A few things about names you Dneed to know...
KMZ and Dnepr can be used synonymously and interchangeably, as can IMZ and Ural. However, most folks follow the convention of applying the names Dnepr and Ural to the newer overhead valve (OHV) bikes from the respective factories and reserve KMZ and IMZ for the older sidevalve (SV) flathead motorcycles. KMZ is the Ukrainian factory near the Dnepr River translates to Kiev Motor Works. IMZ is the Russian factory in the Ural Mountains and means Irbit Motor Works. So...
Dnepr = KMZ = Kiev = Ukraine
Ural = IMZ = Irbit = Russia
And a few other definitions...
RPOC- (Russian Piece O' Crap) is a term of endearment applied frequntly to all Soviet bikes regardless of make or model.
Foilhead- is a RPOC rider/driver.
Solo- a motorcycle without a sidecar
Hack- is any sidecar. Most all of the KMZ and IMZ production was motorcycles with a hack included. You'll see like 20 bikes with a hack for every one Ruskie solo.
Flying the chair- is a manouver where the sidecar wheel is lifted from the driving surface, often unententionally on a hard right-hander.
Monkey- is a sidecar passenger.
SV- sidevalve. This is the older model engine with valves built into the head, parallel to the cylinder bore. 750cc only.
OHV- overhead valve. The newer motor easily identified by the two parallel steel sleeves visible on the top of the cylinder heads. Available from KMZ only in 650cc. Available from IMZ in 650cc until about 2002 when the 750cc engine was introduced.
Swingarm- a Russian improvement in rear suspension with shocks.
Plunger- the original rear suspension design
Leading link forks- a front suspension improvement specifically for sidecar operation. Think of it as power steering for a hack rig. The newer leading link (LL) is not generally suitable for solo use.
Top speed and reliability...
If you are looking for a "gas-n-go", high-speed autobahn sort of Japanese bike, you've come to the wrong place. If you are shopping for a backroads, eye catching cruiser, you are getting warmer. One must remember, especially on the older models, the technology is 70 years old and the metallurgy is Russian. They can be made into reasonably reliable daily drivers with some work, however. Requisite for long life, is a proper break-in with frequent oil changes and speed variations with no overloading.
The newer Urals are approaching the "gas-n-go" stage with minor scheduled maintenance and tinkering like setting valves and balancing carburetors. Don't let that scare you, though, it's not as hard as it sounds. These are seriously robust machines with maintenance akin to keeping a lawnmower or tractor running. There are very few instances that require whole engine or gearbox replacement. Most things can be repaired by a person with moderate mechanical skills and some horse sense. Repairs are generally straight forward with no hidden suprises.
The top speed for an old sidevalve powered rig is about 60-65 mph. The cruising speed is about 50 mph. Add about 10-15 mph for the newer overhead valve models.
Where and what to buy...