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John Olsen13/02/2018 06:04:32
851 forum posts
85 photos

Do you mean 90 or 180? Either has the disadvantage of uneven firing intervals. The 180 balances the reciprocating forces, except that they are not in line so it introduces a rocking couple in a way that a motorcycle frame is not well placed to resist. Honda used both 180 and 360 degree cranks on parallel twins. The 150, 160 and I think 175 twins had the 360 crank, while the bigger ones had the 180, which gave the 350 twin a particular beat to the exhaust note.

But back on the Triumph twins, I think the smaller incarnations were nicer...the 350 and the Daytona 500. The 650's were OK as long as they were not hotted up too far, but as they went on and tried to get more and more power out of the same design they got less and less pleasant.

I think there was quite a lot of "Not invented here" about BSA Triumph in their later years. They wouldn't do anything that the Japanese had done which pretty much locked them out of improving their bikes at all.

John

John MC13/02/2018 08:01:03
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62 forum posts
6 photos

"Phil Irving tried to get the British vertical twin manufacturers to change to 90 degree cranks many years earlier and got laughed out the factory gates. It was a long-standing and enduring prejudice I guess."

Yes, Phil Irving (one of my engineering hero's) was keen on the 90 degree crankpin spacing for a parallel twin, an attempt to reduce vibration by utilising the best of both arrangements? Its now accepted that Irving made one of his very, very few mistakes in suggesting 90 degrees, as has already been said, 76 degrees, or near would be better.

As for prejudice and "not designed here syndrome", plenty of that, look what happened to the BSA/Triumphs last gasp attempt to stay in business, the Bandit..........

John

Hopper13/02/2018 08:09:20
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2264 forum posts
32 photos

I think some of the current Triumphs have a 90 degree crank, ie a 270 degree as it is called. Have not seen a 76 degree in use. Perhaps some of the Japanese v-twins, which I don't mess around with?

thaiguzzi13/02/2018 08:15:41
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320 forum posts
86 photos

Yabbut, they didn't think like that in '62-63 in Britain.

If anything, they probably would have gone 180. Nowadays the 270 or 90 degree crank is the new "in" thing. How to get a v twin in a parallel degree package...

Posted by ronan walsh on 12/02/2018 12:18:51:
Posted by thaiguzzi on 12/02/2018 03:29:36:

Concur. One of THE greatest looking motorcycle engines. However, day to day riding, compared to a 650, too revvy and a bit gutless.

Now if they'd only made a 650-750 version of that top end externally...

By the way, I've owned and worked on Triumph twins for 35 years +. I had my own Meriden big twin shop in the UK for 15 years. Became rather well known by the time I sold up.

Posted by ronan walsh on 11/02/2018 15:47:18:

That all alloy engine was one of the best looking motorcycle engines ever made. I have the makings of a triton here, but have to finish rebuilding my old a10 golden flash first.

The time for meriden to completely revamp the engines was when they switched from pre-unit to unit construction. They stuck with the same cylinder spacing and 360 degree crankshaft. Instead of going wider and allowing larger bores, and they should have went with a 76, or 90 degree crank, it would have been easy to enlarge the engine and still have it vibrate less.

thaiguzzi13/02/2018 08:22:33
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320 forum posts
86 photos

Don't forget, mid 60's onwards, money was getting ever tighter, especially with the nutters in the BSA boardroom, and the way what money was there, was spent frivously. Bernard Docker anyone? Slumberglade Hall?

The downfall of Meriden Triumph, began in earnest when BSA started taking ever more interest in the concern, mid 60's onwards, because it out produced Small Heath, with less employees, and a more saleable product. (BSA brought Triumph in late 50's?).

Plenty of excellent books out there - read them and weep.

From a man who has more than one Triumph tattoo.....

ronan walsh13/02/2018 13:08:51
371 forum posts
29 photos

I am building a 90 degree triumph engine at the moment. It can be done using the stronger norton commando crankshaft, which i am sure you know, has two throws bolted to a central flywheel. A relatively simple task of making a new flywheel, turning the timing side mainshaft to triumph dimensions.

