What's with all the flat fueling spots on the new bikes? - Page 6

 On Sat, 04 Jul 2009 22:48:30 -0700, Schiffner wrote:


US 287 / US 89 are marked on my map and in my memory as a scenic
drive.  Do you stop at the Rock Shop in Bynum?  Is Marion Brandvoldt
still kicking?

o Gadbow, Daryl. "Dino Hunter: Fossil Finder Marion Brandvold Digs,
Roaming the Ancient Coastal Plane That Is Now Montana." Lee
Enterprises Editorial Matters N. vol. (1 Dec. 2002): 96 pars. 14 Aug.
2004.
<http://lacusveris.com/The%20Hi-Line%20and%20the%20Yellowstone%20Trail/The%20Rockies/Dino_Hunter.shtml>

--
.. Be Seeing You,
.. Chuck Rhode, Sheboygan, WI, USA
.. Weather:  http://LacusVeris.com/WX
.. 75° — Wind NNW 5 mph — Sky partly cloudy.

 
Could be, never stopped there. Only times I stop are fuel and wild
life that wont move. <shrug>

 
Both of my cars have lousy low end throttle response.  IIRCC, Krusty
said it had to do with the fact the at no throttle opening FI
dispenses no fuel, whereas a carb continues to dispense small amounts
leading to smooth on/off throttle transitions.

Since you can only design one intake and exhaust system, that *system*
will have an optimal point of operation.  Yamaha has recently improved
this somewhat by having variable length throttle bodies that change
their length with rpm.

Of course, the common knowledge that bikes are delivered lean from the
factory to satisfy EPA inspectors plays a big role too.  Manufacturers
could make them run right, but often would never get them to the
showroom floor.

Two notable exceptions are the new Harleys and BMW R models.  Both
have primo throttle response sans the jerkiness associated with FI.

I have a Cobra FI enhancer on my Warrior and with the low rpm setting
set to 7 out of 10 have just about eliminated the low end jerkiness.
On my FJR I've added loads of richness to the bottom end of an
otherwise terrific FI map, but it still jerks around a lot at low
throttle openings.

In a car it isn't as big a deal since you're not leaned over when the
power hits like a bucking bronco and most people are driving them
aggressively to notice it anyway.

 

Krusty's, as usual, hasn't got it entirely right. FI systems do dispense
small amounts of fuel on a closed throttle[1][. They do this precisely
because the manufacturers know what happens when no fuel is being fed:
you get a jerky power off/power on transition.

On long, hard decelerations, yes, they shut off completely. Typically,
this may take a few seconds to come about.

You can actually feel this happening on my own K. Shut the throttle and
after perhaps four seconds' strong deceleration with the throttle closed
there's an almost imperceptible change in engine behaviour as the fuel
is cut off completely.

[1] There may be some that shut off entirely, every time you close the
throttle, mind, but the ones I'm familiar with aren't among them.


--
BMW K1100LT  Ducati 750SS  Honda CB400F & XBR500  Triumph Street Triple
Suzuki TS250ER
If you don't know what you're doing, don't do it. And RTFM.
chateau dot murray at idnet dot com

 On 28 June, 18:05, totallydeadmail...@yahoo.co.uk (The Older
Gentleman) wrote:

As a follow-up, I monitored the FI on the Triumph this morning. Shut
the throttle hard on the overrun and it definitely continues to feed
fuel through for several seconds until it reaches the point where the
computer says: "OK, he's definitely on a long-term deceleration, so
let's shut the fuel off entirely...." and the real-time fuel
consumption gauge jumps to 99.99mpg (which is its most economical
reading).