Honda CX and GL Carbs and Fuel System
One of the most vexing problems for Honda CX and GL V-twin owners is carb problems – check out our articles for help with not only the carbs but the entire fuel system!
At it’s most basic, the fuel system in the CX and GL bikes is a fuel tank with a manual petcock with a single outlet that leads to the twin CV carburetors. Later models had a vacuum petcock which results in additional tubing, but the basic setup remains the same.
Fuel tank
Small note – GL500 and GL650 tanks are interchangeable in terms of fitment.
- Painting a CX500 Standard/Deluxe tank
- Painting the Standard/Deluxe tank flap
- What tanks fit the CX650ED frame?
- Fitting a CX500 tank to a CX650/GL650/GL500 frame
- Tank alternatives
Petcock
These Hondas came with a petcock with three settings; off, on (or Primary) and reserve. In the above image the petcock is set to "off".
The white tube next to the petcock in the above picture usually sits around the brass tube coming out of the top of the petcock, and functions as a debris screen. It’s not completely effective by any means, and can easily be saturated by rust in the tank – and the little particles which can get through it’s screen are more than large enough to block the circuits inside your carburetor, so an in-line fuel filter does help.
- A closer look at the petcock
- A closer look at the vacuum petcock
- What size petcock do I need?
Fuel sender
A fuel gauge/sender was not a feature on the Custom/Standard/Deluxe models. It was on the CX500E Sports, CX650E Eurosport, CX500T Turbo, CX650T Turbo
Fuel lines
Info to come.
Fuel filters
Airbox/Pod filters
The airbox sits behind the carburetors, and holds the air filter. This is commonly replaced with pod filters on the twisted twins.
Carburetors
All of the CX and GL variants bar the turbo models use carburetors – the turbos use fuel injection.
Stock carbs
The stock carbs are Keihin CV carbs, of varying sizes:
There are two throttle cables in the stock setup, usually referred to as a push cable and a pull cable. One cable (usually referred to as pull) opens the carb butterfly valves by pulling them open against a spring, and the other (usually "push") pulls the butterfly valves closed. While you could theoretically run without the push cable and rely on the spring to close the butterfly valves, should that spring fail you may be unable to close the valves by twisting the throttle back.
A good tip from Murray’s Carbs – when you have the float bowls off blow some compressed air through the overflow tubes or otherwise make sure they’re patent – if the float gets stuck with debris and the tubes are blocked you’re likely to end up with a lot of fuel in your crankcase!
- A closer look at the stock Keihin carburetors.
- How to check the jet sizing on the stock Keihin carburetors
- Carburetor identification numbers – incomplete
- What size pod filters for the stock carbs?
- Removing and cleaning the Keihin float bowls
- Do you need to rejet the carbs if you remove the exhaust H-box?
- Photos showing the different shapes of CX/GL carbs between models
- Location of the sync screws and vacuum ports
Carburetor insulators
Also known as intake runners, intake manifolds etc.
Choke cables
Murray’s Mikuni VM34 Carbs
The most broadly used aftermarket carbs for the twisted twin series.
