reason to believe that the gas tank had ever been damaged and replaced with the later, /7-style tank), while my '75 R90S had the flip-top tank. Your screw-in gas cap looks to be the correct smooth semi-gloss/satin black finish; later and current replacements for that style of cap have a textured, flat black finish.

[ksiemon]

If you didn't know there are two books out there every Airhead owner should have. Both buy Ian Falloon. These will help with 99% of any questions you may have. Fuel caps, paint marks in bodywork, chrome hardware, mirrors. Ian is perplexed / confused about the faring holes......They were put there so you could pop out the headlight shell with the screw driver! The older airheads just had a fixed spring in the lower ring as you all know. Later ones had a screw at the front so the owner could loosen it, then it would almost just fall out. I had a "S" I purchased in July 75 and it had the holes. I got wrecked. My second one (still have it) was built in June 75 had no holes but the old ring. It's a pain in the ass to pop out.
Anyway these books are all over the internet..........

[skychs]

If you didn't know there are two books out there every Airhead owner should have. Both buy Ian Falloon. These will help with 99% of any questions you may have. Fuel caps, paint marks in bodywork, chrome hardware, mirrors. Ian is perplexed / confused about the faring holes......They were put there so you could pop out the headlight shell with the screw driver! The older airheads just had a fixed spring in the lower ring as you all know. Later ones had a screw at the front so the owner could loosen it, then it would almost just fall out. I had a "S" I purchased in July 75 and it had the holes. I got wrecked. My second one (still have it) was built in June 75 had no holes but the old ring. It's a pain in the ass to pop out.
Anyway these books are all over the internet..........

If I could get just one which one would you recommend? Just curious.

[ksiemon]

For you guys that are working on and have a 90S..... just get the BMW R90S one. It has everything you need and great pictures + all the info !

[kirkpatrick3890]

I really love the R90S model and helped Ian Falloon with pictures of my R90Ss and information for his book, "BMW R90S". I was also very fortunate to be pictured riding my R90S on the front cover of that book. That picture came about because I loaned an R90S to BMW of NA at the introduction of the R1100S, so they took pictures of both bikes riding side by side, as well as other pictures, one of which is the cover picture. They used the pictures for the press introduction of the new "orangw-ish" R1100S.