ROLLING HIS OWN

Maurice Ogier is one of those people who is completely uninterested in racing cars or bikes that other people have built – he has to roll his own. He therefore scorned creating an outright racebike with a Spondon or Harris frame wrapped around a tuned-up motor fitted with the factory race kit, but opted to do it all himself, using the standard streetbike frame. The Laverda factory had in the meantime produced its own 600cc kit for TT Formula 2 racing, developed in conjunction with ex-works rider Augusto Brettoni, by then the leading tuning specialist in Italy for the Breganze company’s twins and triples. But Maurice declined to use any parts from this race kit beyond the valves, firstly on the grounds of cost, but more importantly because he thought the pistons too heavy and prone to having the gudgeon pins pick up inside the piston. To uprate the Laverda engine, an eight-valve parallel twin with 180º crankshaft which in standard F500 form produced 53bhp at 8900rpm, Maurice ported the Laverda’s dohc cylinder head, fitted the oversize valves out of the factory performance kit (29mm inlets instead of 27, and exhausts up to 27mm from 24), and reshaped the combustion chambers to his own specification. He fitted a set of pistons specially made to his own design by Mahle, which still entailed skimming 90 thou off the cylinder head, to lower the deck, and get decent combustion. Initially the bike ran on a 10:1 compression ratio, but later as development unfolded this was raised to 11.6:1 using 90% Avgas, requiring a close watch on valve to piston clearances, and usually entailing a bent set of valves if a gear was missed. The wisdom of this decision was duly proved by our bike’s reliability, so while Brettoni’s semi-works bike tended to be fast but unreliable in TT F2 races in the hands of Italian hill climb champion Stefano Pagnozzi, requiring a complete new crank assembly every 500 miles/800km – and esteemed Classic Racer editor Malcolm Wheeler and sponsor Cleve Brightman suffered numerous expensive blow-ups on their Harris-framed bike, which was our only Montjuic-based rival in British F2 races – the Ogier Laverda ran more than 4000 miles/6500km during the three seasons I raced it without a single mechanical retirement. The only time it failed to finish a race was when I fell off it at Brands Hatch in the BOTT race there in 1984 after grabbing fourth place from the works MKM Krauser-bmw of Paul Iddon and was close behind Stu Jones’ RGB Weslake, intending to snatch third place off him, but when he missed a gear I grabbed too big a handful of front brake to miss him and landed on my ear, breaking the footrest. Inevitably, Maurice Ogier soon acquired semimystical powers in the eyes of laverdisti for producing such competitive power so reliably, but as so often his secret was rooted in sound engineering practice. In making its 600cc engine kit, the factory (or Brettoni) had gone for the maximum overbore on the original 72 x 61mm 497cc engine, fitting 78.9mm bore pistons for 596cc. Ogier reasoned these were far too heavy, especially in view of the short stroke and high revs, and indeed after a little additional work, his 77.8mm bore Mahle pistons delivering 572cc were actually 36 grams lighter each than the standard 72mm bore 500 pistons. Liners for a 350cc Weslake grass track engine were machined to suit, and the stock F500 camshafts retained, albeit fitted with modified timing-chain wheels offering a Vernier adjustment to allow Maurice to experiment with alternative valve timing. The crankcase was adapted to plumb in an oil cooler, essential in view of the substantial extra heat generated by the tuned engine, and this plus the fact that the Laverda was religiously run on Castrol R vegetable oil was another major factor in its reliability. This allowed our high mileage without any noticeable camshaft wear, whereas Brettoni told us he was replacing his every 500 miles/800km. Instead, the only components ever replaced in the Ogier engine in the three years I raced it were piston rings, a new set of valves after I missed that gear exiting Union Mills in the 1983 TT, and a precautionary new crank fitted for our 1984 transatlantic foray to Daytona. It used the original valve springs its entire racing life. Maurice also lightened the crankshaft by machining both starter and generator splines off it, instead fitting a self-generating Kröber electronic ignition, saving just on 10kg. The Kröber was incredible, providing such a good spark that the bike could be started from cold on very hard NGK 11-grade plugs without them fouling – it would even run at 2-3000rpm on constant throttle while warming up the Castrol R. The NGKS deserve a plug (sorry!) too: we used the same pair with no problems for three seasons. An indication of the excellence of the Ogier-modified combustion chamber shape came from the fact the ignition timing could be moved around anywhere between 30-35º without any variation in power output.

“THE OGIER LAVERDA RAN MORE THAN 4000 MILES/6500KM DURING THE THREE SEASONS I RACED IT WITHOUT A SINGLE MECHANICAL RETIREMENT.”