Totally off every topic.

[John Orentas]

Watching the Motor GP meeting yesterday, it was said that most of the 250's were two stroke 'V' twins. Never heard of such a thing.

 

Common big end bearings?, isolated crank-cases?. OK engine nerds, how does all that work then ?

Edited June 4, 2007 by John Orentas

[carlt]

Watching the Motor GP meeting yesterday, it was said that most of the 250's were two stroke 'V' twins. Never heard of such a thing.

 

Common big end bearings?, isolated crank-cases?. OK engine nerds, how does all that work then ?

Dunno but I went to look at a boat once with a 'boxer' horizontally opposed twin. That was pretty cool.

[Hairy-Neil]

Common big end bearings?, isolated crank-cases?. OK engine nerds, how does all that work then ?

 

There's little new in automotive engineering, its pretty much all been tried before....including, believe it or not, a 2 cylinder two stroke with a common combustion chamber.......

[Sir Nibble]

a 2 cylinder two stroke with a common combustion chamber.......

Yea, the old Sachs/puch split single. A lovely idea when you look at it closely. " stroke V twin? why? Surely there are problems with that that wouldn't occur with a 180deg parallel twin. I would like to see that in bits to work out why they've done it. If you think about it, with a shared crankpin only one cylinder would run.

[Hairy-Neil]

Yea, the old Sachs/puch split single. A lovely idea when you look at it closely.....

 

There was a British built engine to this design raced (in a motorcycle) with some success in the 1950's. (Ellrich? Ullrich?) The British Motor Corporation (BMC) bought the rights to it and developed a water cooled version for use in the still-born, Austin A20 project.......Prototypes were built for a lightweight aluminium bodied car based on the A30's design. See 'Post War Baby Austins' Sharratt, 1988, Osprey, ISBN: 0850457106

 

 

The engine survived and was in the hands of the A30/A35 Club c.20 years ago and was run-up at the 1986 National Rally. However, it has since been 'lost' whilst in the custody of a club trustee. The incomplete remains of an air cooled version of the same engine survive, last I knew in the British Motor Heritage museum at Gaydon, Warwickshire.

Edited June 4, 2007 by Hairy-Neil

[John Orentas]

Yea, the old Sachs/puch split single. A lovely idea when you look at it closely. " stroke V twin? why? Surely there are problems with that that wouldn't occur with a 180deg parallel twin. I would like to see that in bits to work out why they've done it. If you think about it, with a shared crankpin only one cylinder would run.

 

 

Well exactly, a true V twin must by definition have a single or shared big end so only one crankcase, I must find out.

 

As you all say there are dozens of permutations, also an excelsior 3 cylinder with the 3rd used only for compression. Commer made a weird horizontally opposed 4 cylinder diesel with a single crank. I used to play about with a twin Rotax years ago but that had 2 cranks.

 

I remember professor Ullrich (I think) Dublin University, he did a lot with Rotax or Brigadier as it became known, I have no recollection of a BMC connection though.

[Hairy-Neil]

...... Commer made a weird horizontally opposed 4 cylinder diesel with a single crank.

 

But 2 stroke diesels don't have the problem of transfer ports and crankcase compression.....The fuel comes from an injector, the air is blown in by a supercharger......

 

BTW, it was a 3 cylinder 2 stroke John, the Commer TS3. I understand Rootes were developing a 4 cylinder version in an attempt to squeeze more horses from it when they were swallowed up by Chrysler around 1969.

 

 

And of course not forgetting the Napier Deltic 18 cylinder, 36 piston, 3 crankshaft 2 stroke unit used in rail locomotives on the east coast mainline...

[Timleech]

But 2 stroke diesels don't have the problem of transfer ports and crankcase compression.....The fuel comes from an injector, the air is blown in by a supercharger......

 

Not always. The Bolinder, Widdop, Petter 'S' & other similar 2-stroke diesels & semi-diesels used crankcase compression.

Multiple cylinders? No problem, just use a multiple or divided crankcase.

 

BTW, it was a 3 cylinder 2 stroke John, the Commer TS3. I understand Rootes were developing a 4 cylinder version in an attempt to squeeze more horses from it when they were swallowed up by Chrysler around 1969.

And of course not forgetting the Napier Deltic 18 cylinder, 36 piston, 3 crankshaft 2 stroke unit used in rail locomotives on the east coast mainline...

 

Rootes were certainly working on a turbocharged version of the TS3.

And Listers marketed a marine version of the TS3, the Rootes-Lister

which like the commer TS3 had a *Roots* (no 'e') blower.

 

Tim

[Tony Brooks]

Watching the Motor GP meeting yesterday, it was said that most of the 250's were two stroke 'V' twins. Never heard of such a thing.

 

Common big end bearings?, isolated crank-cases?. OK engine nerds, how does all that work then ?

 

 

Perhaps its a design that "went the rounds" just before "pollution" caused two strokes problems.

