Jawa 350cc Type 673 Replica

Frame no. KT1.0105059 Engine no. none

• Accurate copy of this legendary Czech two-stroke racer
• Engine professionally rebuilt
• Requires further restoration

If ever there was a Grand Prix racing motorcycle famous for all the wrong reasons, it is the notorious Jawa V4, which claimed the life of former World Champion Bill Ivy at the Sachsenring in 1969. Ivy crashed in practice when the temperamental Czech two-stroke seized at high speed, the bike and its rider sliding into an unprotected concrete wall.

The Type 673 350cc V4 was just one of a host of different designs drawn up by Jawa during the mid-to-late 1960s as its old four-stroke racers were pensioned off and a range of alternative two-strokes was developed. Designed by Zdenek Tichy, the Type 673 was effectively two twin-cylinder engines of 48x47.6mm bore/stroke mounted one above the other on a common crankcase at a narrow included angle, the two crankshafts driving a large primary gear and thence the seven-speed gearbox. Water-cooling was employed, with circulation by the 'thermosyphon' principal, there being no pump. MZ had shown that disc valves offered an effective route to increased power and this form of induction was adopted by Jawa, while ignition was controlled by four separate sets of contact breakers. The compact V4 engine was carried beneath a tubular steel frame, the lower pair of cylinders being horizontal.

As if portending what was to come, the 350cc V4 made an inauspicious race debut in 1967 at the Dutch TT where, ridden by Gustav Havel, it repeatedly seized in practice and retired from the race for the same reason. The rest of the '67 season and most of 1968 were taken up with further experimentation to achieve a measure of reliability, one of the first developments being the fitting of a pump in the cooling system. These efforts began to pay off in the second half of 1968; works rider Franta Stastny achieving a number of top-six finishes in Grands Prix, the highlight being a 3rd place behind Giacomo Agostini's all-conquering MV Agusta at Brno.

Following Yamaha's withdrawal from Grand Prix racing at the end of 1968, Jawa recruited Bill Ivy, 125cc World Champion for the Japanese factory in 1967, to head its rider line-up. After an inauspicious debut at a non-Championship meeting at Cesanatico, where the bike seized, Bill bounced back at the Hockenheim round of the World Championship, harrying Agostini's MV on his way to a fine 2nd place, with Stastny on another of the Jawas 3rd. By this time the V4 was running electronic ignition; maximum power had been raised to 70bhp, putting it on a par with the three-cylinder MV. At the next round contested, the Dutch TT at Assen, Bill had passed Agostini before the Jawa slowed, eventually finishing in 2nd place. Thus it was with a keen sense of anticipation that the Czech team arrived at the Sachsenring, only for their hopes to be cruelly dashed.

Jawa's hopes of Grand Prix glory effectively ended with Bill Ivy's passing. Yet despite its fearsome reputation there was no shortage of riders willing to race the V4, which was the only credible rival to MV Agusta in the 350 class. The likes of Jack Findlay, Ginger Molloy and Silvio Grassetti all raced the Czech two-strokes with some success, Grassetti's 2nd place at the Italian Grand Prix in 1969 being the best result achieved. When the FIM banned multi-cylinder engines from the 350 class at the end of the '69 season, the Jawa V4's career was effectively over.

According to information kindly supplied by Arnost Nezmeskal of the National Technical Museum in Prague, only three complete Type 673 racers were completed by the factory in period, plus two spare engines. All three bikes survive and are known. There was no factory bike sold into private hands except the sole example now in a private collection in Germany, currently on display at the Top Mountain Motorcycle Museum, Hochgurgl, Austria.

It seems probable that the machine we offer is one of the early replicas made by Mr Fiala in south Bohemia. In the late 1970s or early 1980 his Tabor-based MAS company concluded an agreement with Jawa permitting them to make a copy of a Jawa Type 673 engine. That engine was mounted in their own frame, and they used castings of original Jawa hubs. Mr Fiala raced his MAS 350 in the early 1980s in Czechoslovakia. Fiala's Jawa replica was later sold to France and further improved to make it look more like the original. In 1991 it was sold by noted collector Michelangelo Pochettino, a Jawa-CZ importer in Italy, before being purchased by a UK collector in 2014. Fiala later made more such copies, although precisely how many is not known.

The machine offered here has benefited from the expert attention of Jawa specialist Roger Henderson, who found that the engine was seized solid, the cause being a severely corroded water pump, which had locked the engine. Further inspection revealed a cracked clutch pressure plate, severe internal corrosion to the water passages, corrosion in the gearbox section of the crankcase (which had caused a hole), and various wrecked bearings. Judging by the corrosion in the water passages, which were full of plain water with no inhibitors, the bike had been standing for decades. It took a considerable time to dismantle the engine completely as so much damage was present.

A regular report and update was made to the then owner, who asked Roger Henderson to rectify matters. Obviously, parts for the Type 673 are rare if not non-existent. A new water pump casting was made and machined to specification (original with the bike) and various new studs and fasteners made as the originals were of several non-standard sizes. The cylinders and pistons were scored so new liners were made and fitted. KTM con-rods and pistons were used. The engine was reassembled with much help and advice from BDK Engineering, which is about the only concern with knowledge of these machines.

At this point matters came to a halt when Administrators were appointed to run the owner's company. Subsequently the engine was reinstalled in the frame, and the carburettors and exhausts refitted together with the tank, seat and fairing. Nothing has been done to the rolling chassis, suspension, brakes etc, so all this will need attention, as will the carburettor settings and cooling system plumbing (the original brief was to leave the cosmetics strictly alone.) Sold strictly as viewed, this well-made Jawa Type 673 replica will surely be welcome at any gathering of historic racing motorcycles.
Key not required