1967, Übersicht

This will be, for the time being, Honda's last year in Grand Prix racing. They pull out of 50 and 125 cc racing at the end of 1966 and, at the end of the 1967 season, Honda withdraws from the other three classes. They have achieved what they set out to do: from a totally obscure and unknown company at the start of 1960, they have become the biggest and best known motorcycle manufacturer in the world. Yet, the decision comes unexpected – Hailwood and Bryans have already signed their contracts for 1968. Moreover, there are rumours about new, exciting racers – a 50 cc triple, a 125 cc six cylinder and a V8 for the 250 cc class.

Suzuki also stops at the end of the season, and Yamaha follows one year later.

In the 250 cc there is a fierce, ongoing battle between Read and Ivy on the Yamaha fours and Hailwood and Bryans on the Honda sixes, a battle that's only decided in the last race of the season. The Yamahas have been improved and are lower and more powerful, they have now some 5 horses more than the Honda six. This is compensated by the fabulous riding of Hailwood, but on very fast circuits, such as Francorchamps and Monza, the Yamahas have the advantage because of their superior speed.
Hailwood and Read both end up with the same number of points, but Hailwood wins the title, for he has 5 wins against Read's four. Ivy ends up third. The Manufacturers' title goes to Honda, followed by Yamaha, MZ and Bultaco.

During 1966, Mike had been complaining about the roadholding and handling of the fours, and Honda decide to enlarge the 250 cc six, about which Hailwood had no complaints, to give him a new weapon for the 350 cc class. With more power than the four and nearly 20 kg less weight, the combination Hailwood and Honda six is so superior, that Hailwood wins the title by winning the first five races, and then hands the bike over to Ralph Bryans, who gathers enough points during the rest of the season to end up third in the world championship. Agostini is second with the MV. The manufacturers' title goes to Honda, ahead of MV Agusta, MZ, Aermacchi and Benelli.

The battle in the 500 cc class is between Hailwood and Giacomo Agostini with the MV. Hailwood complains, that he has to fight two opponents: Ago and his Honda, which, although it has a superb engine, has very bad road holding. At the end of the season, both riders have the same number of points and both have 5 wins; Hailwood has two second placings, but Agostini has three seconds and so becomes world champion, with Hailwood second and John Hartle (Matchless) third.

 350 cc RC174

The RC174 is the enlarged version of the RC166, the total cylinder capacity of 297.06 cc is achieved by retaining the bore of 41 mm and increasing the stroke to 37.5 mm. Compression ratio is 10.6 : 1. Inlet valve diameter is 16.5 mm, exhaust valve 14 mm. Carburettor diameter is 22 mm. Power output is 67 bhp at 17,000 rpm, maximum torque is 2.8 kgm at 16,000 rpm.

Image above shows Mike at the Isle of Man TT with the RC174.

 500 cc RC181

T1967 500cc RC181 Hondahe RC181 this year no longer has the bolted-on sub-frame, and the megaphones have lost the reverse cones. Capacity is increased to 499.7 cc by enlarging the bore to 57.5 mm; the stroke remains the same at 48 mm. Power output is now nearly 90 bhp at 12,000 rpm, maximum torque is 5.23 kgm at 10,000 rpm.

One of the experiments to improve handling is mounting the front wheel in excenters, so the trail could be altered – it didn't bring much. 

1967 500cc RC181 HondaDry weight is 151 kg, top speed is given as more than 260 km/h.

aus:

Honda's Four Stroke Race History 1954-1981
by Joep Kortekaas