[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

EFI and great book... and here's a surging solution

Since some folks find the TB cross-over tube beneficial and some not. It
could be that Tom's cross-over is more restricted in as much as the tee is
still in place. When you are sipping aromatic vapors, tube ID is immaterial
but not when you are re-balancing the TPs. Surely possible to run a less
restrictive cross-over.

Apropos cross-overs and White-Out marks (which indicate how far you've
twisted the throttle), next time on the highway (that's June in Toronto...
only kidding), you could check to see how far the throttle is twisted. I bet
it is a whole lot less than many suppose. Therefore, even little cross-over
tubes can help re-balance even at highway speeds, esp. with the tee replaced
by the largest ID pipe possible.

It is interesting how the bypass screw on a TP is different than a carb. On
a carb, the position of the butterfly not only influences air flow, but also
relationship to the progression holes, air stream from the slide cutout,
etc. On a TP, you are essentially trying to keep two parameters in proper
relationship, (1) the air flow summed from both the butterfly and the bypass
and (2) the TPS signal. The bypass adjustment therefore influences the the
TPS signal. To enrichen the mixture for a given volume of air, you would
therefore use a relatively smaller bypass opening which would result in a
relatively larger butterfly opening (and call for more fuel via the TPS).

A great book is "Motorcycle Fuel Injection Handbook," Adam Wade, Motorbooks,
2004 - in stock at Amazon or equally conveniently from the Toronto Public
Library for free (the only benefit I can think of for being an urban biker).
While acknowledging their early entry into the field, he does not seem
favorable to Bosch's Air of Mystery or to the rather skimpy set of sensors
they use. Bigger Air of Mystery from all the chip magicians - BB Power, FIM,
Laser... all secretive. Very good read but helpful only in the abstract, for
those who like to ride in the abstract. In thinking about the new Power
Commander, provides good prep.

The simple-as-could-be solution to closed-loop surging within the scope of
the stock set-up and logic is to install a non-stoich O2 sensor - one that
goes "burp" just a bit richer than the stock unit. Now I don't know if
anybody makes such a thing, but it sure would be a smooth-as-spit solution.

Personal note: after 38 years as an Airhead and two major carb switcheroos,
I truly believe that there is no need for anyone to take time to teach me
the nature, purpose, and non-adjustment of the throttle stop screw, as nice
as the intention may have been.


- -- 
Ben Barkow, Toronto... 39 seasons on Beemers, 44 as a biker,
1961 R69s, 1967-1999... really sup'ed up and fast
1984 R80RT/rod, 1998- 5 extra peak ponies in a wider flatter power band,
  much modified 2-into-1 exhaust, CR 9.5, Keihin PJ 34mm oval carbs,
  dual-rate springs with cartridge emulators, BT45/S11, Saeng fairing
1999 R1100S, 2004- Leo Vince exh, JetHot coatings, Ben's windscreen

and.... 1960 Jaguar MkII (SUs), 1964 Alfa Romeo GTV (FI),
  1968 Lotus Elan Plus 2 (Webbers), 1987 Maserati 425 Biturbo (Webber),
  and next... the rocking chair (legpower model)