Originally posted by Wolfie665 Unfortunately I haven't got any pictures of my old bikes I've lost all my film photos archive before digital era
Anyhow my Jawa was old 350/634 model and I've got two MZs the same model ETZ250 in black and blue. MZ was supposed to have better brakes, but stopping was real long term planning job especially in wet
Stock photos:
The Jawa 350 twin, 2 stroke was quite a motorcycle. It was around for decades and was quite a good machine. Not extremely powerful, but still a solid performer, very durable, reliable. I never did get one, but I was interested in them when I was a young motorcyclist in the 1960's. A buddy...not a very big guy , had one and I was always surprised how well it accelerated. It wasn't a high horsepower job, around 18-21 hp, but it did have plenty of bottom end and mid range torque for it's 350cc displacement. Like many street CZ and Jawa motorcycles revving it to the redline didn't make much difference, it made more sense to shift it when it plateaued...guessing (no tacho) that would be around 5-5500 rpm.
In contrast my Yamaha YDS3...was a high horsepower 2 stroke, 250cc twin....28.6 @ 8600 rpm or so. Not much power at low rpm's but when you revved it over 5-6000 rpm (it, unlike the Jawa/CZ's...had a tachometer) it would come on strong right through to the redline, from my recollection of 50 years or so ago.
When I think about 1960's high performance 2 stroke twins , I automatically think about the Yamaha and Suzuki engines of the time. My understanding is that although their high performance abilities were developed by their engineering, there was obviously, IMO, a strong contribution in 2 stroke twin design from the Adler250 and Jawa 350 twin cylinder 2 strokers. Engine layout seems to share some design points, in my non engineering, eyes .
Also MZ , as mentioned before made significant inroads in 2 stroke engine exhaust timing and exhaust pipe performance design, etc...which upped performance potential in 2 strokes significantly/performance.
I think there is a lot of credit that is due to the Eastern and Central European motorcycle engineers and factories...that is not generally acknowledged.
The MZ in your picture has unusual barrel/head finning. Quite a bit when you think about it, but I would think that those relatively massive fins would dissipate heat away from the engine quite well, keep it from overheating and therefore contribute to reliability/durability.
Thanks for posting those photos...they brought back a lot of memories for me, particularly the Jawa twin.