Technical Information Pages for the restoration of Zündapp KS 750 and BMW R75


Editor:   ERSATZTEIL- DIENST   Hans-Peter HOMMES       D-41748   VIERSEN   Tiefenstraße 10       Tel. 02162 - 8100933

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Off road - technical problems

H-P Hommes


© 2012 h-p hommes





All participating heavy military bikes on the trip.








 In April 2012 we made a several days off road trip in the Flinders Ranges.

Being not an Australian you do not need to know this place.


The Flinders Ranges are a nature park in the dusty outback about approx. 600 km north of Adeleide.




Our host-  a sheep farmer - provided his simple but pleasantly equipped shearers quarters for our stay.

His farm has more than 450 square km and he still has approx. 4000 sheep.
In former times he owned far more sheep but the severe drought forced him to reduce his stock considerably.

When he speaks of the severe drought he speaks about a period of 18 years. Then in 2009 a huge rain drowned the country.

Then after that until today – 2012 - there was no real rain again.


The landscape is barren, mountainous, traversed by wide waterless river valleys and very dusty.


As there is not such a large amount of Zündapp KS 750 and BMW R75 in Australia all other military bikes were welcome as well.
Getting there took some of the participants several days and some travelled more than 2000 km.


Because we deal with technical problems on this website we would like to have a closer look at the encountered problems during the trip and analyze them in detail.


BMW R12:


Dave with his BMW R12


Because the slopes we drove gave our bikes a permanent good shaking our R12 driver Dave lost a lot of his bike while driving. The last day his front axle turned itself so far out that the wheel jumped out of the brake drum. A better tightening of the screws and some Locetide would have prevented some of the forced breaks.






Kent changes his magneto



According to tradition Kent with his BMW R75 began the round of small repairs and replacements.
His vey old Noris magneto did not work properly at high temperatures. I found out that there was hardly any magnetism and that he should urgently magnetize his Noris again.
To be on the safe side Kent had brought a second Noris magneto so that the exchange was quickly done.
The last day the ignition broke abruptly off again after a bumpy and rocky river crossing. He had not properly fixed the magneto and it had loosened itself, pushed itself up and got displaced by several teeth.
After we had finally found the mistake it was easy to get his BMW R75 going and he happily made his way back to our camp.



Hans-Peter with Ian‘s BMW R75 and Adam in the sidecar


Ich drove a BMW R75 from my friend Ian. When I took it over I already recognized that changing gears from high range to low range was not possible. It felt as if the inner lever jumped out of the switch. But this was not tragic because I could drive very well in high range all the days.

But the last day I ended up at fairly high speed on some very bumpy gravel track which transferred a few very heavy hits on the gear.
The high range jumped out and could not be engaged again.
This happened only during the last 50 km of our trip. The R75 was loaded on our service vehicle and was driven back to our camp. And I was sitting in the sidecar of Manfred’s KS 750.



Ian with his BMW R75



The third R75 from Ian had the same problem as Kent’s R75. The old magneto did not deliver any spark at high temperatures due to missing magnetism. We also exchanged his magneto the first day against a completely overhauled one. After that things went well for Ian and its R75 as it should be.



Zündapp KS 750


There were three KS 750 participating on this trip.


Manfred with his Zündapp KS 750 


Manfred had restored his bike here in Australia. He had changed it to slide bearing shells and put in our new deaxial pistons.

He had renewed everything without compromise.
The bike ran the entire trip without any problems and he was proud not even to tighten a screw.




Kerry und Paul with their Zündapp KS 750


Paul had bought his bike in Germany six month ago. Engine, transmission and differential were completely overhauled in our workshop in Kamphausen.

It was his first major trip with the bike and he had little experience.
Already the first day I had to drive back to him because Paul’s bike could supposedly not be started.
When I arrived some of the helpful specialists had already removed the cap from the magneto to check the contact distance.

They told me that there is a spark but the engine would nevertheless not start.

I turned the throttle grip and with the first powerful kick the engine was running again.

I explained Paul that he had to kick more powerful because I had seen before how timidly he used the kick start lever.


Then I check the new spark plugs Paul had mounted.

The distance was 0.6 mm.
I reduced it to 0.4 mm and from then on Paul could start his engine with one powerful kick all the time.




Peter withn his Zündapp KS 750



Peter Kunze had rebuilt his KS 750 engine with a pressed crank shaft and tatra pistons. 
His bike ran very well. However, he lacked power climbing a mountain and what bothered a lot more he always had blue exhaust smoke behind him. 
He needed more than 1 liter oil for 200 km as he stated. 

It frustrated him to see that the two other KS 750s with their slide bearing shells and the modern deaxial pistons ran smoothly and when controlling the oil level only showed a small consumption and their oil was clean whereas the oil of his KS 750 had a black colour.  


Sure I was pleased to see that my two KS engines clearly showed to be superior in this comparison.





There were also some other heavy military bikes.

They were camouflaged as R71 and produced in a country far east where the workers eat their lunch with chopsticks.
When they ran they did quite well. But often in the evening their owners worked for hours to get them going the next day.
Often they broke down and gave us another break during our dusty drive in the outback.



Russel with a heavy military bike type „special version Far East“


 This camouflaged bike R71 has to be mentioned as positive.
Unique on this bike is the sidecar on the left hand side for driving in Australia and an electric starter.
The starter had been well modified so that no problems occurred during the whole trip.



Martin‘s Pseudo R71


Martin drove Peter Kunze’s solo bikes BSA and the camouflaged R71.
Both bikes ran very well except that they lost a muffler once in a while being off road.



All in all it was a great trip with good friends in a dusty but very interesting landscape in Australia’s outback.






We offer:

Spare parts + Accessories + Repair for Engines, Transmissions, etc. of
Zündapp KS 750 and 600

We offer:

Spare parts + Accessories + Repair
of BMW R75 and Zündapp



H-P Hommes Ersatzteil-Dienst
Ersatzteile + Instandsetzungen
repairing + restoring

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