Vintage motorbike

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Phil Whitley on 08/10/2014 18:07:40:

Hi all, Sorry Mr Gilligan the Ariel Arrow was a 180 deg twin, not a parralell.

PS, so no one knows where the Queen keeps her chickens then, I am surprised at you all! It is relevant to the original post.

.

Mr Whitley [or may I call you Phil ?] … I suggest you do some revision before the Geometry Test … The Arrow engine was a Parallel Twin, with a 180° Crank

As for the chickens … Yes it was obvious that HRH keeps them in the Royal 'en Field … but I didn't realise that you needed written answers. [just a wry smile as I read it]

MichaelG.

[ronan walshParticipant @ronanwalsh98054]

Triples ehh ? I have the old lump below adoring one of my tool chests. The plan is to put it into a featherbed frame i have, when money and space allow. The twins were good up until they hit about 30 bhp, edward turner thought it a bad idea to even take them out to 650cc's. If you are lucky enough to be able to try an early thunderbird or golden flash, and then sample a late 60's 650 twin , the difference should be extremely noticable. I have a mid 50's BSA a10 golden flash which were built in a low state of tune, and its a very pleasant machine, where as my late 60's triumph 500 is in a much higher state of tune and is a bit tiresome to ride far.

The british bike industry went from one of the most innovative and inventive pre-war to knocking out the usual same old singles and twins post war.

[ronan walshParticipant @ronanwalsh98054]

Posted by richard allen 6 on 08/10/2014 07:40:11:

Posted by ronan walsh on 08/10/2014 00:42:58:

I Have we forgotten the Hesketh?

Actually yes i have, but seeing as they were so scarce and expensive thats an easy thing to do !

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Hopper on 08/10/2014 13:02:20:

I dont think the v-twins were any smoother than the vertical twins.

.

Without using additional balance shafts, etc. I think it's only the Ducati layout that can give a fully balanced twin cylinder 4-Stroke [pedants may wish to debate whether this a V or an L but I don't really care].

Happy to be corrected on the uniqueness of the Ducati, but I don't think anyone else has used 90° in a motorcycle.

MichaelG.

[Neil WyattModerator @neilwyatt]

My mum used to say an Ariel Square Four was the best bike she ever rode on, which upset my Dad as it was about the only bike of the era he hadn't owned!

Neil

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Neil Wyatt on 08/10/2014 18:30:27:

My mum used to say an Ariel Square Four was the best bike she ever rode on, which upset my Dad as it was about the only bike of the era he hadn't owned!

.

Brilliant

MichaelG.

[OuBallieParticipant @ouballie]

Posted by Neil Wyatt on 08/10/2014 17:25:57:

snip/

A tax disc holder. You youngsters wouldn't remember those

/snip

You are my best friend with that remark.

Mote serious though . . . .

How the heck do you insert smileys at the end of a sentence?

Every time I try, they end up top left of the post, so I have to CUT then Paste.

Geoff – Pick her indoors up late tonight, from the pub where her ex-boss is having a farewell do.

[Neil WyattModerator @neilwyatt]

> How the heck do you insert smileys at the end of a sentence?

Practice

Neil

[Mike PooleParticipant @mikepoole82104]

Michael, you have forgotten the Moto Guzzi, 90° but transverse.

If I had a spare Trident lump is would have to go in a Rob North rolling chassis, would need deep pockets to see that happen though, when I ran my T150V it kept me poor and Norman Hyde rich, I used to be very good at supporting pub landlords and Triumph parts suppliers. My Hinkley Trident just needs petrol, chains and tyres.

Mike

Edited By Michael Poole on 08/10/2014 19:19:49

[John BromleyParticipant @johnbromley78794]

Both Honda and Suzuki have built many 90 degree v twins. I have a Suzuki Vstrom 650 at present, had a Vstrom 1000 previously. Both great engines.

John

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Michael Poole on 08/10/2014 19:07:10:

Michael, you have forgotten the Moto Guzzi, 90° but transverse.

.

Mike … Yes of course

and a quick check on Wikipedia provides a useful list.

MichaelG.

.

Edit: … John; you deserve my blushes too !!

Edited By Michael Gilligan on 08/10/2014 19:41:38

[ronan walshParticipant @ronanwalsh98054]

Triumph sent an engine to one of the engineering departments of GEC to see if their experts could tame the vibration, they could and did make a triumph 650 twin engine that you could balance a coin on its edge while it ran. Sadly the engineering was too expensive for triumph to encorporate into the production machines.

