Scrambler Spied

[Dirty Duc]

Ding Ding Ding, we have a winner!

I'm kinda shocked at a single TB, but perhaps they had to do it to make room for an airbox it easier to add a turbo.

FTFY... 

[Speeddog]

 

[Curmudgeon]

Ding Ding Ding, we have a winner!

I'm kinda shocked at a single TB, but perhaps they had to do it to make room for an airbox.

Was already aware of that, so no shock (no pun) but perhaps that's where the 8 BHP went...

[Duck-Stew]

Please peruse this parts pic, and say what it is that's most surprising:

http://www.cycleworld.com/wp-content/uploads/2014/12/Scramblerparts.jpg

Holy crap...  A **single** throttle body.  Perhaps a twin-bore throttle body pair would be a quick upgrade? 

Ugh...  The way prices are cut these days (and/or emissions (either tail-pipe or noise))...

[DarkMonster620]

Type   L-Twin, Desmodromic distribution, 2 valves per cylinder, air cooled
Displacement   803 cc
Bore x stroke   88 x 66 mm
Compression ratio   11:1
Power   55 kW (75 hp) @ 8,250 rpm
Torque   68 Nm (50 lb-ft) @ 5,750 rpm
Fuel injection   Electronic fuel injection, 50 mm throttle body
Exhaust   Exhaust system with single stainless steel muffler, aluminium silencer cover, catalytic converter and 2 lambda probes
Emissions   Euro 3

[SpikeC]

 I dunno, that should add a bunch of lower end tractability to the motor. Look at the enduro versions of the old Triumphs, TR6 and T100SC, killer off road bikes with one carb. No syncing, only one cylinder sucks at a time, should make an awesome city/dirt road bike......

[Dirty Duc]

The math here seems to indicate a single 37mm TB should be sufficient.

A quick S.W.A.G. makes it look like the 800 shouldn't pull more than ~120 cfm... which even the lowest flow 50mm TB I could find beats handily.

So, the math works.  I don't know if the reality works, though the claimed HP and torque numbers seem to support it.

[Speeddog]

I dunno, that should add a bunch of lower end tractability to the motor. Look at the enduro versions of the old Triumphs, TR6 and T100SC, killer off road bikes with one carb. No syncing, only one cylinder sucks at a time, should make an awesome city/dirt road bike......

I think that assigns attributes to those motors that they already had, regardless of the number of carbs fitted.....

I'm pretty sure they did one carb as it was cheaper and didn't hurt performance too much.

And I think the 'cheaper and didn't hurt performance too much' was exactly the reason the scrambler got one TB.

[Kev M]

FWIW, since the change to EFI many mid-to-large output marine outboards which were once fed by multiple carburetors are now fed by single throttle bodies.

Also, though lower hp in the first place, the new Guzzi V7 makes more hp and torque than the previous dual throttle body version.

And the newer Guzzi California 1400 is also fed by a single throttle body.

I suspect for most non-racing applications, where the OEM is not trying to squeeze every last hp out of the motor, that most modern motors can do just fine with a single throttle body.

It does greatly reduce cost, as well as design and maintenance.

[Speeddog]

All of the motors that you've used as examples are quite low specific output (HP/liter).
The 4200cc V-6 Yamaha VMax SHO outboard makes a whopping 250HP, or 60 HP/liter.
The Guzzi V7 is 50HP, 744cc, 67 HP/liter.
And the California 1400 is 96 HP, 1380cc, so 70 HP/liter.

And thus, can work perfectly fine with a single throttle body.

My wheezy '98 M750 made 58 HP at the rear wheel on a dyno run I witnessed.
So it stomped out 78 HP/liter.
And the 750's are nothing to shout about, performance wise.

[brad black]

i can't see it being an issue.  sounds like a pretty good idea to me.  the v7 has the ecu in the throttle body too, for a very contained system.  possibly the same system.

still has a nice long inlet manifold.  and given the firing order, it's not like they're both sucking at the same time.

[Kev M]

All of the motors that you've used as examples are quite low specific output (HP/liter).
The 4200cc V-6 Yamaha VMax SHO outboard makes a whopping 250HP, or 60 HP/liter.
The Guzzi V7 is 50HP, 744cc, 67 HP/liter.
And the California 1400 is 96 HP, 1380cc, so 70 HP/liter.

And thus, can work perfectly fine with a single throttle body.

My wheezy '98 M750 made 58 HP at the rear wheel on a dyno run I witnessed.
So it stomped out 78 HP/liter.
And the 750's are nothing to shout about, performance wise.

I did add the caveat that if you're not trying to wring out every last hp for racing.

It's not just one outboard BTW, it's pretty much every single one, 2- or 4-stroke, inline or v, 3-6 cylinder, EFI or DFI, 40-300 hp, they've all abandoned multiple carbs or throttle bodies.

You'll also note the same is true for the automotive market for decades (I'm sure there is an exception).

I personally don't think it is hp/liter per se, because if that was it someone would take the expense for the advantage.

Perhaps balance is something of an issue or there is more of an advantage on twins.

Or it is just that cycle motors are being designed to work that much harder per liter.

Regardless, if we're not talking a supersport, does it really matter?

[Howie]

One of the advantages of multiple throttles pre FI was even fuel distribution.  FI reduces the need since fuel is injected at the throttle body.  One throttle body?  Loose some WOT full load power, gain some fuel economy due to throttle position (the more open the throttle at a given RPM and load, remember the BMW eta engines?)  and a big bunch of money saved.

[MadDuck]

My bet is that they will try the single throttle body for a fun, tractable bike. If they get too many complaints that the bike has no power then they will add twin throttles later. Remember that this is the new, more user friendly Ducati that we are looking at now. No more rip 'n snort up and down the model line. They might even be going the way of Honda. 

[Kev M]

My bet is that they will try the single throttle body for a fun, tractable bike. If they get too many complaints that the bike has no power then they will add twin throttles later. Remember that this is the new, more user friendly Ducati that we are looking at now. No more rip 'n snort up and down the model line. They might even be going the way of Honda. 

Trust me, the single throttle body isn't limiting the power on this bike.