home made 4 channel manometer for v45 magnav4musclebike.com/articles/magnandy/andy's manometer...

ANDYS MANOMETER AND CARB SYNCH - REV 3 - JULY 12 2013.DOC JULY 12, 2013

M:\000 - Files\Motorcycle\1984 V45 Magna\Carbs\Carb Synch and Manometer\Andys Manometer and Carb Synch - rev 3 - July 12 2013.doc of 6

Home Made 4 Channel Manometer for V45 Magna Commercially available manometers can be 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:

• 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 plus a few spares),

• M5x0.8 hex nuts (four),

• 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. Instructions for making the adapters: Adapters can be purchased from Honda or off the internet – get the 5mm thread. They will work for any Honda bike. If you buy the adapters you will have to use a smaller diameter tube that fits on the adapter. To make the adapters:

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,

A. R. MACPHEE JULY 12, 2013

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Instructions for making the manometer: The following instructions are for duplicating the manometer that I made. You can make a more basic but still fully functional manometer from anything rigid enough to attach the tubing to – including a stiff piece of cardboard or an old fence board. Here is what I did:

1) Round the corners of the board using belt sander, (optional but sharp corners will quickly become damaged),

2) Bore a 1” diameter hanging hole at the top of the board, 3) Starting 12” from the bottom of the board draw 6” line with square and felt marker, 4) Draw lines every inch for 28”, 5) Cut about 2” of tube and use it to join the two plastic ‘T’ connectors (TT orientation), 6) Put 10’ lengths of plastic tubes on the rest of the ‘T’ joints, 7) Arrange the tubing over the grid with the ‘TT’ at the bottom bent as shown, 8) Drill 4 small holes through the board to attach each ‘T’ using black zip ties, 9) Drill 8 small holes on the bottom line to attach the tubes using black zip ties, 10) Repeat at the 14” and top line, 11) Wrap each tube near the top line with a different coloured tape for identification, 12) Separate the tubes and trace each to the free end and apply the same colour tape, 13) 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,

14) 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,

15) 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,

16) 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,

17) Use Velcro straps attached to board to secure the free tubing for storage, 18) To fill the manometer, plug any 2 lines, place one into the liquid of choice and suck on the last line, 19) 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,

20) Then I pulled the plugs from the 2 lines and hung them all from the ceiling over night. Improvements to the initial design: Another V4Musclebike.com member made the same manometer but added a simple improvement – HondaCrazy added a valve in each line near the top of the board. When the valves are closed, the manometer can be laid down flat without the fluid running out. I plan to get 4 aquarium air bubbler in-line valves from my local pet store to add to my manometer if I can find the right size. After using my manometer a few times I found that the plastic tube was getting stretched from the engine heat in the copper tube and the tubes began to lose their seal and leak – obviously not a good thing. I cut just over an inch off to get back to undistorted tube. I then cut about an inch off the copper tubes and inserted a length of rubber fuel line to act as a thermal insulator. Selecting a fluid: Another V4Musclebike.com member made the same manometer but used 2-cycle oil. Initially he found that it was so thin that it moved very rapidly and was sucked into the engine before he could kill the engine. After adjusting the carbs so that they were more balanced, he was able to connect the manometer without the oil being sucked into the engine – only to find that the oil was being boiled away by the vacuum pressure. The oil is designed to be vaporized in a 2-cycle engine after all. A lighter (lower specific gravity) fluid will have a greater movement for a given applied vacuum difference. A thinner (lower viscosity) fluid will move faster for a given vacuum difference. It is also important to use a fluid that will not harm the engine if it is drawn in. Chain saw bar oil worked well for me – and was very easy to see.


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Performing the Carb Synch For 700-100cc bikes, carb 1 is not synch-able. For 500cc bikes, carb 4 is not synch-able. The un-synch-able carb is the baseline and the other three carbs are synched to it by adjusting a different linkage screw for each carb. The thumb screw on the un-synch-able carb adjusts the idle speed – screw it in (upwards) to increase the isle speed. Adjusting the idle speed can be done at any time during the synchronization to keep the rpms near the target range for the model:

500cc 1,300 ± 100 rpm 700cc 1,200 ± 100 rpm 750cc 1,000 ± 100 rpm 1100cc 1,000 ± 100 rpm

The linkage screws are 7mm hex screws with a slot head. 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 usually given as 3-2-4 for V45’s and V65’s but the only critical order is that 4 must be done after 2. For V30’s the synchronization order is usually given as 3-2-1 for V45’s and V65’s but the only critical order is that 1 must be done after 3. 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. Instructions:

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, (the locations for #3 & #4 are shown in the picture)

5) Screw in the adapters 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,


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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, 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 #2 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

temperature, 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.

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

#3 ADJUSTMENT SCREW

#4 ADJUSTMENT SCREW

#2 ADJUSTMENT SCREW

IDLE ADJUSTMENT SCREW


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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

th of mercury) this is about 1/3” mercury difference ;-).

My Clymers Manual sets 2.4” Hg at the limit below which the carbs are considered to be synchronized – that is more than the entire range of this sensitive manometer.


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Second Generation Manometer Design in use

After using my original manometer design several times I found that the engine heat was being transmitted thru the copper tubes to the end of the plastic tube – not a big surprise. I also found that this heat was causing the plastic tube to be less tight on the copper tube – and possibly allowing some leakage and affecting the results. To correct this design flaw I cut the original copper tubes in half and used a section of rubber fuel line as a thermal block to join the copper tubes. Next I cut the already heat affected ends off the plastic tubes and I was done.

Here’s the modified manometer connected to my Goldwing.

When I started the motor one of the columns was headed thru the roof and one was almost dropping into the connectors at the bottom. I know that if it gets there it will draw air into the manometer and I’ll have to wait a while for the air to work its’ way out. I turned the motor off and adjusted #3 screw out and #2 in. On the restart the levels stayed within range and I was able to do the balancing. After all the adjustments were done the maximum difference was about 1” – which is equivalent to 1/15th “ of mercury – well within limits.

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