Moto·guzzi 875 Four
Moto·Guzzi 875 Four
Imp Power For A Sedate Custom Tourer
SPEED WEEK AT Daytona reveals some of the most exciting racing in the world, and also some of the most interesting motorcycles to be found. The two shows, one at the National Guard Armory, and the other at the Daytona Plaza Hotel, provide eager visitors with a multitude of sights to feast their eyes on. But perhaps the most interesting machinery is parked on Daytona's Main St., beside the curb.
When we first spotted D.H. Harwell’s Moto-Ciuzzi f our, we thought it was an Indian hour, but the machine was too long and modern in appearance.
Harwell, from the Cleveland. Ohio, suburb of Parma Heights, pist retired, built the motorcycle at home in his garage. He’d not been totally satisfied with either his Honda CB750 or his Moto-Ciuzzi V-7, so he decided to build his dream machine.
Having decided on a Roofes 875-cc overhead cam engine for the powerplant, he began modifying the MotoCiuzzi’s frame to accommodate it. This required lengthening the middle portion some 8 in. and welding on motor mounts.
Suspension modifications include the fitting of 10-in. alloy wheel rims and the installation of Honda CB750 front forks, which are 1 in. longer than the standard Moto-Ciuzzi units. A set of Ceriani rear suspension units now controls the swinging arm’s movements.
The engine, which comes to this country installed in the Sunbeam Imp automobile, was completely dismantled, and the beautiful aluminum alloy castings were glass-bead blasted to provide a satin-smooth finish. Wanting a slightly peppier engine. Harwood sent his camshaft to Weber in California and had a mild (35-P0-80-1 5 ) rework performed. He also obtained oversized inlet valves and smoothed and slightly enlarged the inlet ports for better high speed breathing.
The distributor was relocated to the rear of the cambox casting and was carefully mounted using O-rmg seals to prevent oil leakage. Ignition advance is now accomplished centrifugally from a static setting of 0 deg. BTDC’ to a fully advanced figure of 30 deg. BTDC at 2800 rpm.
Innovating as he went along. Harwell designed and built his own water pump and its drive, and again used O-ring seals to prevent leaks. A take-off from one of the main oilways lubricates the water pump gears, which were also handn~ade. Two automohile heater cores. suspended in home-made safety bars. serve as radiators. lOt~il water capacity is about 3 qt., hut the engine still tends to run too cool. Ni illed Irum a solid block t aluminum, the oil sump has a capacity of 3 (It.
Carburet ion is now handled by four 15/lb-in. Amal concentric carburetors, which are actuated by a single cable and rod assembly with individual adjustments. The Amals were settled upon after various other carburetor/log manifold combinations had been tried.
An aluminum adapter plate, 7/8-in. thick, joins the Rootes engine with the standard Moto-Guzzi transmission. The engine is rubber mounted, and its sideto-side torque oscillations are suppressed by a BMW steering damper. Standard gear ratios are retained, but the flywheel's weight has been reduced by 5 lb., and one of the two clutch plates was removed for smoother action. To make up for the loss ol clutch plate area, Indian Chief clutch springs were placed inside four of the Moto-Gu/./.i's springs to increase the clutch plate pressure. Clutch lever pressure is increased somewhat, but not enough to make it uncomfortable to disengage.
The Moto-Guzzi electric starter (which produces 3/4 hp) spins the engine effortlessly, and the 32 amp hour battery is retained. However, the battery now receives its charge from a modified Lucas alternator, (pirated from a Triumph b50), which is mounted on the front end of the crankshaft. Voltage regulation is accomplished using a Lucas Zener diode and heat sink.
Sedate and effortless best describe the 875 Four. 'Total weight is actually slightly less than a standard Moto-Guzzi V-7. Steering is remarkably light for so long a wheelbase, but the machine feels somewhat cumbersome at ultra-slow speeds. Once on the highway, however, the big Four loses its ponderous feeling and swoops through turns as surefootedly as almost any large touring bike.
Standard Moto-Guzzi brakes provide some 90 sq. in. of swept area, more than is needed to bring the machine down quickly from its high cruising speeds. Except for acceleration away from a dead stop, the transmission almost seems superfluous.
The Moto-Guzzi 875 Four is not only unique, but is exception smooth as well.
