Most of us use Carb Sticks or the like, but our friend Hans ten Broeke from The Netherlands recommended using the STE SK Synchrometer to synchronize the carburetors. You can now find a source for the meter here in the U. S. I Googled "carb flow meter" and found several places that carry it. There's a picture of the one to use below.
Ed also put together the following write-up for using the device. The basics of carb sync is covered in the various service manuals. Ed's instructions point out the difference in using the meter. The process seems to take a lot less time than with the mercury-filled Carb Sticks.
Be CAREFUL that you actually LOOK at the rubber pipes on the carbs to be sure you put the SK on the correct pipe.
As you sit on the bike:
#4 is the carb on your left next to the tank, which is directly connected to the throttle assembly and is not "adjustable" relative to the other carbs, but is adjusted by the idle adjustment knob next to the tank filler cap.
#1 is on the right front.
#2 carb is the front carb on the left side .
#3 is on the right rear.
The rubber tubes that you put the SK into sit on top of their respective carbs, but the OPENINGS to the tubes are on the OPPOSITE SIDE. Just set an rpm with the adjustment knob (next to the filler) that will assure that each carb is well off any mechanical stops (I used 2000 rpm for an "idle" speed for my tests). Then plug the SK into the tube for #4 (which opens on the RIGHT rear even though the carb is on the left rear) and take the reading. Let's say it is 4.0. Now move the SK up to the opening on the right front tube which goes to the carb on the LEFT front, #2 and adjust the screw on the shaft between the two carbs on the left side so that #2 is has the same flow as #4. Then move the SK to the tube for #1 carb (right front), which opens on the LEFT side at the front, and adjust the forward screw joining the throttles on the right two carbs so the SK reads the same flow as #4 and #2. Finally move the SK to the tube for #3 (which opens on the LEFT side, rear) and adjust the aft screw on the shaft between the two carbs on the right side to match the flows on the other carbs.
Go back to #4 and check the flow again to make sure it has not changed. If any of the carbs were way off, it will have changed because the idle speed will have changed. If #4 is no longer at the original reading then repeat the process as above. It will be correct after that. Now readjust the knob for the master idle and button it back up.
As an aside, I removed the bottom part of the airbox to do mine because it was just too hard to see and get the throttle linkage adjustment screws with it in place. If you DO remove it, remember to reconnect the little crankcase breather hose connected to the bottom side. Easy to miss.
After Ed posted his write-up, Hans responded with,
"Hi Ed,
"Nice you like the SK also.
"I only use a thin long, about 10" screw driver and a mini maglite, and don't remove anything at all besides the dummy tank and of course first, the side panels to remove the dummy tank."
Thanks to Ed and Hans for their helpful suggestions.
Editor's note: Someone pointed out to me that the sequence in the above procedure differs from what is called out in the Haynes Manual, so I've re-written it to match in the following paragraphs. However someone else, who I trust, has since told me that the Haynes procedure is "just wrong", so I recommend your keeping with the procedure as written above.
The rubber tubes that you put the SK into sit on top of their respective carbs, but the OPENINGS to the tubes are on the OPPOSITE SIDE. Just set an rpm with the adjustment knob (next to the filler) that will assure that each carb is well off any mechanical stops (I used 2000 rpm for an "idle" speed for my tests). Then plug the SK into the tube for #4 (which opens on the RIGHT rear even though the carb is on the left rear) and take the reading. Let's say it is 4.0. Now move the SK up to the opening on the right front tube which goes to the carb on the LEFT front, #2 and adjust the screw on the shaft between the two carbs on the left side so that #2 is has the same flow as #4. Then move the SK to the tube for #1 carb (right front), which opens on the LEFT side at the front, and adjust the forward screw joining the throttles on the right two carbs so the SK reads the same flow as #3 (which opens on the LEFT side, rear). Last, adjust the aft screw on the shaft between the two carbs on the right side to match the flows on the other carbs.
Go back to #4 and check the flow again to make sure it has not changed. If any of the carbs were way off, it will have changed because the idle speed will have changed. If #4 is no longer at the original reading then repeat the process as above. It will be correct after that. Now readjust the knob for the master idle and button it back up.
Last updated on February 7, 2014 © 2006-2014 M. E. Martin, All rights reserved