Yamaha CS3 1972 rabbit hole

[IR8D8R]

 Looking at an engine with heads that look similar to an RD 200 on a case stamped CS3.

On the often-wrong internet I find 2 different 71-72 CS3 200 motorcycles from Yamaha and a CS5E that was a direct predecessor for the reed-valve RD 200 in 1973.

71-72 180cc piston port CS3 with a older style Yamaha tank design and cylinder head, and another CS3 that looks more like a R5 or DS7 down to the slab-sided DS7, R5, RD-style heads with piston port shown as both 71 and 72.   

At some point the engine was enlarged to 195cc. Were the 195cc all CS5E? I have seen the more archaic looking CS3 listed as a CS3E with the updated styling shown as "CS3".

I have seen both versions online tagged as 71-72. Was Yamaha selling 2 versions of the CS3 those years? Or has someone transplanted the topend of a CS5E onto a CS3 case?

I'm very confused.

IR8D8R

[m in sc]

ive never been able to keep up w it, either this si def a socal250 topic.

[SoCal250]

The CS3 and CS5 are both 200cc (195cc) piston-port models with electric start (and kick start). All of them have an engine number beginning with CS3-
The CS3B is a low exhaust model. The CS3C is a high exhaust scrambler version. I believe the CS3 was only made as a 1971 model (people may ID them as 1970 models due to the build date stamped on the frame ID tag)

Engine #
CS3C = CS3-0xxxxx
CS3B = CS3-1xxxxx
CS5   = CS3-2xxxxx

The top photo you posted looks to be an older model, and likely a UK/Euro version or possibly Australian? I'm not even sure it's a CS3, the shrouded shocks are different than a CS3 and it's the wrong color (when comparing to US models). US versions were Metallic Purple (CS3B) and Candy Green (CS3C). It may be a CS2, which was not sold in the US, (AFAIK).
The bottom photo is a 1972 CS5. In fact, I have one sitting on my lift right now.

EDIT: Some of my vintage Yamaha tech bulletins refer to the CS3C as a 1970 model and the CS3B as a 1971 model. Which makes sense, considering the engine # assignments, based on sequence.

[BlueR32]

Back in my early years in Dublin Ireland I owned a CS3 exactly like the early pic above. It was not in great shape when I got it and there was a hell of a rattle from the engine. Not the usual piston slap. The crankcase was vertically split so it was an interesting and challenging tear-down/rebuild. Turned out there was an aluminum filler block between the two halves of the crankcase that had worked itself loose. Need less to say it ran like sh1t until I fixed that. Loved the electric start though!
I do remember a Yamaha 180 CS2E that looked exactly the same except the mufflers were slash cut at the ends.
https://www.youtube.com/watch?v=e0FbILPeNX0

[IR8D8R]

Thank you gents. A guy was selling an engine as an RD250. Clearly it was not. Cases stamped CS3. Piston port. Not an RD 200. It was cheap.

I tried looking up to figure out what it was. I assumed the immediate predecessor to the RD200 Electric. That made sense but as far as displacement I found different info depending on year.

Yamaha seems to have begun the changeover to the "RD-style" cylinder head in 71, contemporary with the R5 and DS7. But the photos I could find for the 70-71 CS3 didn't match what was on the engine. Definitely a lot of CS3's shown as 1970 MY. Hmm, maybe its CS3 cases with the later topend? ...Explained by CS5 cases still having CS3 stamping. That makes sense. I think the engine must be a CS5 then.

All because I tried searching "CS3". I read an article that said the CS3 was 180cc raised to 195cc but another that said the 180cc was a CS2.  I didn't even notice the scrambler version.

Much history will be lost because the internet has allowed so many writers with Jethro Bodine educations to publish whatever they want online, paid by word count and translated by North Korean AI. SMH.

IR8D8R