MZ ES 150 built in 1967 with single seats, restored
|Manufacturer||VEB motorcycle factory Zschopau (MZ)|
|Sales description||IS 125/150|
|Production period||1962 to 1978|
|great||Motorcycle (ES 150), light motorcycle (ES 125)|
|Single cylinder - two-stroke - gasoline engine|
|drive||Chain, fully encapsulated|
|Brakes||Drum vo / hi; 150 mm|
|Dimensions (L × W × H, mm):||1990 × 750 × 1150|
|Empty weight (kg)||112|
|Previous model||MZ 125|
|successor||MZ ETS 125/150|
The motorcycles of the ES 125/150 series rolled off the assembly line at VEB Motorradwerke Zschopau between 1962 and 1978. They supplemented the ES series manufactured since 1956 and replaced the RT 125/3 . The ES 125/150 is one of the most popular motorcycles in the world, although no reliable information is known about the total number of units. In 1964 the machines were awarded the Q quality mark . 
The frame of the ES 125/150 was new both in terms of design and production. Instead of a welded or soldered tubular frame, it had a pressed steel frame . The two frame halves were connected exclusively by flanging over a fold without welding points. This enabled the torsional stiffness to be increased by 20%. In addition, there was no need to import an expensive multi-spot welding device.  This frame structure has been with minor modifications in the series TS 125 used by the year 1985th A comfortable full swing construction was used for the chassis, analogous to the large series. Like the rear saddle carrier, the front wheel carrier was cast from light metal. In respect of a steel part reduced mass about the steering axis impacted as well as the relatively large 18 "wheels to a considerable extent on the driving stability. Nevertheless, a certain tendency was to link commuting, which could for example emerge as a result of not completely round running wheels or incorrect balancing. [ 3] The full-hub drum brakes were basically adopted unchanged from the predecessor series, and the now internal operating levers from off-road sports contributed to the closed appearance of the machines.
The engines were developed from the standard engine already used in the MZ 125/3 and the SR59 scooter . The crankshaft was redesigned; the crankshaft bearings were no longer lubricated by the mixture, but by the transmission oil. The connecting rod was converted to needle bearing.  The mixing ratio of oil and fuel could be reduced to 1:33. There were also cylinders made of composite cast. The cast iron - linerwas encased with a cylinder body made of aluminum. Characteristic for the engine was a favorable torque curve over a wide speed range, the well-muffled exhaust noise and full throttle resistance typical for MZ, but also the tendency to glow ignition after the engine was switched off.  From 1964 onwards, a special feature of the carburettor was the possibility that turning the throttle grip beyond the zero position would lead to a complete interruption of the spray supply. In this way, irregular ignitions when driving downhill or even glow ignitions could be suppressed. The two variants 125 and 150 differed from one another only in terms of pistons, piston pins, cylinders, cylinder heads, carburettors, intake manifolds and secondary ratios. In a test report from 1963, both types reached the official top speed with the driver sitting upright and came up to 100 and 103 km / h with the driver lying down. 
A special feature is the fixed-frame headlight. The headlight housing formed an extension of the bench-tank line , similar to the DKW Hummel 115 . The series owes its nickname "racing flashlight" to this design. The exterior of the small ES series was praised by the trade press as a harmonious combination of function-related and designed form, as was the very good seating position and location of all controls.  For the first time, there was a headlight with asymmetrical low beam on a production motorcycle. In contemporary reports, the spotlight was therefore rated as very exemplary , but the unchanged 6 V system with 45/40 W headlight power limited the possibilities. The ignition system was an interrupter ignition with a 6-volt battery under the left side cover and an ignition lock with 5 positions from left to right: ON with light on, ON with parking light on, ON without lighting, OFF, OFF with Parking light and pushing.
The machines were optionally equipped with bench or single seats. Of course, the tried-and-tested chain guard, consisting of a plastic chain case and elastic chain guard tubes, was used again. The ES was equipped with spoked wheels measuring 18 inches and tubular tires measuring 3.00-18. With an air pump and extensive on-board tools, the ES was well equipped at the factory for assistance on the road. Brackets were available as accessories.
In the course of their production, external and technical changes were made to the machines on an ongoing basis - partly in parallel to the other series. The paint scheme and the color range were changed in 1964. The cooling fins were enlarged in 1965 to improve thermal stability. The cylinder body, which was still reminiscent of the “ancestor” DKW RT 125, gave way to a “broad-ribbed cylinder”. The central float starter carburetor replaced the previous carburetor with air slide.  MZ gave the left cover of the gearbox an angular shape. In 1967 the shape of the turn signals changed. From 1968 there was a segment tachometer instead of the previous round tachometer.
1969 MZ revised the engines. By making changes to the intake system (air filter, carburetor, intake manifold), the exhaust, as well as the timing and compression, the performance could be increased.  At the same time, the carburetor cover was omitted. The tapered exhaust system gave way to a new diagonally cut exhaust. The series was now called the ES 125/1 Trophy and received the corresponding lettering on the tank. The reason for this was the six-time win of the WorldTrophy at the Six Days .
With the telescopic fork of the ETS 250, the tank from the Simson Sperber and another bench, the ES 125/150 Trophy then became the MZ ETS 125 in 1970. The production of the ES models was continued in parallel. Unlike the large ES models, the ES 125/150/1 Trophy remained in the range after 1973, parallel to the TS models, in order to continue to offer fans of the comfortable full swing chassis. With silver fenders, exposed struts, the flat seat of the TS, new colors and the new MZ logo on the tank, the models were given a sportier appearance. However, the production volume decreased. In 1977 the engine, which was basically from the thirties, was revised one last time. The bearings of the piston pin, the connecting rod on the crankshaft and the crankshaft have been changed in order to be able to use a 1:50 mixture from now on. In the same year, the production of the small ES models was finally stopped. 
