The 350 class, was, during the 70s at least, a level playing field performance wise whether at GP’s or on the domestic scene, with the vast majority of riders on board over the counter Yamaha twins, making the racing fast furious and above all very close. The Italians did their collective best to alter that situation even before the four stroke MV had passed its best with a whole variety of screaming two strokes, first of all came an adventurous Morbidelli square four and then the championship winning Harley Davidson’s piloted by Walter Villa. Despite the brief two year period when Villa reigned supreme the Japanese kept on winning with both Yamaha and Kawasaki proving dominant during the latter part of the 70’s and early 80’s. Then came the demise of the class in 1982 when the FIM streamlined the GP paddock forever eventually discontinuing four out of the seven capacity classes leaving just the three that we have today. During those final few years of the junior class there was one particular engine designer that showed so much promise and yet never fulfilled any of it, Franco Ringhini. The rule book of any sport can be a cruel mistress and when the changes were made to GP racing a whole host of promising 350cc designs, differing as they did, so much from the 250cc class regulations, were rendered extinct and hence redundant for all but club level competition.
The 350 Ringhini seen here is in reality a scaled up 125 Morbidelli engine with its twin disc induction situated on the end of each crankshaft and the ignition sat on top of the clutch primary gear way up high on the right hand side, mechanical economies typical of Latin thinking see the water pump driven off the opposite end of this timing shaft. Separate cylinder castings, held down by individual studs around the base, allow wider transfer ports to be cast in the barrel walls than with the Yamaha’s combined method of holding the head and barrel down with the same studs running the whole length of the top end.
Even by today’s high standards and treble figure horse power ratings, the Bimota framed Ringhini is a staggeringly fast and agile motorcycle, easily proving the match for your average road going sports bike, especially in its own environment of a billiard table smooth GP circuit. This is a purebred GP race machine and even at twenty three years of age, as such would shock most with its thorough bred performance, both engine and chassis wise. Despite what its aged looks might suggest, with around 90bhp on tap and weighing a mere 98 kgs, smack bang on the FIM minimum limit of the time, the power to weight ratio is actually better than any of the modern production Super bikes that we stand in awe of performance wise. The bulk of the weight is lost via the use of magnesium whenever possible and also within the design of the steel tube chassis. Bimota are still the leading exponents of this art and previous designs used tubing so thin that the whole lot had to be pressurised with gas and monitored while riding, via a gauge to indicate any cracking, and the subsequent crash, at an early stage.
Riding her steady in a foolhardy attempt to get better acquainted, is just not in the equation, she vibrates, feels fundamentally flawed, takes strange lines and quite frankly doesn’t handle at all well. It is as if the front is not connected properly to the rear, the ride is that bad. It is only when the gas is wound full on and the chassis is taught and almost ready to snap that it all starts to make perfect sense, the long travel, Yamaha monoshock unit, used for the rear has to be whipped into shape with the twistgrip before the back end is controllable, the Bimota frame is then as steady as a rock and one can begin to take liberties with it. Amazingly, and quite contrary to accepted chassis design thinking, the fork yolks are reversed with the fork legs actually sitting behind the steering head like some huge 150mph shopping trolley castor. None the less it works and this Bimota shares the same fine attributes of the rest of the family.
The engine comes into its own, pulling strongly above eight thousand and really takes off, in a light the blue touch paper and run, sort of way, up above nine before running out of steam just shy of the ten and a half mark, not a lot to play flexibility wise with but with six close ratio gears in the box you just have to keep stomping down on the gear lever until a corner looms ahead. Trying to keep up with the gear changing alone is enough to make you breathless such is the speed that the tacho’s redline is reached in every ratio, although as the higher gears are selected it does take a little longer to climb its way to the limit, but not that much so as to make it any easier!
Many people mistakenly refer to this engine as a simple clone of the TZ Yamaha, it does actually use the same mounting points within the frame, but in reality Ringhini only used the pistons, a few crankshaft components, gearbox and clutch out of the Japanese engine in a bid to save money during the construction. One must remember this is a back yard special at the end of the day not a factory-produced affair despite looking every bit like one. By cost cutting in this way the Italian designer did actually create an Achilles heel for the powerful and peaky motor, as the Yamaha box uses a first and second gear ratio that is simply no use for the Ringhini with a difficult spread in gear shifts that always compromises the art of getting out of slow corners comfortably. Of course GP tracks of old were mainly very fast and flowing affairs so back then the box probably made more sense but today circuits have far too many speed reducing chicanes and such like.
Luckily the fine handling Bimota chassis does allow for higher corner speeds to be safely utilised in an attempt at staying well up in the power band so the more sedate second gear can be used in preference to the wickedly capricious first.
