Can anyone tell me what sachs engine this is? the exhaust bolts are not straight across. numbers on the cylinder are 123.131 and on the case 923/1D Thanks in advance

5.2 or 5.8
The Mahle cylinder is the 5.2, the Kolbenschmidt is thd 5.8..I think....
They run almost the same...

Stroke is the same, the 5.2 bore is 2.047, the 5.8 is 2.165..
Model 133 and 143...
The last version of the 5.8 had a roller rear bearing, a ball fits the same space..

Am going to say a 4.2 model 309 saw engine. Has only two carb spacer bolt holes and the exhaust port looks small even though it has the telltale staggered bolt pattern. Reminds me of the Stihl 090/070 engine.