 

From memory a University (possibly Warwick) were developing a two stroke with a stepped piston driving the crank via cross-head type thing and conrod.

 

The cylinder was also stepped so the larger volume bottom part pumped the mixture into the upper combustion chamber section. This allowed a "normal" crankshaft and big end type Assembly with no danger of getting fuel mixed up with oil.

 

 

Tony Brooks

[John Orentas]

Beginning to regret starting all this, I think the 2 stroke diesel you are all thinking about is probably the Cummins. Beautiful all aluminium high revving engine with Routes Blower. The Commer was a pretty crude contraption with bell cranks and rods connecting the pistons to the cranks. The engine was usually mounted midships between the chassis members.

 

Tony, the stepped piston idea was very much 1950's DKW was one of them and I think DMW another. I am taking about a 100 bhp 250 bike racing last Sunday.

 

And Tim, think about it, how do you have a divided crankcase with a 'V' twin, that's the whole point.

[Timleech]

Beginning to regret starting all this, I think the 2 stroke diesel you are all thinking about is probably the Cummins. Beautiful all aluminium high revving engine with Routes Blower. The Commer was a pretty crude contraption with bell cranks and rods connecting the pistons to the cranks. The engine was usually mounted midships between the chassis members.

 

I certainly wasn't thinking of a Cummins 2-stroke, in fact I wasn't aware that they ever made one.

Maybe you are thinking of the GM/Detroit Diesel 2-stroke? That certainly used a ROOTS blower, as did the TS3

Here's a link to info on the Rootes-Lister:-

 

http://www.oldengine.org/members/diesel/technical/TS3.htm

 

Tony, the stepped piston idea was very much 1950's DKW was one of them and I think DMW another. I am taking about a 100 bhp 250 bike racing last Sunday.

 

And Tim, think about it, how do you have a divided crankcase with a 'V' twin, that's the whole point.

 

I wasn't referring to your motorbike engine (Suzuki based?), though I don't see why a divided crankcase shouldn't be contrived, more about the older marine 2-strokes such as Bolinders. I don't understand the suggestion that a V-twin must use a shared crankpin?

 

 

Edited to iclude a link

Tim

Edited June 5, 2007 by Timleech

[Sir Nibble]

a stepped piston

That's quite likely the answer! Remember the abortive Norton Wulf of the 1970s? Whatever, it still begs the question, why? The Japs are past masters at squeezing out horsepower that no one else knew was there and they must have a good reason.

[Hairy-Neil]

I certainly wasn't thinking of a Cummins 2-stroke, in fact I wasn't aware that they ever made one.

 

Tim

 

Foden was another UK company to use the two stroke diesel in their trucks. The Commer TS3 may have been a crude design but hauliers that used them reported many hundred thousand trouble free miles from the units. It was progress that left them behind, not bad design......

[Phil Speight]

Watching the Motor GP meeting yesterday, it was said that most of the 250's were two stroke 'V' twins. Never heard of such a thing.

 

Common big end bearings?, isolated crank-cases?. OK engine nerds, how does all that work then ?

Everything everyone has said is absolutely right ( I`m a bike freak - although I am currently without one) but even something as mainstream as a Honda RS 250 or a Suzuki RG 250 , both in production for road use until quite recently , were 2 stroke v-twins with a single crankcase.

Cheers

Phil

Edited June 6, 2007 by Phil Speight

[John Orentas]

Everything everyone has said is absolutely right ( I`m a bike freak - although I am currently without one) but even something as mainstream as a Honda RS 250 or a Suzuki RG 250 , both in production for road use until quite recently , were 2 stroke v-twins with a single crankcase.

Cheers

Phil

 

 

Don't think you have quite got the point either Phil. Unless you have some form of supercharger which these bikes certainly don't have, two stroke cylinders can't share a crankcase and if there are 2 crankcases they are not proper V twins.

 

I am still trying to find out what the format is.

[Gibbo]

Don't think you have quite got the point either Phil. Unless you have some form of supercharger which these bikes certainly don't have, two stroke cylinders can't share a crankcase and if there are 2 crankcases they are not proper V twins.

 

I am still trying to find out what the format is.

 

I think they are if the crankcase is separated vertically like the moto GPs do.

 

Gibbo

[John Orentas]

I think they are if the crankcase is separated vertically like the moto GPs do.

 

Gibbo

 

 

That is probably the most likely answer though if they don't share a big end bearing it could be said they are not a true V twin, more a 'not quite vertical twin'. The 900 Moto GP bikes are 4 strokes so crankcase isolation is not an issue.

[Gibbo]

That is probably the most likely answer though if they don't share a big end bearing it could be said they are not a true V twin, more a 'not quite vertical twin'. The 900 Moto GP bikes are 4 strokes so crankcase isolation is not an issue.

 

I have no idea I just emailed a mate who's mad about bikes. He said.... "the big ends are in the same place (ie next to each other) but there's a vertical wall between them so the balance remains the same but each piston can compress its own cylinder". Which may aswell be Dutch.