In the contemporary endurance test over 12,000 km   the ES 150 (first version) could not quite meet the high expectations of a vehicle with the Q label. With the exception of a prematurely worn clutch, the engine, transmission and chassis were fault-free and showed no abnormal wear. However, it became apparent that some components could not withstand the relatively strong vibrations: two broken cables and three damage to the alternator each caused the vehicle to break down. The front fender repeatedly caused problems with cracking. Other defects related to the vibrations were the dysfunctional speedometer and various rattling noises. Other defects that occurred were a prematurely worn tire and a loosening exhaust manifold. In addition, there were regular problems with the spark plug (spark plug bridges),
The engine of the ES 125/150 had problems with the crankshaft journal (accessible from the right side). He "said goodbye" quite often after a sporty driving style, and the GDR workshops - often production cooperatives of the handicrafts (PGH) - knew this problem well enough.
ES models, 125 cm³
|IS 125||ES 125/1 Trophy|
|Years of construction||1962–1969||1969–1977|
|Displacement||123 cm³||123 cm³|
|power||8,5 PS||10,0 PS|
|Empty weight||115 kg||115 kg|
|Top speed||90 km / h||100 km / h|
In contrast to many other countries, the 125cc displacement class played an increasingly subordinate role in the GDR, as changed driving license regulations allowed driving 150cc machines with the driver's license available from 16 years of age. The 125 MZ models therefore made up a rather small part of total production, which was mainly exported.
ES models, 150 cm³
|IS 150||ES 150/1 Trophy|
|Years of construction||1962–1969||1969–1977|
|Displacement||143 cm³||143 cm³|
|power||10,5 PS||11,5 PS|
|Empty weight||115 kg||115 kg|
|Top speed||95 km / h||105 km / h|
MZ modified the engines of the RT 125 for the IWL in Ludwigsfelde as early as the mid-1950s . One of the modifications to the MZ engines was the expansion of the displacement to 150 cm³ from the Berlin SR59 scooter , as the heavy scooters with the 125 cm³ engine only achieved unsatisfactory performance. However, it was only with the ES that an MZ model with 150 cm³ appeared. Motors of the ES 150 were also used in the IWL-Roller Troll until the end of 1964 . The new price of the ES 150 was 2285 marks.
Total number of pieces
With 16 years of production, the ES 125/150 series is the longest produced series of MZ motorcycles. However, from 1974 only a comparatively small number of machines were produced parallel to the TS series. There is still uncertainty about the number of items produced in the entire period. The number of 900,000 mentioned in some publications must be questioned; Mainly because “only” about 500,000 machines of the TS 125/150 series were built in 13 years (1972–1985). From the data provided by the members of the MZ forum  (frame number + production date) it can be deduced that hardly more than 340,000 ES 150 and 125,000 ES 125 were probably built. A French publication speaks roughly in agreement of a total of 454,310 machines. The ES 125/150 series is one of the most popular motorcycles in the world.
- MZ ES 125/150/175/250. In: ostmotorrad.de. (Pages with operating instructions, spare parts lists, pictures, circuit diagrams and other information).
- Internet portal for the operation and restoration of MZ motorcycles, especially ES models. In: mz-es.de. (Pages with free download of original documents such as operating instructions, operating instructions, spare parts list, circuit diagram and repair instructions).
- Quality mark Q for MZ ES 125 and 150 . In: Automotive Technology . No. 7/1964, S. 273.
- ES125 / 150 - the new motorcycle series from MZ . In: Automotive Technology . No. 10/1962.
- Automotive technology tested MZ ES 125 and ES 150 . In: Automotive Technology . No. 11/1963, S. 426–430.
- rod needle roller bearings . In: Automotive Technology . No. 1/1964, S. 9–10.
- From the Leipzig spring fair . In: Automotive Technology . No. 4/1964, S. 124.
- First driving impressions with the MZ ES 125 . In: Automotive Technology . No. 1/1963, S. 25.
- MZ ES 125/150 with wide rib cylinder and new carburetor . In: Automotive Technology . No. 3/1965, S. 90–92.
- Further development of the small MZ series ES125 / 150 . In: Automotive Technology . No. 06/1969.
- MZ motorcycles ETS 125/1 and ETS 150/1 . In: Automotive Technology . No. 03/1971.
- Quality improvements on the MM125 / 150 motor . In: Automotive Technology . No. 09/1977.
- Double anniversary in Zschopau . In: engine year . transpress VEB Verlag for Transport, Berlin 1982, p. 36.
- Long-distance assessment of 12,000 kilometers with the MZ ES 150 . In: Automotive Technology . No. 9/1964, S. 349.
- Long-distance assessment of 12,000 kilometers with the MZ ES 150 . In: Automotive Technology . No. 12/1964, S. 465–466, 472–473.
- Long-distance assessment of 12,000 kilometers with the MZ ES 150 . In: Automotive Technology . No. 2/1965, S. 64–66.
- The most built German motorcycle ... In: mz-forum.com. Retrieved November 4, 2013 .
- MZ ES125–150 - Class Utilities . In: L 'Amicale des Motos MZ . fourth album. 1992 (French).