The K-650 was the first KMZ motorcycle to be called simply “Dnepr”. Introduced in 1967 (the Russian history dates it to 1968), it replaced the side-valve K-750M with an overhead-valve 650 cc boxer, a crankshaft on plain bearings and a top speed of 100 km/h.
Dnepr K-650 at a glance
| Maker | KMZ, Kyiv |
|---|---|
| Production | 1967–1971 (Russian sources: from 1968) |
| Also known as | MT-8 |
| Mass | 315 kg |
| Engine | 650 cc OHV flat twin |
| Power | 27 hp at 5,000–5,200 rpm |
| Torque | 4.7 kgf·m |
| Electrics | 6 V |
| Gearbox | 6204, four-speed |
| Fuel tank | 21 litres, A-72/76 |
| Seat | separate |
| Top speed | 100 km/h |
The K-650 is described in the English and Russian histories of the Dnepr marque; this page uses those sections.
History of the Dnepr K-650
Why KMZ needed a new engine
The side-valve K-750M had shown where its weakest points were. Its assembled steel crankshaft and cast-iron cylinders lasted no more than 20,000–25,000 km, and the plant wanted a motorcycle that could go much further between overhauls. The engine design bureau led by N. A. Ovcharenko prepared the first overhead-valve 650 cc prototypes in 1960. Between 1963 and 1966, with the foundry department of the Kyiv Polytechnic Institute, KMZ worked out a crankshaft cast in shell moulds from high-strength cast iron; tests showed almost no wear of the journals after 40,000 km, and the new crankshaft raised the engine life to 1,000 hours.
A modern engine for 1968
The production engine was a 650 cc overhead-valve flat twin. Its crankshaft ran on plain bearings, the cylinders were bimetallic with an aluminium finned jacket and a cast-iron sleeve joined by diffusion, and the valve gear was overhead instead of side-valve. The result was 27 hp at 5,000–5,200 rpm and a maximum speed of 100 km/h. The first industrial batch was released on the eve of the fiftieth anniversary of the October Revolution, and the model was the first to carry the name Dnepr, although the designation K-650 was still used alongside it. The factory also called it the MT-8.
In service
The K-650 kept the separate seats, the 21-litre tank and the 6-volt electrics of the previous generation, and it was built as a sidecar outfit. Its overhead-valve engine was strong enough to remain in production until 1971, when it was superseded by the MT-9. That model kept the same 650 cc layout but added a gearbox with reverse and a little more power. The K-650 therefore stands at the point where the Kyiv line separated itself from the side-valve M-72 and K-750 family.
Design and features
- Overhead-valve 650 cc boxer: KMZ’s first OHV engine, with 27 hp and a top speed of 100 km/h.
- Plain-bearing crankshaft: a cast-iron shaft that raised engine life to 1,000 hours and resisted wear far better than the old assembly.
- Bimetallic cylinders: aluminium fins with a cast-iron sleeve, joined by diffusion.
- First Dnepr name: the model that gave the whole KMZ heavy motorcycle line its name.
Dnepr K-650 versions
- K-650 (1968–1971): the standard production model, also called MT-8.
- K-750M: the side-valve predecessor it replaced.
- MT-9: the successor, with a reverse gear and 32 hp.
The K-650 followed the side-valve M-72 and was replaced by the MT-9. More models are in the Dnepr collection.
Video: Dnepr K650
Video by Ádám Attila on YouTube.
Sources
- Dnepr (motorcycle), English Wikipedia: launch, OHV engine, successor
- Днепр (мотоцикл), Russian Wikipedia: engine development, specifications