A great insight into all things british bike is hughie hancox's excellent book "Tales of triumph and the meriden factory"

[Mike PooleParticipant @mikepoole82104]

Michael, that is a long list! I am surprised at the small capacity of some of them.

Mike

[Nick_GParticipant @nick_g]

.

This next post is unashamedly picture heavy.!

I feel that will be OK due to the interest in this post so far.

A couple of years ago I went to pick the car up from a mechanic we used. Barry had a lifelong tradition of building, maintaining, preparing, driving / riding both race cars and bikes. – He had just finished a TriGreeves and it was in the yard. I later life he handed the driving and riding to younger blades.

'Luckily'.!!!!!!!! I had a camera with me and took a few images of his latest restoration. —— I say Luckily as Barry sadly died of heart failure 2 days later. (that's Barry in the blue overalls)

I feel that due to many of the parts in this project having to be made again from scratch and the fairly modest size of them, plus the general interest (by some) in motorcycles of that era that this post is valid on this forum. (Moderators, please correct me if I am wrong)

 

Nick

Edited By Nick_G on 08/10/2014 20:51:20

[Michael GilliganParticipant @michaelgilligan61133]

A great post, Nick

Took me back instantly to the mid 1970s , when a chap at work had a 350 Tri-Greeves

MichaelG.

[Tony Pratt 1Participant @tonypratt1]

Posted by Michael Gilligan on 08/10/2014 21:05:47:

A great post, Nick

Took me back instantly to the mid 1970s , when a chap at work had a 350 Tri-Greeves

MichaelG.

Hi Michael,

Couple of pictures from 1972, 3 months later I hit a car at 60, wrote the bike & car off, suffered life changing injuries but the full face helmet I was wearing saved my life.

Tony

[Michael GilliganParticipant @michaelgilligan61133]

Tony,

Glad you survived to show us the pics of that proud young man and his bike.

I remember some time around then, Bell ran a rather persuasive advert … something along the lines of: If you have a Ten Dollar head, buy a Ten Dollar helmet.

… a thought that has stayed with me.

MichaelG.

[MuzzerParticipant @muzzer]

I only vaguely recall from my student days how to calculate the out of balance forces on various engine configurations and it's something I chose not to revisit although it is quite interesting. The closest twin to having perfect primary balance is the boxer (opposed pistons ) with 2 crank pins. Almost any vee is going to shake like a pig unless you use balancer shafts because the primary balance is always going to be poor in both axes. The vertical twin is a pig too, whether you have the pistons going up and down together or 180 degrees apart.

Quite well written article in Wikipedia compares various engines – including a fairly lengthy section about steam engines towards the bottom.

Murray

[John Stevenson 1Participant @johnstevenson1]

Vic Willoughby who used to write for one of the motor cycle papers and also wrote some books had a very good insight on balancing engines.

I think secretly it was his pet subject as he always managed to work it into many of his articles.

 

I'll leave it to our resident Google Child to come up with all the links, references and patent numbers.

 

Very few engines have a natural balance, straight six is one but many can either be balanced to behave in the rev bracket thy were designed to run in, like racing bikes.

 

Where the biggest problems occur is when an engine has to behave over a very large performance range and there will always be conflicts. The balance factor when tuning is always a percentage of reciprocating weight, usually between 40 and 60 % but for racing it usually closer than this at 45% to 55%

 

A good background can be found in Phil Irvings "Tuning for Speed"

 

A large part of my earlier life was spent working on and making parts for what are now classic racing bikes. In fact my whole workshop came about solely for this reason. Many were out and out exotica and specials but nor the usual spanner specials of putting a triumph engine in a [ fill the blank in ]  frame, but out and out specials where one man made everything including the patterns.

 

Denis Jones **LINK**

And Ron Phillips **LINK**

 

Are two of the better know special builders who I had a lot to do with over the years.

 

Edited By John Stevenson on 09/10/2014 02:36:15

[ronan walshParticipant @ronanwalsh98054]

Posted by Muzzer on 09/10/2014 01:49:54:

I only vaguely recall from my student days how to calculate the out of balance forces on various engine configurations and it's something I chose not to revisit although it is quite interesting. The closest twin to having perfect primary balance is the boxer (opposed pistons ) with 2 crank pins. Almost any vee is going to shake like a pig unless you use balancer shafts because the primary balance is always going to be poor in both axes. The vertical twin is a pig too, whether you have the pistons going up and down together or 180 degrees apart.

Quite well written article in Wikipedia compares various engines – including a fairly lengthy section about steam engines towards the bottom.

