Thanks very much, Gerd, for the unmolested original photo and the new ones.
If you don't mind, I will tell the tale here of my own saga in trying to solve this very interesting puzzle.
I know absolutely nothing about motorcycles so I had to use another method to try to resolve what the answer might be.
As I have before, I decided to use the owner's name as my starting point and try to work my way around to figuring out what marque the motorcycle was.
Almost immediately, I ran into an EU law, "The Right To Be Forgotten", which basically allows a person or a company to petition their local country "Data Protection Agency" to not allow their names to be openly presented on such web sites as Google, Wikipedia etc. etc. Many bad things happened to people and companies in Europe between WW1 and the end of WW2 and even longer and a lot of those things they would rather not have available to the general public.
So, when I first started with "Max Bogopolsky", I was getting nowhere.
As I recognized the item on the back of the cycle as a travel trunk, in US English, I Googled that on Google.de and came up with an advertisement for such a trunk which is posted below. That advertisement also gave me the address of the business, Kaufingerstrasse 34, Munich and also confirmed the owner's name.
Here, it got interesting. The "Right To Be Forgotten" law covers direct references to a person or a business in the sense of a written dialogue but apparently not individual photos, especially something like an advertisement that happens to mention a company name.
It apparently also does not cover the mention of individual names or company names when contained in lists of names or transactions that do not have to do specifically with that individual or company.
I then Googled Max Bogopolsky, Kaufingerstrasse 34 Munich and viola...........
I got a reference to the State Archives of Munich Police Headquarters where there was a listing of hundreds of names of people who came to the attention of the Police, in this case, 1933.
There was Max Bogopolsky in the list along with the following information.
Jewish
Born 3/6/1890 in Kherson, Ukraine
Leather Goods Business Owner
Married to Rosa
Referred for investigation for the following.
Fraud
Perjury
Unfair competition
Selling out without reporting it
Pandering
Racial Defilement
Filing Accident Report
Put in Protective Custody
Expelled
I have seen this before, he was caught up in the National Socialist First Phase to rid Germany of it's Jewish population wherein they harassed Jewish people until they left or were expelled, early in their administration.
I then checked several Holocaust sites and found our name again on a long list of people who had apparently left Germany with outstanding debts. No other data.
I then tried Googling the name on the national Google sites of known destinations for Jewish people who were able to leave Germany early on.
On Google Palestine, I found in The Palestine Gazette 06/06/1935 in a long listing of business transactions that Max and Rosa started a business in Jerusalem on 29/08/1934 and that on 01/05/1935, that company was dissolved and Max took over as sole owner. No further details.
On Google Israel, I found a telephone listing for our Max and it listed his occupation as "Broker".
This was in the 1950s I think, I forgot to save the page.
Finally, I went back to the photo and Googled Munich Koffer Bogopolsky and found an apparent out of date advertisement on Alando.de for a photo which seems to match yours. I will try to paste it below. I could not find the photo but it did give the name of the motor bike company but by that time the puzzle was solved.
In any case, it was quite an interesting research project and shows again that there are many ways to come to some sort of answer than just looking for photographs.
Bill
4 Ergebnisse für pkw anhaenger motorrad
www.alando.de/sch/i.html?LH...1... - Translate this page
Tandemanhänger Auto Pkw Anhänger koffer offener Kasten Transporter ... Großes Foto Conrad Weiss Motorrad mit Reklame Anhänger Bogopolsky Mädler Koffer ... Conrad Weiss Motorrad mit Reklame Anhänger Käse Hindelang München !