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NickL #825147 09/29/20 9:27 am
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Originally Posted by NickL
The one i liked was the Riley 9 engine twin high cam setup '30s lovely engine and very quiet.

Comparing a Riley 9 engine to a Triumph twin might surprise a person.


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Originally Posted by Rohan
Oddly though, IOE designs mostly predate sidevalves.

Many early engines had an automatic (atmospheric pressure operated) inlet valve, in the overhead position.

Fitting a pushrod and a rocker to it, to make it a mechanically opened valve, was a fairly simple development that landed you with an IoE engine.


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Originally Posted by triton thrasher
Many early engines had an automatic (atmospheric pressure operated) inlet valve, in the overhead position.
Fitting a pushrod and a rocker to it, to make it a mechanically opened valve, was a fairly simple development that landed you with an IoE engine.

Yes, its a fairly logical progression.
But sidevalves were thought of quite early one, mechanically operated even, but didn't really catch on until a decade or 2 later

I didn't know that about Landrover engines
Can spot it a mile away when you see the cylinder head.
Rolls Royces ditto

https://www.defendersource.com/attachments/imageuploadedbytapatalk1418401489-921490-jpg.108533/
https://www.flyingspares.com/shop/m...525d08d6e5fb8d27136e95/r/e/re7753u-1.jpg
Watercooling negates a lot of the disadvantages of a hot exhaust valve located low down in the engine.

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Originally Posted by reverb
...is due to the head that Triumphs have the advance more than the other British motorcycles?
HD s sportsters have the same advance? (due to the similarity of the head chambers)

Thanks
Yes, engines with deep hemi chambers generally need more ignition timing.
Harley produced the 45 side valve till 1973.
In the USA, the 1949 Olds and Cadillac OHV V8 wedge head engines started the death of slogging side valve engines. Buick had a patent for their OHV engine in 1904. It had two pushrods and valve springs. Chevy always had OHV engines


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Rohan #825156 09/29/20 12:33 pm
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Originally Posted by Rohan
Originally Posted by triton thrasher
Many early engines had an automatic (atmospheric pressure operated) inlet valve, in the overhead position.
Fitting a pushrod and a rocker to it, to make it a mechanically opened valve, was a fairly simple development that landed you with an IoE engine.

Yes, its a fairly logical progression.
But sidevalves were thought of quite early one, mechanically operated even, but didn't really catch on until a decade or 2 later

I didn't know that about Landrover engines
Can spot it a mile away when you see the cylinder head.
Rolls Royces ditto

https://www.defendersource.com/attachments/imageuploadedbytapatalk1418401489-921490-jpg.108533/
https://www.flyingspares.com/shop/m...525d08d6e5fb8d27136e95/r/e/re7753u-1.jpg
Watercooling negates a lot of the disadvantages of a hot exhaust valve located low down in the engine.

My work had a six-cylinder long wheelbase petrol Land Rover. It did eight miles per Imperial gallon.


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that late Crocker motor had vertical valves with a flat top chamber and flat top pistons. The 883 sportster had hemi chamber and could be slapped on top of 1100 cylinder giving a squish band. Buell must've been doing something similar.

back to OP, the best design would have to be the last one to fall = Triumph
but then Triumph is back, love it or hate it
Norton came back , took the money and ran
BSA is yet to be dug up

Id say the best design by far was the Royal Enfield Bullet

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Going back to original question I have to correct my first post, the best head design BSA produced in early fifties in a Sunbeam engine - vertical valves and a squish combustion chamber a la Crocker in a OHC aluminum engine design with a cylinder being part of an upper case and engine cases horizontally cut.
Reading Roland Pike's BSA memoirs I can't believe they didn't work to develop this engine having it in the same company ( Reddith )

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Originally Posted by triton thrasher
Originally Posted by NickL
The one i liked was the Riley 9 engine twin high cam setup '30s lovely engine and very quiet.

Comparing a Riley 9 engine to a Triumph twin might surprise a person.

Edward Turner drove a Riley 9 (as did Reginald Mitchell BTW), and I remember reading an article in Motorcycle Sport mag that said his Speed Twin design could well have been based on the Riley design. I have to say I'm biased as I drive a post war Riley 1½ (not to be confused with the later badge-engineered 1.5) and also have a '65 TR6SS! As has been said, a very advanced design that was still pretty good in the 1960s, which is why in the mid Sixties the thirty year old design still helped to make the Bonnie one of the world's fastest production bikes.

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Hi, There’s a saying good minds think alike. It was a time of discovery & innovation. Yet product had to be affordable to build & buy. Turner & others had this formula worked out well. The introduction of high octane fuel allowed huge increases in effective compression ratio & power.
A very important part of success in sales is a good dealer network. Triumph & Harley, Honda understood this well.
Indian, BSA, Norton were lacking here, especially in the 60s.
The old timers when I worked at Harley dealer to a man felt Indians were better. But dealers were not so good overall. Indian owners got feed up with dealer issues & moved to Harleys.
My local BSA dealer was a greasy hole in the wall. Terrible service too. Local Norton dealer was in lawnmower shop! Lawnmower mechanics struggled best they could.
Everyone at Trumph/BSA wanted to innovate except the top brass. The results is history.


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