Hi Mar
I like your post. As a long time Trident owner I am biased towards the bikes but what you say is correct regarding the seperate push rod tubes, rocker boxes and complex crankcase. To me they always feel like a prototype awaiting final improvements.
Im not familiar with BSA twins but if the performance figures for the A65 are correct it would of made a hell of a bike with an overall more modern appearance that might have been easier to live with.
As it is, I have had my trident bored out to 830 cc with spitfire cams and three into one which certainly improves it’s lower end and mid range power.
Please note, this post is not intended to be a comparison between Nortons and Tridents, just an interesting observation.
The 74 Mk 2 is a lovely bike to ride but to me it does seem a little breathless above 5000 rpm, not that I want to ‘ring it’s neck with high revs
Al
hi Mark,The Kawasaki was light, as was the Commando.
In 1970 BSA were testing what would be the works 750 3 I expect against the power graph of an A65 twin with A10 crank and almost matching it. The twin had 78hp @ 7,000 at the crank. They were revving the 3 to 9,500 and still shy. And even a hot 650 A65 was beating it to 5,500rpm. The biking world would have been different if only the 3 cylinders were based on the A65. Thunderbolts have 27mm ports like the triple except they flow 108cfm each. If they used the Spitfire cam, same bore, short stroke for a 750cc, pushrods inside, with the oil, the motorcycling world would have been a different place. On the mildest hp calculator that flow would enable 77hp.
With A65 stroke and '71 porting for a 981 triple 87hp and massive torque would have decimated the Z1 with technology they had, and those heads can be made to flow enough for that to be around 120hp in a race motor with fierce mid range. Yet they chose a 500 Triumph base with ports crowded with head studs, as if BSAs development didn't exist. And no less than 4 external pushrod tubes and separate rocker boxes to leak oil which were so unnecessary, as was all the complex crank cases with the expense and time intensive assembly.
And the head of the BSA/Triumph company was thinking they needed OHC motors to catch the modern Japanese advances.
I like your post. As a long time Trident owner I am biased towards the bikes but what you say is correct regarding the seperate push rod tubes, rocker boxes and complex crankcase. To me they always feel like a prototype awaiting final improvements.
Im not familiar with BSA twins but if the performance figures for the A65 are correct it would of made a hell of a bike with an overall more modern appearance that might have been easier to live with.
As it is, I have had my trident bored out to 830 cc with spitfire cams and three into one which certainly improves it’s lower end and mid range power.
Please note, this post is not intended to be a comparison between Nortons and Tridents, just an interesting observation.
The 74 Mk 2 is a lovely bike to ride but to me it does seem a little breathless above 5000 rpm, not that I want to ‘ring it’s neck with high revs
Al