Holtzman TEMPA FLOW
The
basic operation of the TEMPA
FLOW is a pressure splitter which is connected between a source of
carb venturi vacuum and the atmosphere.
The side of the pressure splitter which is connected to the venturi
vacuum has an opening which varies in size with changes in temperature; the
opening connected to atmosphere is fixed in size. The vacuum existing
between the two openings therefore varies with temperature, and this varying
vacuum is applied to the carb float bowls through their vents. As the vacuum
applied to the float bowls increases with increasing temperature, the fuel
flow is reduced and the fuel/air mixture is leaned appropriately.
The
first thing to do when installing the TEMPA
FLOW is to READ THE
INSTRUCTION TWICE; then start the installation.
The TEMPA FLOW is set up from us to work with “true” -20F
jetting; it is important that your
carbs be jetted for -20F (-29C) and the lowest altitude at which you ride.
If you ride at colder temperatures, you jet your carbs for -40
and turn the TEMPA
FLOW adjustment screw 1/8 turn counterclockwise.
It
is important that the body be located in an area which represents as closely
as possible the temperature of the air going into the engine.
I like to see the body placed in the air box.
Normally, the adjustment screw end of the body projects outside the
air box and faces the engine, and is held in place by a tube with a clamp.
This provides access to the adjustment screw without opening the box.
Since Yamaha’s have under-hood venting (the factory vent tubes hang
down and are vented below the carbs), you do not want to vent the TEMPA FLOW in the
air box. The vent end is
connected with tubing to a fitting which places the vent outside
the air box, normally behind the box (between the box and the fuel tank).
The
TEMPA
FLOW requires a
vacuum access to the venturi vacuum of any
one carb as described above, and this is provided by installing a carb
fitting supplied with the kit. This
fitting is easily installed on the TM flatslide carbs provides on all later
Yamaha’s (except Phazer; we have a special Phazer kit).
The carb fitting installs easily in one of the slide cover plates on
top of any carb.
The
remainder of the installation requires tubing connection; the kits come
complete with all the tubing and connectors required for a twin or triple
installation.
On
initial use, we recommend turning the adjustment screw 1/8 turn clockwise to
start. This raises the turn on
temperature of the TEMPA FLOW from -20F to +5F, and provides a conservative way to
start using the product. Take
some runs at a few throttle positions, checking plugs, pistons, and/or
EGT’s to verify your set up. If
these readings allow, the adjustment screw can be rotated back to the
factory setting (or beyond if your sled has an initial state of rich tune);
the adjustment screw is an easy method of “tweaking” your jetting.
Tuning
with the TEMPA FLOW is made easier due to the elimination of the
temperature variable. All sleds
we have used with this product show consistent EGT readings over all normal
operating temperatures, and this allows tuning at any ambient temperature
without relying on jetting charts to adjust for changing temperature. If you change altitude, the adjustment screw can be turned
1/8 turn counterclockwise for every 2000 feet you rise above your jetted
altitude, and this will keep you spot-on through 6000-8000 feet of elevation
change.
The TEMPA FLOW , according to our testing and customer reports, is improving fuel economy by 20-30%. This is more than we would have predicted initially, but the reason lies in the fact that the TEMPA FLOW , because it is monitoring the temperature of the air actually going into the engine, eliminates the variable of the air box temperature rise. This allows a closer tolerance on fuel/air ratio than even jetting can provide.
Sincerely,
Barry_Holtzman President Email: holtzeng@newnorth.net
