Wonky bike

[Mouse]

There's something funny going on here, either with my bike or me...

I've only had the GS for about 4 weeks, so I'm still gettng used to it. But I've noticed that the right hand air inlet pipe (the rubber pipe from airbox to cylinder head) was rubbing agaist my leg, whereas the left han one wasn't. I assumed that I wasn't sitting on the bike straight, but I'm not sure that's the case.

Anyway today I got my tape measure out and measured the distance from the footpeg to the cylinder head, on each side. The right hand cylinder head is 1.5 inches further back than the left. Hence the leg rubbing.

If I stand behind the bike and look at the engine I can actually see that it's "wonky".

Is this normal? The bike rides absolutely fine, apart from the awkward feeling that something is not straight.

 

[Deleted account W]

They're all like that sir.

They're offset.

 

[Deleted account W]

 

[Ming]

Normal

 

[Alte Wolf]

Still think your winding us up Mouse

 

[Mouse]

By gum yer right.

Now I think about it, I can see that the pistons have to be offset, both con rods can't meet the crank at the same place.

I just have to force my subconscious to believe I'm sitting centrally now!

And I keep scuffing my right shin on the cylinder when I put my foot down!

 

[(RIP) Kaister]

have a look at a moto guzzi next time you see one

 

[Emoto]

Just cut that big rubber thing off. You don't need it anyway. Tin snips ought to do the job.

 

[TheJoker]

Now I think about it, I can see that the pistons have to be offset, both con rods can't meet the crank at the same place.

BINGO!!!

I had to show that to my girlfriend when she was doing her engine design course...

 

[John Armstrong]

HD's

I think that they don't have offset ones. Or it might be some modern bike manufacturer. Seriously one crank is Y shaped and the other fits in the middle bit of the Y if I'm correct.

 

[Possu]

Re: HD's

I think that they don't have offset ones. Or it might be some modern bike manufacturer. Seriously one crank is Y shaped and the other fits in the middle bit of the Y if I'm correct.

They are offset, photos prove it. Same applies to just about any Flat /V twin/four/six/eight cylinder engine.

Harley cylinders are pretty much in line as they have a "knife & fork" style conrod set up on a common crankpin/big end - I think this is what you're referring to?

Once you have four or more cylinders configured in a Flat or V, the cylinder bore also has an effect on the cylinder offset.

 

[MikeO]

Any reason why you couldn't design an engine to have both conrods working off the same crank journal - ie have one big-end bearing for both cylinders? - just curious...

Mike

 

[TheJoker]

Any reason why you couldn't design an engine to have both conrods working off the same crank journal - ie have one big-end bearing for both cylinders? - just curious...

Mike

Mike, The Napier Railton actually has got 3!!! conrods working off one crank journal!

Couldn't find any pics of the actual engine, but here's pics of it;
http://www.brooklands.org.uk/reunion/naprail.htm

Go to Brooklands Museum to see the engine. Quite an amazing engineering feat!

I think my memory serves me in this case...

 

[Possu]

Any reason why you couldn't design an engine to have both conrods working off the same crank journal - ie have one big-end bearing for both cylinders? - just curious...

Mike

You can do, I believe Guzzi's are like that (but could be wrong?)

My point was that with a flat or v twin, even when using a single big end, the cylinders will be slightly staggered unless you use the Harley set up which is not that good. I remember being told of the downside many years ago but have since forgotten

 

[Possu]

Mike, The Napier Railton actually has got 3!!! conrods working off one crank journal!

Couldn't find any pics of the actual engine, but here's pics of it;
http://www.brooklands.org.uk/reunion/naprail.htm

Go to Brooklands Museum to see the engine. Quite an amazing engineering feat!

I think my memory serves me in this case...

Beautiful car.

I assume that if it has 3 conrods per big end & 12 cylinders, then the engine consists of 3 banks of 4 cylinders in a W configuration?

The spec sheet only mentioned capacity & number of cylinders? I'd love to see the engine.

I've seen a picture of a Harley with an extra cylinder grafted on to the front of the motor. This was a home made version, tried Googling but could not find it. I did however find this commercial version:

More here: http://www.motorcyclecruiser.com/roadtests/w3/

 

[TheJoker]

Beautiful car.

I assume that if it has 3 conrods per big end & 12 cylinders, then the engine consists of 3 banks of 4 cylinders in a W configuration?

If my memory serves, then yes, that's correct. I also think that it's got a 4 valve head....

The spec sheet only mentioned capacity & number of cylinders? I'd love to see the engine.

Go to Brooklands! It's quite an amazing place. They've actually got an engine block next to the car. I've got some pics somewhere.

I've seen a picture of a Harley with an extra cylinder grafted on to the front of the motor. This was a home made version, tried Googling but could not find it. I did however find this commercial version:

More here: http://www.motorcyclecruiser.com/roadtests/w3/

But, why would one do that on a Hardley Movingsome...?!

I would understand if someone would need two extra cylinder banks on a Hayabusa...

 

[Wraithwrider]

One of the wonders of the boxer engine is it's inherent balance with only a relatively small 'rocking couple' inbalence cause by the offset. (This being addressed to some extent on the 12 by the balencer shaft).

If you align the cylinders by putting both con rods on one crank pin you miss the point of a boxer engine completely as the thing will leap around because the mass of the moving componants will be in the same direction and not cancel out as now. Hope this makes sense!

 

[TheJoker]

More on twin engines here...

http://www.mecc.unipd.it/~cos/DINAMOTO/twin motors/twin.html