This page covers models from 1970 thru 1976.  Models covered are R50/5, R60/5, R75/5, R60/6, R75/6, R90/6 and R90S. The /5 series first came out in late 69 to be the 1970 model.  only a 6.3 gallon tank.  It was considered by all of the motorcycle magazines to be very ugly. To provide an alternative, BMW came up with a new design.   BMW came out with a smaller tank of only 4 1/2 gallon capacity.  chrome panels on the sides and has become known as the "Toaster Tank." very unpopular in those days.  Now the magazines and riders both made funAll at once the older "ugly" tank became far more popular. We wondered why the underside of the tank was so different from the largerIt wasn't until mid 73 that we found out why.  It was a space for a, soon to be added, master cylinder to actuate the disc brake of the nextAs far back as 72 BMW knew that a hydraulically operated disc brake The large tank was still available as an option, but very hard to get due to

the reluctance in the acceptance of the "chrome tank" that was the butt of manyButler and Smith, the importer, didn't order nearly enough bikes with the large tank.  They also "couldn't get" but a trickle of large tanks as spare parts, or so they said.  How come I was able to get them by the dozen directly from Germany from various connections through the factory?  The Germans also couldn't understand why anyone would want the small tank.  motorcycle store andover njThey had plenty of largeharley davidson for sale on craigslist mn tanks and were happy to arrange for me to get them through an "underground"chicago bulls motorcycle helmet

source, which I never understood how it happened, but I wasn't going to ask tooThey were very happy to learn that not all Americans were "small tank" crazy.  dealership had dozens of the small tanks sitting in storage. wanted a different tank from stock it was always a larger one, not a smaller one.  most notably Heinrich and Hoske, offered tanks up to about 10 gallons. In mid 73 we noticed that the large tanks had the wide cut out for the masterused bikes for sale in tirupati cylinder too, same as the small tank.  motorcycle shops in woodbridge vaThat reduced the capacity to abouttomtom motorcycle gps usaThe two are totally interchangeable, as is the small one.motorcycle jacket hump back

The tanks in 73 have a very confusing history.  There is no rule for the tank in 73 because there were 4 tanks that came out on new bikes.   Some started coming with the chrome panels and pin stripping. Later they came with no pin stripping.  Then some came with no chrome.  To compound the issue is the fact that we dealers could swap a tank in minutes.  One could change the color set in less than an hour and so our customers could come in and have us build aWhat went out the door for tank and color had little relationship to what BMW assembled.  We tried to have at least a half dozen color sets in stock as spare parts to meet the demand. I was quite shocked to get a call one day from a friend at Butler and Smith. He wanted to know the part number of the rubber knee pads.  I asked why and he informed me that they wanted to order them and had no part number.  also asked why he called and not someone else.  His answer was that they

knew that we were friends and there was a better chance that I would give himThey were right, as he was the only decent person working thereBesides, why stonewall them, BMW surely must know the partMy "inside" person at the factory never got discovered. The Europeans hated the chrome as much as the tiny capacity. Knowing this, BMW had rubber knee pads made to go over the mount for the chromeOne could remove the emblem and carefully slide the chrome off and glue on a rubber pad.  That one small change completely altered the personality of the entire bike. I ordered the knee pads by the dozens and we never had enough to satisfy theWe hardly sold another bike withNearly all of our customers with the chrome came in to get the rubber pads installed, or buy a large tank.  My dealership was the only one in the country with the rubber knee pads.  The other dealers were for losing new sales to our shop.  We offered new bikes with the large tank, or rubber

pads for those that liked the small tank, but not the chrome.  have seen the two large stacks of chrome panels.  I hated them so much that when I sold my shop, I only took two sets with me and left dozens.  more in a long list of errors on my part:-( The front view of the cutout This shows my hand in the enlarged area for the master cylinder.  about 5" wide (125 mm) at this point.  A tank without this area has the tunnel going through the underside at about 1/2 this width.  please send me this measured dimension of the narrow tunnel and I will add it The Bottom view of the master cylinder cutout This shows another view of the cutout for the master cylinder.  bottom center of the picture is the welded center line of the tank.  width would stay the same through where my hand is positioned on the old tank. The newer tank with the cutout for the master cylinder will fit just fine onThe older tanks won't fit on the models with the master

When the /5 model came out in 1970, it had only the large 6.3 gallon tank. The cap hinged from the front and fastened at the rear.  led to some injuries from riders going over the handle bars.  In 1972, BMW came out with the hinge at the rearThat configuration presented less of a danger. That meant that the large tank came in 3 varieties.  gas cap for 70-71.  2.  Rear hinge gas cap from 72 on.  The large vacant area for the later master cylinder.  Very few of these were seen in the USA. Can you imagine going over the handlebars on that bike? You could have a "serious injury" before you even landed.  Isn't that tank just plainPhoto supplied by Stephen in Seattle, thanks. In 1974 with the advent of the /6 models, BMW chromed the gas tank cap. Prior to that it was just aluminum and didn't shine up well.  In 74 the "S" model had a different shape tank.  /7 tank was the "S" design of shape and a different cap.  one to have as it is really beautiful.

The cap has a gasket under it to seal fuel.  A rivet is pressed into the cap to hold the parts in.  It is hard to remove.  flats on the sides so that pliers can get a good hold on it and rotate whileSome owners tap the hole and install a screw.  makes it easy to repair in the future.  I suggest using Locktite on thatIf it falls into the tank, it is hard to remove again. The gas cap is mounted with a hinge pin.  It is 1.380" (35 mm) in length and .155" (4 mm) in diameter.  At one end are teeth that are .003" (.08 mm) larger in diameter than the main shank.  It is these teeth that holds the pin in the cap.  The cap can be removed by gently tapping the pin out. The holes in the two sides of the cap aren't the same size.  One is a loose fit and the other is an interference fit for the teeth of the pin.  better if the pin is tapped out so that the teeth don't go through the cap, butIf the interference hole is too large for a tight fit,