Carb Synchronization

First I checked out the service manual and bluepoof. The service manual would have you take the carbs off to remove the front vacuum cap. Bluepoof suggests tee-connectors and valves. Arghh!

My 2000 SV650S has two vacuum nipples on the rear carb, one feeding the petcock, the other the fuel pump. Here's my own brand of simplification.
  1. Removed the front vacuum cap (prying from below with a very long screwdriver), and installed a 3" x 3/16" access hose, capped with an aluminum plug (confession, had to move the radiator to install the access hose), and a little retaining spring to keep the cap in place, no less. When synchronizing, the cap is removed and replaced with a 1 1/2" length of plastic drinking straw that just fits inside the 3/16" access hose (and the 3/16" differential manometer hose). I zip-tied the access hose to the fan wiring so it doesn't flop around.

  2. Pop off the air box so you can get at the rear carb vacuum nipple and the synch adjusting screw. The drain tube on the right lifts up with the airbox. Disconnect the two tubes on the left (break your fingernails on the front spring clamp, replace it with a hose clamp).

  3. Disconnect the gas line from the tank at the fuel pump. Attach an auxilliary gas supply to the fuel pump for the carb synch process.

  4. Disconnect the petcock vacuum line at the rear carb. The SV650S petcock and tank are now out of the circuit.

  5. Connect the differential manometer directly to the rear carb nipple and to the front carb access hose with the drinking straw coupler. The manometer connects to the vacuum access hose through the right fairing vent.

  6. Run the engine, twiddle the adjusting screw 'til the manometer liquid levels are equal..
Assembly is the reverse order of disassembly (CB160 Service Manual jargon).