The origins of the engine

[robe]

A good thread on this topic.

The Russian engines D-4,D-5,D-6,D-8. History.

I will tell about engines of the Russian manufacture which use in Russia for installation on a motor-bicycle. These are engines D-4, D-5, D-6, D-8, at present, they are not made. The factory which made engines is called ,,Krasniy oktyabr". Them exhausted since 1957, till 1990... So D-4 and D-5...

motorbicycling.com

A build thread using a D series engine. Thread 'Russian engines' https://motoredbikes.com/threads/russian-engines.3881/

While I agree with the changes in design, mostly due to the fact that it cut costs, these engines did lose some charm. Did gain a good bit of power though.

If only the cut cost went right back into quality control...

Thanks for the link! That is good history of the origins of the CG. Grubee fits in there somewhere.