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v twins or inline 4

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stinkwheel
Bovine Proctologist



Joined: 12 Jul 2004
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PostPosted: 19:33 - 25 Mar 2008    Post subject: Reply with quote
Kickstart wrote:
Hi

Definatly. Trouble is that it is difficult to package a V twin or V4 withouth having the clutch, ignition and alternator hanging out. The inline engines have a load of space behind the cylinders where they can put all that.

All the best

Keith


They just have no imagination, that's all. They are just pointing the V the wrong way. Loads of room behind the engine if the front cylinder is paralell to the ground
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.
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stinkwheel
Bovine Proctologist



Joined: 12 Jul 2004
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PostPosted: 19:45 - 25 Mar 2008    Post subject: Reply with quote
G wrote:
Back to the parallel twin, then Smile.


I for one, think this is a much maligned and under-utilised engine configuration. It's never really been "Done" with any seriousness other than in the 2-stroke arena.

The only vaguely 'sporty' 4-stroke paralell twin I can think of to come out of Japan is the GPZ500 and that's a bike that punches well above its weight. (600/4 owners can shut up unless they want to try racing one on a 1987 600/4)

It's one of the reasons MZ built a 1000cc paralell twin, the Japs couldn't accuse them of copying (ah, the irony).
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.
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Kickstart
The Oracle



Joined: 04 Feb 2002
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PostPosted: 20:11 - 25 Mar 2008    Post subject: Reply with quote
G wrote:
To be fair, I don't think any of the modern four cylinder sports bikes have serious issues with ground clearance


Partly that is front moving the engine higher.

stinkwheel wrote:
They just have no imagination, that's all. They are just pointing the V the wrong way. Loads of room behind the engine if the front cylinder is paralell to the ground


A bit of space, but then you have problems with having the weight far enough forward as there has to be enough space between the crankcases and the front wheel to fit the front cylinder. Move the crank up a bit and have the gearbox under it, with the bottom cylinder pointing down and there would be space to move the engine back in the frame.

Either way there are still issues getting things like the clutch out of the way. On a 4 they can put the primary drive between a couple of the cylinders while on a proper V twin it pretty much has to go on the end of the crank, so the clutch is likely further out than the ends of the crank.

stinkwheel wrote:
The only vaguely 'sporty' 4-stroke paralell twin I can think of to come out of Japan is the GPZ500 and that's a bike that punches well above its weight. (600/4 owners can shut up unless they want to try racing one on a 1987 600/4)


Probably the TRX850 engine (derived from the XTZ750 via the TDM850) would be a better basis. Canted forward gave the space to hide things behind the cylinders, except Yamaha didn't bother.

The GPZ engine started life in a 450cc custom, and somehow managed to survive such an inauspicious start.

Al the best

Keith
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stinkwheel
Bovine Proctologist



Joined: 12 Jul 2004
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PostPosted: 20:22 - 25 Mar 2008    Post subject: Reply with quote
Kickstart wrote:

The GPZ engine started life in a 450cc custom, and somehow managed to survive such an inauspicious start.


Kind of what I was getting at. The engine first saw the light of day in 1985 as an EN450 and is still in production 23 years later in the KLE500.

Maybe time someone designed a new one with modern design and materials?
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.
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Tango675
Crazy Courier



Joined: 24 Jul 2007
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PostPosted: 20:23 - 25 Mar 2008    Post subject: Reply with quote
BMW prove that these days you can tune and develop an engine to do everything with some electronic wiz-bang (see their boxter twin). It will inherently be better at some things than others, for example, it won't make a particualy good race engine but it will make a nice touring engine and maybe even do a bit of off-roading.

The IL4 is the best selling engine fitted to the most motorcycles (~600cc+) because its what most people want at a price they can afford. And if you happen to knock out car engines too...

However not everyone wants a IL4, so you can take your pick of any other engine configuration in various states of tune.
Would a harley be a harley with an IL4? A lot of the bikes character comes from the engine.

V-twins cost more to manufacture (2 heads) and produce more vibrations than a IL4 but are easy to tune for torque and reasonable power. They also fit easily into a motorcycle frame. Lots of people like them because of the noise (including myself Very Happy )

A V4 takes on the caractoristics of both a V-twin and IL4, but costs more to manufacture again (two pairs of heads). Honda believe that this is the optimum engine for a motorcycle, but have still to prove this to everyone else (as they are the only people who make them).
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Kickstart
The Oracle



Joined: 04 Feb 2002
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PostPosted: 20:43 - 25 Mar 2008    Post subject: Reply with quote
Goat-Boy wrote:
V-twins cost more to manufacture (2 heads) and produce more vibrations than a IL4


Proper V twin has less vibration than an IL4.

Goat-Boy wrote:
(as they are the only people who make them).


Not really. Aprilia are just launching one. Yamaha have made a few (V Max, various tourers, could even argue for the RD500), Ducati developed one a few decades ago (as well the the recent Desmosedieci).

All the best

Keith
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Tango675
Crazy Courier



Joined: 24 Jul 2007
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PostPosted: 22:27 - 25 Mar 2008    Post subject: Reply with quote
Kickstart wrote:
Goat-Boy wrote:
V-twins cost more to manufacture (2 heads) and produce more vibrations than a IL4


Proper V twin has less vibration than an IL4.


How?

Unless you have a two stroke, you are always going to have uneven combustion between the two cylinder. The advantage a twin has, is if they are mounted at 90 or 180 degrees to each other. This is because the forces are more balanced, however this will still produce more vibration than an IL4 with the same CC as you have two larger lumps of metal trying to move apart from each other. The only way to counter this is with weights or a big flywheel.
An IL4 has more even combustion over the 4 cylinder and therefore produces less vibrations naturally. Again you can "fix" this with weights or a big flywheel, but these will be lighter than the V twin.

Just think how much vibration you get with a single, then how much you get with a V2, IL4, IL6, V6, V8, V12 etc. It goes down each time, because of the bigger overlap on combustion.

Glad to hear Honda have been joined by a few others on the V4 front. It is a good engine choice for a motorbike (compact and narrow), just expensive to make, so it only really appears in the more exotic bikes.
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Kickstart
The Oracle



Joined: 04 Feb 2002
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PostPosted: 22:54 - 25 Mar 2008    Post subject: Reply with quote
Goat-Boy wrote:
Just think how much vibration you get with a single, then how much you get with a V2, IL4, IL6, V6, V8, V12 etc. It goes down each time, because of the bigger overlap on combustion.


That is only one of many causes of vibration. Of your examples there the IL4 is about the worst!

For a very brief description.

https://en.wikipedia.org/wiki/Engine_balance

All the best

Keith
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Old Thread Alert!

The last post was made 16 years, 38 days ago. Instead of replying here, would creating a new thread be more useful?
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