Croz capers
Kiwi TT-winner Graeme Crosby has fond memories of his Kawasaki A7 Avenger (and a 44-gallon drum).
“It was my first real production racer. I bought it from my mentor Eric Bone at a bargain price of NZ$650 in 1972. It was a quick and nice handling road bike with good ground clearance and a special engine noise that only disc-valved engines made. Although older and perhaps not as refined as the more modern RD350s, I didn’t have to worry about the carburetor slides jamming wide open or being thrown off because the foot pegs touched and dug in. In one of my first races on the A7 I rode to a brilliant 2nd place behind Dale Wylie and was followed home by a 44 gallon drum in 3rd place! The drum followed me over the line as a result of me running off the track. When I got back on the track I got tangled up with the 44 gallon drum and the rope that was supposed to hold the crowd back.” a neat cast-alloy case that led back to a large capacity paper air filter which sat across the top of the crankcases – where the carburettors on a normal piston-port engine would be. Inside these cases sat more original thinking, for the electrics also lived in here, with a constant flow of cooling air running over the alternator. The usual ‘roar’ from a multicylinder two stroke was nicely muted on the A7. A gear-driven generator, running at half engine speed, produced the current for the twin sets of points which were mounted on a plate on the end of the generator, running at 23º advance. This was deemed to be a superior arrangement to the method of mounting the points on the end of the crankshaft where flexing and fluctuations in timing can occur. The drawback of the design is the inherent width of the complete engine, which is more a problem on a racer than on a road machine. Later disc valve designs, such as can Am, moved the carburettors from the end of the crankshaft to behind the engine, with a tract back down to the disc valve to feed in the mixture. It was this excessive width that forced Kawasaki to abandon their disc valve design when producing the H1 and the subsequent range of triples, as the task of feeding the centre cylinder via a disc valve while containing the width would have proved insurmountable.
In one respect – that of lubrication – the 350 engine differed from the 250. On the 250, oil was mixed with straight petrol by injecting it into the inlet port, where the action of the crankshaft effectively mixed the oil and fuel and distributed it to the bottom end bearings and the walls of the cylinders. On the 350, the same mixture process was supplemented with direct oil injection to the outer crankshaft main bearings (the two inner bearings retained oil mist lubrication) and the big ends of the connecting rods. This system had been pioneered on the racing A1R, and was given the marketing title of Kawasaki Injectolube. Early road tests of the A7 invariably compared it with the 250, and while the performance of the 350 was universally applauded, ‘Vibration” was a word that cropped up often. For this reason, the handlebars are rubber mounted, although the engine is not. Excessive fuel consumption was another gripe, although it was noted that the Avenger seemed happy on the standard grade of petrol available at the time. Perhaps it was the stronger springs fitted in an effort to tame the torque, but the clutch also quickly gained a reputation for dragging, making finding neutral when stopped a tricky proposition. The five-speed gearbox had neutral at the bottom of the range, rather than between first and second. In terms of comfort, the A7 gained full marks, with its large, plush seat and high, wide handlebars. Brakes – 180mm front and rear – were also highly praised, although the suspension was on the stiff side, perhaps a throwback from the racing models. That torquey engine also drew much admiration. Although the main power band extended from 6,000 rpm to 9,200, the engine would pull cleanly from as low as 2,000 rpm. Although maximum power was listed at 7,500 rpm, the engine could be buzzed well past this, resulting in some testers achieving as high as 107 mph (173 km/h) at 9,200 rpm, but a happy highway rate of 75 mph meant the engine was just loafing along in the lower end of its rev range. Acceleration was where the A7 really drew rave reviews, turning 14.4 seconds for the standing quarter mile with a terminal speed of 94 mph – the domain of 500s and even bigger stuff. A year after the release of the A7 came the A7SS – a Street Scrambler in the style much favoured by the American market. It was no coincidence that the Honda CL77 (street scrambler) was at the time the biggest selling motorcycle in USA, and it was priced almost $200 less than the US$845 A7SS. In reality, there were few changes on the SS apart from the high level exhaust system which ran on the left side and was fitted with a perforated heat shield. In 1969 the battery/coil/points ignition system gave way to a Capacitor Discharge (CDI) system which included a system that increased voltage to reduce unburned fuel. Kawasaki worked quickly to implement the CDI system and refine it, knowing that stringent US regulations concerning exhaust emis-