Honda V45 Magna Carb Synch and Manometer by RumRunner

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									ANDYS MANOMETER AND CARB SYNCH.DOC                                                                                           JUNE 26, 2011

Home Made 4 Channel Manometer for 1985 V45 Magna VF750C-E

Commercially available manometers are fairly expensive for the (hopefully) few
times a DIYer will need to use one. Fortunately it is relatively easy and inexpensive
to make one.

Materials List for my manometer:
         • 45” x 11” x ¼ press board,
         • 40’ of 3/8” OD (1/4” ID) plastic tube – cut into 4 10’ lengths,
         • Plastic ‘T’ connectors (two),
         • Small plastic zip ties (about 22),
         • Copper tubes ¼” OD x 3 ½” long (four),
         • Stainless or mild steel M5x0.8 hex head cap screw (four),
         • M5x0.8 hex nuts (four plus a few spares),
         • Red locktite,
         • 4 colours of vinyl electrical tape,
         • 3 double sided Velcro fasteners,
         • Coloured fluid - I used chain saw bar oil because I had it and it is thick
             enough to dampen fluctuations and provide warning before being
             sucked 10’ into the engine. On a do-over I might try tranny fluid
             because it takes a while to get bubbles out of bar oil in a small tube.

Tool list:
             •   Drill press with vice for holding screws,
             •   5/64” drill bits (possibly several!),
             •   Cutting lube,
             •   M5x0.8 tap and handle,
             •   1/8” drill bit and hand drill for zip tie holes,
             •   Pliers for tightening and cutting zip ties,
             •   Hacksaw for cutting screws,
             •   Belt sander or jigsaw for rounding corners,
             •   1” Forstner or spade bit for hanging hole,
             •   Dremel or jig saw for cutting slots on board.

         1) Drill 5/64” hole through the length of each screw – use cutting lube and don’t rush or you will find out why
              you need those spare screws!
         2) Cut the head off each screw and thread nut on until there is ¼” thread exposed,
         3) Use M5x0.8 tap to thread the inside of one end of each tube,
         4) Test fit each screw into a tube and resolve any issues before using locktite,
         5) Use red (permanent) locktite to permanently secure the screw into the tube and secure the jam-nut to the
              end of the tube. – Do not get it on the exposed ¼” of thread or wipe it off immediately. Make sure that the
              same amount of thread is exposed on each tube.
         6) Wrap 3-4 turns of different coloured tape around each tube about 1” from the open end – this helps identify
              the connection and makes it easier to handle the hot tubes after use,
         7) Let the locktite cure overnight,
         8) Round the corners of the board using belt sander, (optional but sharp corners will quickly become
         9) Bore 1” diameter hanging hole at the top of the board,
         10) Starting 12” from the bottom of the board draw 6” line with square and felt marker,
         11) Draw lines every inch for 28”,
         12) Cut about 2” of tube and use it to join the two plastic ‘T’ connectors (TT orientation),
         13) Put 10’ lengths of plastic tubes on the rest of the ‘T’ joints,
         14) Arrange the tubing over the grid with the ‘TT’ at the bottom bent as shown,
         15) Drill 4 small holes through the board to attach each ‘T’ using black zip ties,
         16) Drill 8 small holes on the bottom line to attach the tubes using black zip ties,
         17) Repeat at the 14” and top line,

Z:\Data Files\Motorcycle\Honda Magna Maintenance General\Carbs\Carb Synch and Manometer\Andys Manometer and Carb Synch.doc       Page 1 of 4
A. R. MACPHEE P. ENG.                                                                                            JUNE 26, 2011
         18) Wrap each tube near the top line with a different coloured tape for identification,
         19) Separate the tubes and trace each to the free end and apply the same colour tape,
         20) Collect the four tubes together and secure them with a white zip tie – tight enough to stay in place but not
             collapse the plastic tubes,
         21) Keep the tubes untangled and attach them together about every 6” with a white zip tie for about 2’ then
             use elastic bands for another 18”. These allow for adjustments in free length if needed,
         22) Cut a 1” vertical slot at the level of the top line, double up and thread middle of a velcro strip through and
             secure it behind the board,
         23) Cut a 1” horizontal slot at the level of the bottom line, double up and thread middle of a velcro strip through
             and secure it behind the board,
         24) Use Velcro straps attached to board to secure the free tubing for storage,
         25) To fill the manometer, plug any 2 lines, place one into the liquid of choice and suck on the last line,
         26) Getting the right amount in is a bit of luck and depends on the liquid chosen – I sucked up about 80” of
             bar oil then pulled the tube out and kept sucking until the liquid entered the gauge,
         27) Then I pulled the plugs from the 2 lines and hung them all from the ceiling over night.

