Carb floods fuel to airbox - VTX1300S Honda Motorcycles

You need to describe better what you are calling your airbox vent. It sounds like there is a drain hole or port in the airbox to drain away raw fuel that might get in there by flooding. If so it is fuel system overflow or floodign that is causing raw fuel to be in the airbox.

rebuild the carb and check the mounting seals between the carb, air filter and engine. It's probably just gummed up & it's not stopping the gas from free flowing into your airbox.

Check vacuum diagram something has got to b crossed

I am assuming you mean there is an oil slime inside of the airbox just around the #1 carb. could be caused by that cylinder going bad or being weak. you need to do a compression check, check for clean spark and make sure it is getting fuel. any loss of any one of those and that cylinder will give you issues.

hi, this is almost certinly a float valve not closeing,removal of the carbs, careful strip down and clean, only the lower of the carbs must be dismantled for this task, paul

You may need to rebuild the fuel tap with a new diaphram kit.

The fuel tap has a small rubber diaphram and plunger, which can go hard, stick closed , or wear out and get a hole.
Also check the vacumn hose than opperates the tap is in good condition
Pri bypasses the vacumn opperated fuel tap, sometimes this can cause the carbs to flood or have higher than normal float levels..
Running it on prime can also cause the carbs to flood fuel into the engine filling the sump, which then s ucks fuel vapour through the crank breather into the airbox, and then through the carbs causing over rich.
If this has happened you also need to change the oil and fit a new air filter element

floats are stuck allowing fuel to flow . remove carbs and rebuild them slowly you ll need to set float levels too

If your particular model has carbs instead of fuel injection, have the shop clean, balance and syncronize the carbs. Done properly, this will fix the problem.

Please rate this solution. Thanks fvg1!

Hi and welcome to FixYa,

Initially, to your queries:

• hook up all the vacuum lines - yes or cover/plug all
• to stop fuel flow - hooking up all the vacuum lines or covering/plugging them would be technically correct but will not stop the flooding/fuel overflow;
• run correctly - with constant overflow/flooding, it will not run correctly.

To my knowledge, overflow could only be caused by:

• faulty valve pins, worn out rounded pyramids, necked/indentations on the surface of the rounded pyramid, cracks (rubber type);
• worn out inlet port;
• dirt, sand, foreign object lodged against inlet port hole;
• mis-adjusted floats;

Which would mean, go to do it all over again.

Just a start, do postback how things turned up or should you need additional information. Good luck and Thank you for using FixYa.