Camshafts are available for the rephased crank, as are conrods to suit the norton crank in the triumph cases.

With a big bore kit the capacity ends up a little over 800cc. A toolmaker chap i know in Australia has done several of these conversions, and reports that even without dynamic balancing, the 90 degree engine is noticeably smoother than the smaller capacity 360 degree engine.

So Phil Irving and his theories were vindicated, and as Hinkley triumph twins are this configuration now, it appears to be the way to go.

ronan walsh13/02/2018 13:12:01
371 forum posts
29 photos
Posted by thaiguzzi on 13/02/2018 08:22:33:

Don't forget, mid 60's onwards, money was getting ever tighter, especially with the nutters in the BSA boardroom, and the way what money was there, was spent frivously. Bernard Docker anyone? Slumberglade Hall?

The downfall of Meriden Triumph, began in earnest when BSA started taking ever more interest in the concern, mid 60's onwards, because it out produced Small Heath, with less employees, and a more saleable product. (BSA brought Triumph in late 50's?).

Plenty of excellent books out there - read them and weep.

From a man who has more than one Triumph tattoo.....

I was reading about the infamous Nora the other day, presenting the bsa/triumph board with outrageous bills for her latest fur coats and other outfits. She reckoned that she was justified, because she appeared on show stands bedecked in her finery, i can just imagine the faces of the ton-up boys standing there looking at her draped over a bike.

Not good.

Mike Poole13/02/2018 14:12:07
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1112 forum posts
31 photos

I don't think the engineers at Triumph/BSA were short of ideas on how to build a modern engine with modern machinery but the money to buy it just wasn't there. I believe the Trident/Rocket3 were intended to be built like Japanese engines but that would have meant retooling so it had to be built like the twins. John Bloor showed what could be achieved with a clean sheet and sufficient money. The workers realised they had been let down by bad management but learned a hard lesson that the real world wasn't ready for a workers coop.

Mike

Edited By Mike Poole on 13/02/2018 14:13:16

ronan walsh13/02/2018 16:31:58
371 forum posts
29 photos
Posted by Mike Poole on 13/02/2018 14:12:07:

I don't think the engineers at Triumph/BSA were short of ideas on how to build a modern engine with modern machinery but the money to buy it just wasn't there. I believe the Trident/Rocket3 were intended to be built like Japanese engines but that would have meant retooling so it had to be built like the twins. John Bloor showed what could be achieved with a clean sheet and sufficient money. The workers realised they had been let down by bad management but learned a hard lesson that the real world wasn't ready for a workers coop.

Mike

Edited By Mike Poole on 13/02/2018 14:13:16

Yes, bad management and greedy investors, never any profits set aside for reinvestment. Some of the machinery sold off during the closure of the Meriden factory in the early 1980's, was pre-war manufactured ! Unthinkable in this day and age, i believe in the new triumph factory, all the machinery is replaced every three years, regardless of condition.

JimmieS13/02/2018 16:45:24
201 forum posts
2 photos

One of the so called 'cottage industries' for the motorcycle restorers

.**LINK**

ronan walsh13/02/2018 16:51:22
371 forum posts
29 photos
Posted by JimmieS on 13/02/2018 16:45:24:

One of the so called 'cottage industries' for the motorcycle restorers

.**LINK**

I wondered whatever happened to him. He had a place in Yorkshire and was big into making uprated parts for Triumph tiger cubs, a favourite with the pre 65 trials mob. Glad its working out well for him.

thaiguzzi14/02/2018 08:49:56
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320 forum posts
86 photos

Horizontal multi split crankcases = 1 gasket interface.

Vertically split Triumph trident/BSA Rocket III c/cases = 7 gasket interfaces.

Go figure....