Performing Carb Synch on 1985 V45 Magna VF750C-E

On a 1985 V45 Magna VF750C-E carb 1 is not synch-
able. It is the baseline and the other three carbs are
synched to it by adjusting a different linkage screw for
each carb.

The linkage screws are 7mm hex screws with a slot

Carb and cylinder numbering is:
       #1 Left rear,
       #2 Left front,
       #3 Right rear,
       #4 Right front as you sit on the bike.

Synchronization order is 3-2-4.

Tool list:
             •   Phillips head impact wrench and hammer for removing the venturi screws,
             •   8mm wrench for manometer adapter nuts,
             •   7mm open ended wrench for #3 screw,
             •   7mm hex socket with custom hex screwdriver adapter for #2 & #4 screws,
             •   Angled hex screwdriver adapter,
             •   Hex screwdriver handle.

         1) Put bike up on centre stand in an area that you can lie down on each side of the bike,
         2) Use impact wrench and a tap from the hammer to break free the venture screw on cylinder #1 – the gas
              line bracket is attached using the same screw,
         3) Remove the screw, bracket, and compression washer and put them in a dish – you really don’t want to
              lose the washers or screws!
         4) Repeat for the others,
         5) Screw the adapters in in the same colour order as they appear on the manometer #1-red etc.,
         6) Snug the adapters tight using 8mm wrench,
         7) Use free Velcro strip to hang the manometer from a mirror on the bike,
         8) Route plastic tubes over the headlight and gas tank to keep them clear of hot surfaces then match colours
              and slide them over the adapters,
         9) Start the bike while watching the manometer – if one channel might get sucked above the top level, NOTE
              WHICH ONE AND SHUT THE MOTOR OFF, adjust that screw by unscrewing it slightly,
         10) Repeat #9 until you can run the motor with all channels on the grid,
         11) Adjust the plastic idle screw to produce 1000+/-100 rpm idle – screw up to increase, down to decrease the
              idle speed,
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A. R. MACPHEE P. ENG.                                                                                        JUNE 26, 2011
        12) Synch #3 to #1 using the 7mm wrench from the left side of the bike – screw in to raise #3 and out to lower,
        13) Synch #2 to #1 using the 7mm socket, angle adapter, and screwdriver from the right side of the bike –
            screw in to raise #3 and out to lower,
        14) Synch #4 to #1 using the 7mm socket, angle adapter, and screwdriver from the right side of the bike –
            screw in to raise #4 and out to lower,
        15) Repeat 11-14 until you are satisfied – the last adjustment should be done with the bike at operating
        16) Stop engine, remove plastic tubes and adapters,
        17) Re-install venturi screws and compression washers,
        18) Start bike and adjust idle if necessary – if a significant adjustment is needed this indicates a vacuum leak
            while using the manometer so the synchronisation may be compromised – repeat if necessary.

                                              IDLE ADJUSTMENT SCREW
                                               #3 ADJUSTMENT SCREW

              #2 ADJUSTMENT SCREW

                                                #2 ADJUSTMENT SCREW

                        This picture is of the carbs as they came off the bike prior to being cleaned.

                                                                                                               Page 3 of 4
A. R. MACPHEE P. ENG.                                                                                           JUNE 26, 2011

As found – about 28” difference between #2 and #3. As left – about 5” difference between #1 and #4. Since the
specific gravity of mercury is 13.546 and bar oil is 0.886 (1/15 of mercury) this is about 1/3” mercury difference ;-).

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