Max revs in top gear, off the throttle and time to put in that request for those little grabbers to start earning their keep, which of course thankfully, they obediently do although a good four fingered squeeze is needed all of the way down to your peel in point. No niceties like adjustable span levers here just move your fist and grab a bigger handful. Once up and out of the fairing bubble, the magnesium Marzocchi front end handles the stopping experience admirably, enabling much of the speed gained during the previous straight to be carried through into the apex of the bend ready for that moment when the raucous throttle can be cracked open. Those slim and spindly looking Avon cross ply tyres just keep gripping, way beyond what most of us would call a safe angle of lean, and those unbelievably tiny twin piston Brembo brakes that grab the equally diminutive cast iron discs once again look ancient but bite and haul up just like anything that we have in modern times. Traction control is courtesy of wheel spin and the power band is something to do with Beelzebub himself. This bike has more power than the factory 1975 XR14 500cc Suzuki that Barry Sheene used to take his first GP win and it is lighter by some 30kgs!
One has to be brisk with the throttle as things down below do happen very quickly once the signal is given for the ponies to start to gallop, but on the other hand one must also pay due respect to the gods of the high side so as not to displease them as they sit looking at you from their vantage point on high, small but positive inputs are definitely the order of the day until on the way upright. The 18” Avon tyres may well be the benchmark by classic racing standards but this is not really a classic machine, just unfortunately borne well before its time. For a 350 twin this is among the most powerful ever and only topped in the junior class speed wise by yet another of Ringhini’s Pesaro projectiles, the scarcer still, square four, disc valve 350 of 1980.
Bimota Ringhini 350 Specification
- Engine – liquid cooled disc valve two stroke twin
- Capacity – 347cc
- Bore & stroke – 64mm x 54 mm
- Power – 90bhp @10,000rpm
- Torque – 47ftlbs @ 8750rpm
- Carburettor – 38mm Dell ’Orto
- Ignition – CDI
- Transmission – six-speed Yamaha dry clutch
- Frame – Bimota steel tube
- Suspension – 36mm Marzocchi forks. Bimota/Yamaha Monoshock rear
- Wheels – 18” Campagnolo front and rear
- Brakes – 250mm discs Brembo twin piston calipers, 220mm disc Brembo twin piston caliper
- Wheelbase – 1310mm
- Weight – 98kgs
- Top speed – 160+mph
Franco Ringhini
Franco Ringhini from Milan originally began working for the now defunct Guazzoni factory and while there designed many innovative and competitive race engines. Before too long he came to the attentions of Morbidelli. He went to the woodworking factory, labelled as test rider, designer and teammate to the number one rider and future world champ, Eugenio Lazzarini. Once established in the Morbidelli fold Ringhini became the man largely responsible for the early Morbidelli machinery leading the world in small capacity high performance two stroke power plant designs. No mean racer himself Ringhini carried on where the big Jap factories left off when they departed from grand prix racing in the late 60’s, utilising the disc valve induction to good effect. The Ringhini designed Morbidelli 50cc racer was the factories first successful GP machine and that was followed a year later in 1970 by the similar configuration125 twin, setting out, in the process, the basic design for the eighth of a litre class that would remain for nearly two decades with the inline, twin cylinder, water-cooled, disc valve induction engine being imitated by most of the manufacturers, certainly the successful ones anyway, within that period.
During the 72/73 seasons a new four-cylinder 350cc machine was being developed by Ringhini but many insurmountable problems with the design eventually caused a rift between the Morbidelli concern and their former star man. With the arrival of Jorg Moller as new designer at Morbidelli, Ringhini packed his bags and set up on his own in the bike racing business, and from his small workshop in that hot bed of Italian racing talent, Pesaro just south of Rimini, began building and forging the ideas contained within his head. He found the funding necessary to continue his four-cylinder design which eventually proved to be immensely fast and powerful, finishing fourth in its first ever grand prix although ignition problems, and the rule changes of 1982, prevented it from ever showing true potential.
Not to be deterred by mere rules, Franco simply created a 250cc inline twin by cutting the square four 350 in half vertically and making larger diameter bores to increase the capacity. The bike showed some promise but 250 racing had become big business with all of the major Japanese factories, along with Aprilia and suchlike developing phenomenally advance quarter litre missiles.
The designs he created were always brave, pioneering and most importantly, staggeringly fast. Being mainly hand built in small numbers, and with largely under funded development, Ringhini race bikes now rank amongst the rarest of all GP machinery from the last twenty years or so.
Bimota Ringhini 350 Twin Gallery
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