Forum bmwbike.com

I have recently acquired a 1966 Hoske gas tank which was supposedly for a /2.
Upon removal of the many layers of paint, I have found that it is marked as a plunger
frame tank (R51/3). I understand that plunger frame tanks can be made to fit on a /2 frame
with some adjustments to the lower mounting bracket and possibly to the front.
Does anyone know exactly what needs to be done, or if possible, know of anyone
who manufactures "adapter" plates? I realize this is a longshot, but it never hurts to ask.

At a minumum can anyone tell me exactly how plunger tanks differ from /2 tanks?
Or even better, if this tank will fit a /2 without adjustment.

Thanks in advance to anyone who can help me with this piece of BMW obscuranta.

Hi Jeff!

I'm not going into detail as I'm pushed for time, but the plunger tanks and the /2 tanks have a totally different form. In theory, you can exchange them around. The main difference is that the distance between the front tank mounting and the two M8 x 1 mounting holes at the rear/underside of the tank is longer with the plunger models than with the /2 models. As you mentioned, you have to make a distance plate to bridge this difference.

Best regards,

Mark
Mark Huggett GmbH