 

Gibbo

[Timleech]

That is probably the most likely answer though if they don't share a big end bearing it could be said they are not a true V twin, more a 'not quite vertical twin'.

 

I don't understand that contention. If there are two cylinders in a vee formation, then it's a vee twin, surely?

Some makers use in effect a 2-throw crank to try to get smoother running, but they're still vee twins.

Or am I missing something?

 

Tim

[Phil Speight]

Don't think you have quite got the point either Phil. Unless you have some form of supercharger which these bikes certainly don't have, two stroke cylinders can't share a crankcase and if there are 2 crankcases they are not proper V twins.

 

I am still trying to find out what the format is.

I do understand honest - crankcase compression , porting etc. However , I still think the RGV at least had only one crankshaft and therefore perforce one crankcase. So ; I `m off to look at me mates RGV this very evening and will report back in`t morning.

This is a major sacrifice that I hope you all appreciate becuase every time I see the damn two stroke toy I`m reminded that it is , in fact, probably quicker than my old Jota used to be. Me mate also keeps telling me to get some insurance and borrow it for as long as I want. It`s Japanese, it`s a two stroke, it`s coverd in factory applied Lucky Strike stickers AND I`M NOT A GIRL......................on the other hand the sun shines and I do miss having a bike.

Cheers

Phil

[Timleech]

Don't think you have quite got the point either Phil. Unless you have some form of supercharger which these bikes certainly don't have, two stroke cylinders can't share a crankcase and if there are 2 crankcases they are not proper V twins.

 

I am still trying to find out what the format is.

 

 

Look at

 

http://www.suzukirgv250.co.uk/ServiceManua...03/jpg_3-29.htm

 

Clearly shows a 2-throw crank and divided crankcase.

 

Tim

[John Orentas]

Look at

http://www.suzukirgv250.co.uk/ServiceManua...03/jpg_3-29.htm

Clearly shows a 2-throw crank and divided crankcase.

 

Tim

 

 

Sorry, that is not a V twin, it is a parallel twin clearly showing two separerate con rods and big end bearings.

 

From Wikepedia :-

 

True V-twin vs V-2

In a true V-twin engine, for example Harley Davidson engines, the two cylinders share a single crank pin (also known as a journal) on the crankshaft, therefore the "twin" nomenclature. Two cylinder, V shaped engines with separate crank pins for each cylinder are more properly called "V-2" engines, however, proper identification of V-2 engines is uncommon. They are frequently referred to as V-twin engines, too, although this is technically incorrect.[citation needed]

[Timleech]

Sorry, that is not a V twin, it is a parallel twin clearly showing two separerate con rods and big end bearings.

 

Well it's from the makers' manual for a Suzuki RGV250, which on page 1-9 says

"Engine type - Two-stroke, watercooled, 90deg V-TWIN"

 

http://www.suzukirgv250.co.uk/ServiceManua...n01/jpg_1-9.htm

 

From Wikepedia :-

 

True V-twin vs V-2

In a true V-twin engine, for example Harley Davidson engines, the two cylinders share a single crank pin (also known as a journal) on the crankshaft, therefore the "twin" nomenclature. Two cylinder, V shaped engines with separate crank pins for each cylinder are more properly called "V-2" engines, however, proper identification of V-2 engines is uncommon. They are frequently referred to as V-twin engines, too, although this is technically incorrect.[citation needed]

 

Ah, it says so in Wikipedia so it must be true

I must admit that I'd never been aware of that distinction, but it sounds as though most people ignore it anyway

Your original post was referring to V-twins, but were they really (according to your quoted definition)?

 

 

Tim

[anhar]

...

Ah, it says so in Wikipedia so it must be true

I must admit that I'd never been aware of that distinction, but it sounds as though most people ignore it anyway

Your original post was referring to V-twins, but were they really (according to your quoted definition)?

Tim

Quite. I've been riding motorcycles for over forty years and have owned quite a few including several Harleys amongst many others. I have never heard of this distinction between V twin and V2 either and I think it's nonsense even though Harleys are described as "true" V twins in that definition. It's just a hairsplitter's argument. Any configuration of two cylinders in a V is known as a V twin. This descriptive style is merely a shorthand bit of jargon to describe the general configuration of an engine so that people can communicate easily, same as saying V6 or inline four or whatever and is not meant to be a working explanation of all the internal arrangements which may vary between engines.

 

regards

Steve

[DHutch]

And im suppost to be revising as well!!

- I think neils right tho, its all about the napier deltic.

 

Unfortunatly the 55s website seams to be no-longer in existance, which is a great shame as it had some very in-depth photos of the rebuild and contained some of the best 'deltic' photos ive seen, however the are a few photos here, and many others if you spend time looking for them.

- http://www.napierchronicles.co.uk/mcf_photo_406.htm

 

http://en.wikipedia.org/wiki/Napier_Deltic

 

 

Daniel