Posted by Mike Poole on 13/02/2018 14:12:07:

I don't think the engineers at Triumph/BSA were short of ideas on how to build a modern engine with modern machinery but the money to buy it just wasn't there. I believe the Trident/Rocket3 were intended to be built like Japanese engines but that would have meant retooling so it had to be built like the twins. John Bloor showed what could be achieved with a clean sheet and sufficient money. The workers realised they had been let down by bad management but learned a hard lesson that the real world wasn't ready for a workers coop.

Mike

Edited By Mike Poole on 13/02/2018 14:13:16

Bob Rodgerson14/02/2018 10:22:40
524 forum posts
163 photos

I agree with Mike,

I have on the bench at the moment, a BSA Fury Engine which came out of the research department at Umberslade Hall I am building the engine up from part machined castings and a crankshaft/conrod assembly to, hopefully a working engine when it is finished. It is a long term project that is nearing completion with both crank case halves machined and the lower valve drive train and oil pump drives sorted. The cylinder head will be the next thing to be machined to accept the camshafts and once this is done I will machine the Hemispherical shape for each cylinder before it goes off to a cylinder head specialist to have seats and guides fitted.

The engine is very Honda like being a DOHC twin with the camshafts running directly in the Alloy Cylinder head rather than bearing bushes or needle rollers. Had more money had been available to develop it and improve reliability it could well have become the machine to beat it's Japanese rivals. However I do think that by the early 70's a 350cc engine was the wrong size to go for, people, then were wanting bigger OHC engined bikes and a 750 version would probably have been the right size to go for.

ronan walsh14/02/2018 14:15:09
371 forum posts
29 photos
Posted by Bob Rodgerson on 14/02/2018 10:22:40:

I agree with Mike,

I have on the bench at the moment, a BSA Fury Engine which came out of the research department at Umberslade Hall I am building the engine up from part machined castings and a crankshaft/conrod assembly to, hopefully a working engine when it is finished. It is a long term project that is nearing completion with both crank case halves machined and the lower valve drive train and oil pump drives sorted. The cylinder head will be the next thing to be machined to accept the camshafts and once this is done I will machine the Hemispherical shape for each cylinder before it goes off to a cylinder head specialist to have seats and guides fitted.

The engine is very Honda like being a DOHC twin with the camshafts running directly in the Alloy Cylinder head rather than bearing bushes or needle rollers. Had more money had been available to develop it and improve reliability it could well have become the machine to beat it's Japanese rivals. However I do think that by the early 70's a 350cc engine was the wrong size to go for, people, then were wanting bigger OHC engined bikes and a 750 version would probably have been the right size to go for.

An interesting project Bob. Love to see pictures of that engine. What i did hear about the fury/bandit, being an Edward Turner design, its basically flimsy, and still suffers the old problems, like vertically split crankcases, which are more prone to oil leakage. The man to sort out triumph would have been Doug Hele, but sadly again he got free reign, the money was drying up fast as the japanese took over the market.

Bob Rodgerson15/02/2018 09:58:30
524 forum posts
163 photos

Hi Ronan,

Vertically split crank cases were a natural and easy way to make single cylinder engines. When the parallel twin without centre bearing came about it still remained the way to go, there were a few odd exceptions such as the AJS and Matchless twins which had a centre bearing fitted in a split housing that could be inserted and bolted up when the crankshaft was inserted into the cases.

However once multi Cylinder engines became the norm, there was little choice but to split the cases horizontally, car engines have been made this way for years or with underhung crankshafts and a sump cover to hold the oil.

The adoption of multi cylinder engines for motorcycles really took off in the early seventies at a time when most of the British twins and singles were reaching the end of their design and possibly their general working lives. As a result there were huge quantities of tatty, ill maintained bikes on the road a lot of which will have been, in the past, attacked with screw drivers and chisels to open the cases during major maintenance and I believe it is this that gives the vertically split case it's bad name.

If the faces of the joint are perfectly flat and unmarked they will seal, my BSA A-10 doesn't leak despite it being over 50 years old.

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