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http://www.hondaprokevin.com/2018-honda-gold-wing-tour-review-specs-changes-touring-motorcycle-dct-automatic-bike
Engine
Honda’s iconic, liquid-cooled, horizontally opposed six-cylinder engine remains the heart of the 2018 Gold Wing, and is updated this year to be more compact, more fuel efficient and more versatile in varying riding situations. Key to this newfound size and performance are an updated crankshaft, valve train, and intake system.
The cylinder bore is down 1mm, from 74mm on the previous-generation Gold Wing to 73mm on this latest iteration, while stroke is 2mm up, from 71mm to 73mm. For a more compact overall package, the crankshaft is now formed from a high-strength SCM440H steel alloy material that enabled engineers to achieve a thinner crank web and 9mm reduction in the distance between cylinders, from 90mm to 81mm. Left and right cylinder offset are reduced by 4mm. Meanwhile, the position of the crank pulser (which detects the engine speed and the piston positions, for controlling fuel-injection quantity and ignition timing) has been moved from the front area of the crankshaft to the rear, reducing the distance between the engine’s front cover and its crankshaft by 7mm. Together, these changes have resulted in an engine that is 29mm shorter from the front of the engine to the rear of the left cylinder head, which has in turn enabled engineers to move the engine and rider position forward. Hugely impactful, this shift increases frontend weight bias and promotes even sportier handling on the 2018 Honda Gold Wing.
A newly adopted Unicam valve train, a design that has been proven in Honda’s CRF450R, uses a finger-follower rocker-arm system on the intake side and roller rocker-arm system on the exhaust side. Doubly beneficial, this design enabled removal of the valve-lifter-support structure from the previous-generation engine, resulting in a weight savings while also enabling the engine to be more compact. The roller rockerarm system on the exhaust side also reduces friction, contributing to improved fuel efficiency. A new molybdenum coating on the piston skirts has the same positive effects.
Thanks to the improvement in aerodynamic efficiency and a reduction in weight, it was possible to reduce the fuel tank capacity by 1.1 gallons (4 liters), to 5.5 gallons total fuel capacity (21 liters) for improved handling performance while maintaining the same great range as before. In testing, total fuel economy was up 20 percent. Furthermore, the change to a smaller fuel tank results in improved mass centralization and less weight. Of any Gold Wing, this latest version takes the biggest steps toward bringing the mass toward the center of the motorcycle for improved agility and handling.
The all-new engine uses four valves per cylinder in pent-roof-type combustion chambers for improved combustion efficiency, but still weighs 13.7 lbs. less (6.2 kg) than the outgoing powerplant, when equipped with Honda’s six-speed manual transmission. Intake valves measure 27mm, whereas exhaust valves are 24mm. For added weight reduction, cylinder sleeves are now made from aluminum, the camshaft is manufactured from FCD600M, a lightweight, high-strength material, and water-cooling routes have been simplified and lightened by repositioning the thermostat. All this helps to create a package that is significantly more compact and performance-minded on the road, with a greatly improved power-to-weight ratio.
Intake
Intake efficiency has been improved for added responsiveness and torque, while the intake system itself has been made lighter: The number of throttle bodies has been reduced from two to one, the thickness of the intake manifold has been reduced from 3.5mm to 3mm, and the inner diameters of the intake manifold have been revised as well. For efficiency purposes, intake-manifold volume has been reduced by 10 percent, and the intake ducts have been reimagined, with the left duct placed forward and the right duct facing rearward. This design, which creates a swirl effect on the incoming air, also results in a more effective use of the entire air filter. The intake duct shape and size have been optimized for improved response and torque at initial throttle openings.
Exhaust
To create an exhaust sound worthy of the new Gold Wing, a new structure was designed for the sequence leading from the muffler to the exhaust pipe, ensuring an appropriate sound quality. The No. 2 and No. 3 exhaust pipes (left to right from the rider’s view) have a 20-percent smaller diameter.
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