RG500 Carb Sync - Manual


Make sure that the cables are routed correctly to their respective carbs. The cables are numbered at the junction from 0-4 with 0 being the oil cable. The oil cable runs under the right rear exhaust pipe on its way to the pump.
The cylinders are numbered LF=#1, RF=#2, LR=#3, RR=#4.
The longer of the two choke cables goes to the #4 carb.
Run all the carb top cable adjusters completely in and back out 2/3 turn, leaving the nuts loose for now.
Adjust the cable slack at the grip to have a 2-3 mm of play.
Wrap some 1/8” vinyl hose (or clothes line, or 12ga wire, etc.) 1.5 times around the throttle between the stock grip and the housing to act as a friction brake to hold the throttle stationary while synchronizing the carbs.
If the grips aren't stock (or you just like using shiny tools), you may want to use a vise grip lightly cinched onto the grip with the handle resting on the brake lever for this purpose.
Starting with the right side carb bank, open the throttle to raise the slides until the timing dot is completely visible but touching the top of the venturi on one carb only.
Cinch the locknut to hold the adjuster in place.
Raise the adjacent carb slide by turning the adjuster out until the dot position matches the first carb and secure the locknut.
Go to the left side and raise both carb slides to match and cinch the adjusters.
Check the oil pump and adjust the dash marks to line up on the pump body and cable cam.
It helps to use a flashlight to properly illuminate the dot and throttle bore to dispel shadows when positioning the slides for adjustment.
The left side adjusters typically ride about 3 turns higher than the right side. It's just how the cables are cut.
Remember to confirm that the lock nuts are cinched before pulling the rubber cable boots down into place over the cable adjusters.
Operate the throttle to confirm there is no bind or obstruction and that it operates smoothly. For bored carbs, I recommend a richer than stock oil pump setting since the slides are higher when the dots touch the taller venturi.
Rick Lance rick@lancegamma.com (828) 777-4076