Hi all - I really need help on this.

My 1961 O&K minidumper has a 1-cylinder air-cooled diesel engine that may be a Hatz. It is stamped 1964. I am looking for ways to adjust/repair it as it is smoking badly and does not have much power. (It also starts badly but that may be due to bad cabling to the glow plug (which works))

This engine is also in some Fendt tractors and in at least one Porsche tractor of the period.

It has the following text on a plate on the sump:

O&K Typ 113 R 1 D
BJ 1964 (this is Baujahr or year of manufacture)
18PS (18 HP)
Hub 135mm
Bohrung 110mm
Hubraum 1238 cm3

Does any of this ring a bell or do you know anybody who might have information on an engine like this? I really need to make it work soon. It is taken half apart now but must be ready for construction work soon...

I am looking for exploded drawings, a manual, tips on how and where to set the timing etc etc.

Thanks in advance.