Murray

There are usually two angles talked about with parallel twins, namely 180* and 360*, the british twin being invariably 360* with the pistons rising and falling in unison with each other. This leads to vibration in the vertical plane as the pistons stop at tdc and bdc. 180* twins have the pistons obviously out of phase by 180* and this causes a rocking vibration.

However a real solution to vibration and associated problems (shuffling engine crankcases, crank bearing housings going out of round etc) is the 90* or 270* crank twin. It removes a lot of vibration because when one piston is at tdc or bdc the other piston is mid-stroke and therefore travelling at its fastest speed, and the pistons are never stopped together. If the vibration of a 90* 650cc twin is compared to an identically tuned 360* 650cc engine , the vibration is reduced by something in the order of 60%. Before someone says why didn't someone tell the british manufacturers about this, they did. Phil Irving who was an engineer with vincent motorcycles went around the various factories touting this idea and no one wanted to know, as the 90* engine was more expensive to make , and bsa, triumph and norton couldn't make the 360* engines quickly enough the demand was so strong. However about ten years ago Yamaha brought out an 850 twin called the trx which had a 90* engine, it didn' t sell particularly well but has a niche following.

I built a 90* crank for a triumph from a norton commando crankshaft , the two throws bolted to a central piece of en24t, if i can find some pictures i'll throw them up here. But this modification is very popular with yamaha xs650 owners and some british bike owners too !

[HopperParticipant @hopper]

And don't forget that you can still buy a brand new Enfield v-twin today, made from two Bullet top-ends joined at the hip. Google Carberry Enfield.

[Bill PudneyParticipant @billpudney37759]

This has grown to a really interesting thread!!

Seeing the TriGreeves twanged a chord with me. I built a roadgoing one in the early 70s, using a 350 Triumph T21 motor. It wasn't anything like as neat as the one earlier on though! I called mine a Grumph. It was at the time that green road bikes were becoming popular, but most were Bantams or small capacity two strokes. I wonder what became of it, I don't even remember how I got rid of it, but I rode it around for about a year.

I remember Phil Irving had an article about 270 degree cranks in Motorcycle Sport (magazine) in the early 80s, it sounded like such a good idea………….

cheers

Bill

[John OlsenParticipant @johnolsen79199]

Have to disagree with you on a couple of points Muzzer. A 90 degree V twin has perfect primary balance. It requires a balance weight on the crankshaft that balances 100% of the weight of one piston assembly.

The boxer twin would have perfect primary balance, if the two bores were in line with each other. Usually they are not, since the need for a 180 degree crank makes that difficult. So they do create a couple.

Further to the earlier discussion on parallel twins, the usual thing has been for four strokes to have the 360 degree crank and two strokes to have the 180. That gives even firing intervals on both, but of course neither has especially good balance,,,the 180 feeds a couple into the frame, which a typical motorcycle frame is not well placed to resist. Honda would be one of the exceptions, the CB350 series had a 180 degree crank, giving it a distinctive beat to the exhaust since the firing intervals were not even.

The engine that interests me a bit is the one that Brough tried at one stage. Four cylinders, opposed to each other in pairs, with each opposed pair using the same crankpin. The two cranks were geared together to rotate in the opposite direction, and all four pistons moved in the same direction at the same time. Each pair was balanced by a balance weight on their own crankshaft and so the engine had perfect primary and secondary balance, and an even firing interval. Very clever except for the need for balance weights…but if you make the same style of engine with more slices, you can even get rid of the balance weights. That gets you to an engine that is a bit much for a motorcycle, like the Napier Sabre or the BRM H 16

John

[Michael GilliganParticipant @michaelgilligan61133]

Posted by John Olsen on 09/10/2014 06:44:25:

… Honda would be one of the exceptions, the CB350 series had a 180 degree crank, giving it a distinctive beat to the exhaust since the firing intervals were not even.

.

John,

I don't remember the gory details, but in the mid-70s a friend had a CB350 which he managed to rebuild as a "split single" … Needless to say, it vibrated like one on those concrete-levelling contraptions … I do still remember the terrifying experience of my one pillion-ride.

MichaelG.

[Phil WhitleyParticipant @philwhitley94135]

Hi Michael G, It seems to be a confusion in terminology, you call them parraleel twins because the cylinders are side by side, I had always considered that in a parrallel twin the pistons went up and down together, and in a 180 twin, they were opposed, hence the vibration problem was always referred to as a problem "inherent in parralell twins" wheras 180 twins are balanced much better. Now I stand back and reconsider it all, I take your point!

Phil

[Author]

Posts