Homemade Carburetor Synchronizing Gauge
My objective was to make simple, convenient, inexpensive and reliable gauge
by using only readily available materials. I happened to have an old
3-½-diameter vacuum & pressure gauge and that is what came very handy. I
had to buy only vinyl tubing which cost me about $ 2.5.
Note: The overall size of the stand is approximately 7 inches wide and 12
inches toll. The base is 8 inches by 8 inches and approximately 30 degree
inclined from the vertical.
. ¾ inch diameter sprinkler pipe 6 inches long
. Two end caps for the above pipe
. ¼ diameter OD, 3/16 inch ID vinyl tubing 30 ft. long (8 cents/ft)
. Six small size binder clips to clamp the tubes.
. Scrap 1-inch thick wood pieces.
. Some nails & screws as required
. 3/16 inch OD, metal tube (I used old brake lining but any metal or plastic
tube or readily available1/8 inch plastic nipples will also work)
- Drill six holes approximately 3/16 diameter holes, ¾ inch apart on bottom
of the vacuum manifold and one hole on the top.
Note: Make sure that the slightly tapered end of the metal tube is fairly
tight to make leak proof connection.
- Cut seven 1½ inch long pieces from the metal tube. Debar each end. Make a
small taper on one end. This end will be pushed into the vacuum manifold.
- Use supper glue or such cement around all the seven joints. This is to
further assure leak proof connections.
- Blow any dirt from inside the manifold
- Install the two end caps by using typical PVC compound.
- Use your own design to make the stand and the base. I used 1-inch scrap pine
- Right above the manifold, I also put two hooks to store the tubes.
- On each side of the vertical piece and above the manifold, I put two 2 ½
nails to store the binder clips.
- Nail a guide piece at the bottom of the vertical made from ¾ inch square
wood and drill six 5/16 diameter holes ¾ inch apart. I marked the six
cylinder numbers. Right side with 1,3, 5 and left side with 2,4,6
- Cut three pieces each of 60 inches for the left side and three pieces each
of 40 inches long for the right side.
- Prepare 12-inch long extension piece out of the tube to be used on number 6
Note: This piece has 3/16-inch nipple (made from the same metal tube) on
one end and a 3/16 T in the middle (I used plastic T)
- Put the gauge on the right side of the bike on a stool or chair.
- Thread the long tubes over the top radiator hose in the front or at the
rear end of the engine but make sure they do not touch any hot component.
And bring them on the left side of the bike.
- Remove three plugs from cylinders 1,2 and 5 and save them.
- Remove the three vacuum lines Install the two left side tubes on cylinder
2 and 4 intakes.
- Remove the vacuum line from # 6 intake. Please note that this line
provides vacuum to the petcock to keep it open when the engine is running.
- Install the nipple end of the extension to the line removed in the above
step # 4 and install the other end on the # 6 intake.
- Connect the # 6 tube from the gauge to the T of the extension piece.
- Using the binder clips, pinch all the lines except # 6. I pinched at few
inches below the guide but can be done even close to each intake. In
pinching, I bent the tube and then put the binder clip on the end. One can
also use the plastic or wood pins for hanging clothes.
- Start the engine and when it is wormed up, pinch the #6 intake tube
upstream of the T. This will assure that the vacuum is retained and the
petcock will remain open to supply the fuel.
- Remove the clip from #3 intake and note this reading. Please note that the
#3 intake is the reference intake and there is no adjusting screw on this
carburetor. Our objective is to set all the remaining carburetors to this
reference reading by using the adjusting screws.
Notes: 1. Make a simple table with six intake numbers across and ‘as
found’ and ‘as left’ on the left. I believe, it is a good historical
data for the future comparison.
- Pinch the #3 and complete all the intake readings one at a time.
- Shut the engine off.
- Reinstall the plugs on # 1,2,and 3
- Reconnect all the vacuum lines including #6 per original set-up
- Start the engine to make sure it runs again as expected.
Note: For any clarification, please contact.
Also, use service manual or the
chapter in The Valkyrie Maintenance Guide by Carl Kulow.
Ami B. Sidpara
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