Short strokes

[Alexlib]

Question
Which engine number was the first short stroke, I read that it was introduced in 1961. Is this correct?
How many were made?

[Reynard24]

If one assumes that Fred Neill’s singles manual is correct, then the first short stroke road 350 engine should be 41575 and was introduced for the 1962 model year, so from September 1961. These were the 74x81 “ultra short strokes” of 1962 and 63. The ‘64 on (Sept 1963 production start) 72x85.5 short stroke engines don’t seem to have a start number, perhaps John Tinley can throw more light on the subject?

[Alexlib]

Thanks for the info, I hadn’t realised they had redesigned the stroke twice, I wonder why?

[Reynard24]

Probably due to economy of scale, by ‘63 AMC were in financial trouble so when the road 500 short strokes (86x85.5) were introduced in’64 it probably made sense to use the same crank (85.5mm throw) and oil pump (Norton gear type) in both.
I’ve ridden both and would have to say the 74x81 earlier type is more punchy than the later bikes, I also prefer the AMC forks and wheels too.

[Alexlib]

Using a common crank makes sense.
I do find the road holder forks stiff, mine has been converted to 500 so plenty of punch.