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

[Egor]

All the Russian engines are rotary valve. that might be the cause of the gutless performance. I would like to see the end of the crank and see how large the hole in the end of the crank is. Yamaha used a rotary valve in the early bikes, but it was a flat disc and gave the best performance ever for a two stroke. I think you could modify the intake timing on the Russian versions and get better performance. You could blank off the intake and put the piston port barrel on also, it would be interesting to see if it would fit. I saw on some of the racing Russian engines they install a reed system and the things seem to fly with that. There are a lot of ways to put induction on a two stroke. I would like to see Dagger comment on the racing version. I think Hammer was posting vids of the racing. Have fun, Dave

 

[850 Combat]

All the Russian engines are rotary valve. that might be the cause of the gutless performance. I would like to see the end of the crank and see how large the hole in the end of the crank is. Yamaha used a rotary valve in the early bikes, but it was a flat disc and gave the best performance ever for a two stroke. I think you could modify the intake timing on the Russian versions and get better performance. You could blank off the intake and put the piston port barrel on also, it would be interesting to see if it would fit. I saw on some of the racing Russian engines they install a reed system and the things seem to fly with that. There are a lot of ways to put induction on a two stroke. I would like to see Dagger comment on the racing version. I think Hammer was posting vids of the racing. Have fun, Dave

Kawasaki. Suzuki, and Bridgestone all used rotary valve. So has Rotax. All the rotary valve engines I have worked on hve a large disc valve with the carb mounted with the throat paralell to the crank shaft. Usually they were faster than piston port engines in their class.

As far as I know, the earliest Yamaha 2 stroke was a copy of a pre WWII DKW 125, where Schnuerle designed it. Harley built copies of this engine, the Hummer, BSA did as well, the Bantam. Royal Enfield also built copies of it.

 

[Allen_Wrench]

Gee. Is it just me, or are the Russian engines prettier than the China Girls? I don't know if they run better but I certainly think they look nicer.

 

[Dan]

I'm wit you Allen

 

[GearNut]

Yeah, I think that they look alot better that the chinese ones too.

 

[Dave31]

Yes they are rotary valve and are way better looking then the Chinese and assembled much better. Been too busy to take a spin on one, there might be one racing at the Death Race but we will have to wait and see.

I do know one will be torn down and built back up with a little performance work done to it. Hopefully I sneak some photos of the motor torn down.

 

[john_the_great]

Some of Kawasaki's rotary valve bikes did very good in the 70's that was kinda there trademark cuz almost all of there bikes were rotary valve(not the triples or the big streetbikes or the 250). Rotary valves can be tuned to perform and don't cause as much intake drag as reeds. The reason they went out of fashion is because you had to mount the carb in weird locations.

 

[Egor]

Yea I had a 62 Yamaha Omaha 55 and a 80 I don't remember the model. They both had the rotary. All the small model engines have the same valve as the Russian engine. I have one of the D&R engines with one also. I think MZ had a rotary disc they put on top with some gear drives to spin it, racing only. Fair looking forward to see the end of the crank and see how big the hole leading into the crankcase. Have fun, Dave

 

[Cabinfever1977]

Heres a link to the russian engine:
http://www.grubeeinc.com/USA/RUSSIAN M21 INSTRUCTIONS.htm

 

[Bombardier]

we had one of the russian bicycle engines here is australia but it was reed valve rather than a rotary valve. we stripped it down hoping to modify the disc valves timing only to find reeds .

 

[john_the_great]

This motor doesn't look like a classic rotary valve engine... they usually have the carb mount more to the side of the case

 

[Bombardier]

the bonus with crank case reeds is the motor can breeth when ever it wants and for as long as there is vacume air fuel mix will enter the crank case and performance is dictated by the transfer ports , exhaust port and exhaust pipe and carb. we tried modifying a old chinese bicyce engine to case reed induction and used the origional inlet port as a third transfer port .we put a big gokart carby on it and it went like the clappers until the liquid steel glue broke and siezed it solid. there wasnt realy enough roon in the back of the case for the inlet port .next time we might put the inlet to the crank case under the engine as there is plenty of room under the crank case for a reedblock and inlet manifold but the big end isnt realy strong enough for too much HP and as i mentioned before unless ya run methanol or ethanol they run way too hot and will sieze eventially. they are what they are and i guess the guy using different barrels has the right idea .i still like the idea of using a early garelli alloy chrome bore barrel and head as they have huge finning and look more like a 100 than a 50. it all comes back to time and money

 

[Dave31]

Here some pics of the Russian motor mounted.........

 

[2door]

Here some pics of the Russian motor mounted.........

Fair,
The drive chain looks small. Is it bike chain?
Tom

 

[Dave31]

Fair,
The drive chain looks small. Is it bike chain?
Tom

No it is not a Bike Chain Yoda, I believe it is a 415 chain.

This bike may be raced at Death Race coming up here soon. The bike is a old Schwinn with a freewheel on the crank.

 

[Down_South]

What kind of spark plug are they using on the Russian Ds? Is it the same type of plug that comes with the Chinese engines?

 

[Spike1401]

I also have such a russian engine over here in Germany. It was not sold as a bicycle engine but mounted to a moped called Riga 13 or Riga Diana. I bought it from the municipal court of Stuttgart but nobody there could remember where they get it from. It was stored there for a long time and seems never used. It starts and run good but have very low power. Maybe the ignition is not set up correctly because I cant read the manual. I hope somebody can tell me the correct ignition point befor TDC and the right pointer gap.

 

[silverbear]

Spike1401,
Looks like a pretty cool setup. 1957 the tag says. Very nice condition. I wonder if porting would help. There must be ways to boost the power output. Nice find!
SB

 

[Spike1401]

Porting would maybe help but its not a real option for me beause I want to keep it original, I dont use it in daily traffic.

 

[biken stins]

Spike1401.
Got mine fired up today. Noticed very low power. Turns out it was the throttle conection. Never had seen any thing like it. very interesting. Might try pulling the cable by hand to see if the rev's increase. If not take cable out and see if slant is pointed to front. Other than that I don't have a clue. It runs fine now. It is a truely smooth running engine. Good luck.