(13-07-2009, 01:28 PM)Malcolm Wrote: 350cc or 500cc ?

UPDATE

Taken from an enthusiasts website.

Unfortunately, also the powerful and beautiful "Typ-673" four cylinders (four pics above) -always two strokes, 80 hp, 270 km/h in the last version of the 1971!- was a "killer bike": the great English rider Bill Ivy lost his life because of the same cause (the seizing of a piston, that caused the blocking of the bike).

Unfortunately, the quality of the steel used for the engine was very poor, and caused these tragic events. This was a shame, because the "Typ-673" was the highest Jawa's expression for the GP competitions, with an advanced liquid-cooled V4 engine equipped with rotating valves (technology used also by the MZ).

After these accidents, the Western drivers left the Czechoslovakian team, although the bikes were competitive and fast.

Sorry for being picky, but I would like to put one or two things right...
-the engine failure wasn't caused by a seized piston, it was either a cracked big end or crankshaft bearing (some rummaging would be needed to find a copy of the officicial FIM report of the meeting which was shown in a German mag some years ago)
- the Jawa team mates were Ivy and Stastny before the accident, no additonal western riders. After the accident, J. Findlay (2 rides resulting in 2 crashes...) and Silvio Grassetti (both western of course) took over, Silvio with some success, winning the Yugoslavian GP and finishing 2nd in Italy
- 80 HP looks a bit too much IMHO. Bill once stated that the performance was comparable to the 250 cc Yamaha, roughly 70 HP
Regards