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FAQ FUEL: Q. What octane? A: These bikes run fine on 87 octane.

Q. Which way do I turn the idle mixture screws under the carb to richen the idle mixture? A. These control fuel to the idle circuit, so turning them inward will lean the mixture, turning them out richens the mix. 2-1/2 turns out from a light seat is a good starting point when adjusting.


Q. What size is the Fuel Hose? A. 1/4" for CX500 7mm for the GL series (inside dimensions)

Q. I don't have a reserve working on my petcock, what's wrong? A. There is a short (2") plastic tube attached to one port of the petcock inside the tank. This has either been removed or is missing.

Q. I can't turn my idle mixture screws even a full turn, how can I adjust them? A. These screws have factory caps on them with tabs to prevent large adjustments to the rich side. Some file the tabs off, some grind a notch in the stop that is cast into the float bowl. These were originally mandated by emission laws.

Q. What is a Vacuum Petcock? A. Some later models employ a petcock that requires engine vacuum to allow fuel to flow. This was designed as a safety feature, but as the rubber parts age, this feature becomes troublesome, the cause of some runnability issues, and is sometimes bypassed. The petcock uses a vacuum hose from the front port on the petcock to a vacuum pipe on the right carb. Center port is open to air.

Q. There is a small brass pipe coming out of the carbs above the float bowl, what attaches there? A. These are atmospheric vents for the carb float bowls and should be verified as clear and no hoses get attached to them.

Q. I keep hearing about this Larry fellow that works on carbs, who is he and how do I contact him? A. Larry goes under the screen name LRCXed on the forum. He has literally written a book on carb cleaning and can be contacted by PM in the Members section of the forum. Or direct e-mail, [[1]]

Q. Any idea what Larry charges for a carb rebuild? A. It is best to contact him directly as costs vary by each job. As a general ballpark it is less than $300.00, which includes all new expendable parts, complete deep ultrasonic cleaning, exterior cleanup and polishing, all passageways verified open, and both bench and on bike testing. Typically, if one is just going to clean their own carbs once, having Larry clean them may be the better solution.

Q. What are these black rubber plugs in the float bowls of my carbs? A. Those rubber plugs are called blanking plugs. They cover the access to idle fuel jets. More information can be found here. Randakk's Cycle Shakk (be aware there are different sizes of plugs used through the years/models)


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