Britbike forum Forums British Motorcycle specific Brands Bsa bulletin board The what if A65 67hp challenge.

And if BSA had actually done this to every production model they would have had to charge how much for each bike? They had enough trouble selling them at the price they charged.
Looks like a fun project though.

Costs just as much to make something properly as it does it make something incorrect.

Then why didn't BSA do it properly?
It always seemed to me that the A65 was like the Combat Norton,a desperate attempt to wring modern performance from an antique design. At least Norton improved the bearings after that fiasco. BSA didn't even bother to update their oil system.

Hopwood in his book states the attitude of the Managing Director that BSA and Triumph machinery must be equally prepared so it was unlikely they would have made the improvement to the A65. When Dan Macias visited the Triumph factory he saw they were finishing the Triumph twin ports on a drill press. Doug Hele told him not to mention it because the operator had been doing it that way for many years.
By May 1971 BSA was looking at a loss of 1m GBP so was hardly in the position to make any changes to the design.
I think the A70 was the only one with steel capped rods but not sure.
The 350 was a disaster because it was "designed" by Turner (who checked valve springs by stepping on them with his heel). Two broken crankshafts and one valve gear failure in 1500 miles. The cutaway picture of the engine shows the characteristic Turner sharp angle between the port and valve. Also, by '71 you think they would have figured out it was a bad idea to put the output sprocket between the clutch and gearbox.

Then why didn't BSA do it properly?
It always seemed to me that the A65 was like the Combat Norton,a desperate attempt to wring modern performance from an antique design. At least Norton improved the bearings after that fiasco. BSA didn't even bother to update their oil system.

It's not particularly hard to do the ports by hand. BSA could have done the ports at least to how they were designed rather than short cutting at the factory, it may have been saving them a little money and keep the A65 on parity with the Triumph twin which they also owned. In 1970 they knew the difference between the heads but didn't rectify the production, they could have had 8 more hp in 1971. In their day these bikes were among the fastest most powerful on the road, but they were about to be displaced, or by 1971 they were being displaced by the 750s and the power bikes from Japan.

It was hardly a time to throw away easy hp in what was a full-scale hp race. You can see this when the mighty Z1 Kawasaki turned up, it was called the King. It was developed as a 750 but Honda released the CB750 4, getting the jump. Kawasaki held off releasing their bike till they increased the displacement to 903cc the reason they did that was to sell bikes, they understood the power of power. Honda claimed 67hp Kawasaki trounced it with 82hp and 54.2ftlb, though it was heavy at 542lb. For perspective my 883cc A65 weighs around 360lb and produces 97hp and 71ftlb it also has a very wide power spread. It uses a bigger version of the oval port above, so I'm interested to see how that translates onto an otherwise stock engine.

BSA already knew how to fix all the problems with the A65, roller mains both sides would have reversed market resistance, 71 or earlier they had excellent steel capped rods, high volume oil pumps and they had the A70 showing great potential. But they sank money and effort into things like the Ariel 3. And also the 350s that were a good idea though eventually scrapped because of a shot to the foot.

The 350 was a missed opportunity, they could not get good power from it because the head design was poor, DH had made an error, easy to rectify with a new casting, but management told him no. So 34hp was the best they could ever get. The 350 Honda was already in the market with similar power, the BSA 350 could and should have made 45+hp, and it would have been a winner, it could then be more expensive than the Honda because it gave more, it had the advantage with a state of the art frame and running gear already. A company like Kawasaki would have made sure they had what they needed to get the power necessary. So rather than spend massive effort and money fruitlessly down these paths, BSA could have done three things, fixed the A65 engine completely, and at the same time, because its basically the same thing, developed the A70And the third, built at least a limited number of Rob North style Rocket threes, the frames were state of the art and exotic, cheaper to manufacture than the std frames. The threes also work extremely well at 850cc if they wanted to respond to the Z1 and Ducati's SS750 when they came along.

A massive slice of their market was the 'states.
It would have been more of a benefit to make the a65 more reliable and long lived than to uprate it's horsepower.
The average bloke who bought a bike wasn'r racing it, he was riding it once a week and poorly maintaining it.
His mates with triumphs could get away with not changing oil etc so he would do the same...........the beezer went bang.
They should have shut down in 1963 and moved production to the far east, that way they would have had local access to
a massive market and government funded factories/development. Competing with japan's zero interest rate for business at
that time was impossible, they could product dump anywhere in the western world with government backing, and they did.
Beezer was nothing compared to the yankee electronics industry they devastated.
The management at beezer were just selling it all off and getting out, they didn't want to make motorbikes, they wanted to
make money. Pi$$ing about modifying cylinder heads on an out of date engine that's been in production for 10+ years
is the sort of thing that makes firms go broke.
I understand the nostalgia and i love the old crates as well, but politics and economics etc. get in the way.

Hopwood in his book states the attitude of the Managing Director that BSA and Triumph machinery must be equally prepared so it was unlikely they would have made the improvement to the A65. When Dan Macias visited the Triumph factory he saw they were finishing the Triumph twin ports on a drill press. Doug Hele told him not to mention it because the operator had been doing it that way for many years.
By May 1971 BSA was looking at a loss of 1m GBP so was hardly in the position to make any changes to the design.
I think the A70 was the only one with steel capped rods but not sure.
The 350 was a disaster because it was "designed" by Turner (who checked valve springs by stepping on them with his heel). Two broken crankshafts and one valve gear failure in 1500 miles. The cutaway picture of the engine shows the characteristic Turner sharp angle between the port and valve. Also, by '71 you think they would have figured out it was a bad idea to put the output sprocket between the clutch and gearbox.

Costs just as much to make something properly as it does it make something incorrect.

Be interested to know what the difference in the blueprint head and the other heads. theres 2 casting/part numbers for the OIF 2 carbs heads, a few suttle differences between them, but never measured the ports..... too late now as both of them are modified.

I think the non-return valve thing is often the pumps leaking at the joint. Dave's comment is interesting heads being ported with a drill press and confirming that an A65 with more hp than a T120 was not wanted let alone one to out perform the flagship threes.

The thing is, a well made hemi head motor can be a great thing. Chrysler still make brilliant Hemi V8s, they have a different power delivery to multivalve V8s, enormous bottom end midrange and then they scream in a very Don Garlits sort of way, Toyota make a multivalve V8 petrol it's smaller than the Hemis but very bland in comparison to the massively more powerful psycho nature of the hemi. The base version is 470hp Toyota's multivalve feels like 180hp.