Quote from: The Buddha on May 02, 2012, 08:27:13 PM
And comparable technology/evolution/market parallel twins will not only out perform V twins they will also be cheaper to maintain and easier to work on.

I understand the cheaper and easier maintenance part, but please explain why a parallel twin is better than a v twin configuration when it comes to performance. 

That is easy.
2 valve covers weigh more than 1, 2 cam chains weigh more than 1, 2 cam chain tensioners weigh more than 1 and make 2 X as much noise. 2 heads, 2 cyl barrels etc etc ... well they weigh more than 1 with a double cyl in it ...

Now the trick if you want to get a 90 degree twin like performance is to build a 90 degree parallel twin.
On a GS the pistons are @ TDC and BDC. It has a 180 degree crank. A xs650 has the 2 cyls rise and fall together. 360 degree crank. A mod on a xs is to make em fire @ the same time. Like a big single. Anyway the way to get a 90 degree like performance from a parallel twin is a 90 degree crank.
When one cyl is @ tdc, the other is 1/2 way up the stroke. It will even sound like a 90 V twin.
Even as a 180 degree twin it should perform close to a 90 degree twin due to the inherent advantages.
Cool.
Buddha.

On the other hand, doesn't a 90 degree v twin have less vibration? 

It also seems like the weight savings on a parallel twin might be minimal.  A valve cover is light, and while there are two heads, a parallel twin has a head that is nearly twice as big.  Offsetting the difference is the v twin's shared crankshaft. 

Don't get me wrong, I prefer a parallel twin, but mostly for maintenance and compact shape reasons.

I'll ride any naked twin 

Quote from: Juan1 on May 07, 2012, 04:29:22 PM
On the other hand, doesn't a 90 degree v twin have less vibration? 

It also seems like the weight savings on a parallel twin might be minimal.  A valve cover is light, and while there are two heads, a parallel twin has a head that is nearly twice as big.  Offsetting the difference is the v twin's shared crankshaft. 

Don't get me wrong, I prefer a parallel twin, but mostly for maintenance and compact shape reasons.

The V and parallel twins have the same type of crankshaft. There isn't any part that a parallel twin has that a V twin doesn't have. 90 V twin's have perfect primary balance, and hence can get by with less heavy counterbalancer.
This is the rough theory there. 90 degree difference means when 1 piston is @ a dead stop, @ TDC or BDC, the other is moving @ its fastest in the middle of the stroke. However a 90 crank in a parallel will acomplish the same thing, or in my xs650's case, a 277 degree crank will be close enough to a 90 that I decided to skimp on the $150 they want for a 13 tooth spline with a 7 degree offset ... only made in australia ...

Anyway, cams, cam sprokets, cam chain, are all rotating mass. Have 2 and you lose 2 X as much kinetic energy, not to mention friction and wear and the possibility there will be more crap to go wrong.
Heads, valve covers and CCT's are non rotating mass, its just dead weight. Much better than rotating dead weight. However right there your valve adjustments are now much more work, there is a need to clear out the area to work and pull another valve cover and another opportunity to drop a bolt into the cam chain tunnel. BTW a SV650 rear cyl is not just a bit more work, its like 3-4 X as much work as the front. But SV1000 is not, a different cam drive design helps that.

90 degree twins can be made out of any twin, in fact the honda shadow is a 45 degree twin with a 90 degree crank in it.

Cool.
Buddha.

Quote from: Juan1 on May 07, 2012, 04:29:22 PM
Don't get me wrong, I prefer a parallel twin, but mostly for maintenance and compact shape reasons.

A V-twin can probably be thinner. Obviously the cylinders can't be perfectly in line because the connecting rods need to be positioned next to each other, but the cylinders can over lap and are skinnier. I guarantee you'll never sit on a more compact 1200cc bike than a Buell Xb.

Quote from: The Buddha on May 07, 2012, 01:32:58 PM
That is easy.
2 valve covers weigh more than 1, 2 cam chains weigh more than 1, 2 cam chain tensioners weigh more than 1 and make 2 X as much noise. 2 heads, 2 cyl barrels etc etc ... well they weigh more than 1 with a double cyl in it ...

It sounds like we should all be riding single cylinder bikes. I'm on board, more supermotos!

Quote from: tt_four on May 08, 2012, 07:05:45 PM

Quote from: Juan1 on May 07, 2012, 04:29:22 PM
Don't get me wrong, I prefer a parallel twin, but mostly for maintenance and compact shape reasons.

A V-twin can probably be thinner. Obviously the cylinders can't be perfectly in line because the connecting rods need to be positioned next to each other, but the cylinders can over lap and are skinnier. I guarantee you'll never sit on a more compact 1200cc bike than a Buell Xb.

Yes a V twin can  be narrower, however while the SV's motor is narrow, its tank is really wide. BTW the Honda hawk of the 80's was the narrowest bloody bike I have ever set my eyes upon. So you're right, however the SV and the gladius has missed the boat on that.

Quote from: tt_four on May 08, 2012, 07:06:40 PM
It sounds like we should all be riding single cylinder bikes. I'm on board, more supermotos!

He he ... I have 2 of em ... but singles have mucho rotating mass, they tend to shake themsleves and by extension you ... and they cant have primary balance and hence have tons of rotating mass ... Cant say a single is superior to a twin in every aspect, but parallel vs V in both twin and 4 I'd go with the parallel every time.
Cool.
Buddha.