How to Clean your Carburetors
Your carbs are responsible for keeping the appropriate fuel to air mixture. The ideal ratio is 14.7 parts air to 1 part fuel. Sounds specific? Good that should give you an idea of how fiddly it can be to work on carbs. That said, getting them in and out is usually the hardest part, the rest is just a bit of trial and error.
You will need
A gasket for your float bowl
Standard hand tools
Carb cleaning process of choice
New jets, needles etc. if you have changed any of the other components on your bike like air filters or exhaust.
Pen and Paper to for adjustment notes
Remove the carbs from the bike by disconnecting The air filters and the the engine block, the fuel line, the choke cable, the throttle cable(s).
Some will say the hardest part of cleaning carbs is getting them in and out of the bike.
Drain your fuel out of the fuel bowl using the drain screws, you can put this fuel back into your tank.
Be sure that you have a fresh gasket before you open up the float bowls. The gaskets or O rings will usually tear when you open them up, without new ones you won’t be able to get the carbs running smoothly again!
Open up each carb very carefully. Refer to an exploded diagram from an owners or shop manual.
Place each nut and bolt in an organized way on your bench, preferably on an old towel to stop them from rolling around or getting damaged. Use dishes to keep things organized and protected
Be sure not to mix up the bolts between the carbs.
As you get into the carb, you will be removing the floats, the float needle, the jets and other of the internal parts of the carbs. These can be placed in a container for each carb to make sure they don’t get mixed up.
If you are only doing a routine cleaning your carbs, as you take out the pilot jets, check to see where they are adjusted to, if your carbs are running well enough before cleaning. You can do this by counting how many turns (and half, and quarter turns) they take to bottom out, and marking it down. You’ll want to set the jets and screws at least close to where they are already.
Proceed to clean the carbs in a number of ways.
- Ultra sonic – this is a process that may take longer, but doesn’t require any chemicals. This process will usually involve taking the carbs to a place that will do this type of cleaning
- Boil clean. Soaking is a great way to clean carbs, and a lot of the time this is sped up by boiling them. Many people will simply use vinegar or even lemon water to boil clean their carbs.
- Chemical Carb Cleaners. These work quickly, and are incredibly toxic. Be sure to follow instructions, use PPE as much as possible and do in a well-ventilated area. You’ll want to soak the carbs in the cleaner in a ceramic vessel, preferably outside.
Carb jets and needles have incredibly small tolerances. Typically you cannot clean these elements mechanically, ie: with a brush or anything abrasive, as that can change their tolerances and can cause the carbs to function differently. You may want to replace the jets and needles with new ones. This way you know that they are 100% clean and functioning properly, to remove any question of where a failure is coming from if you continue to have problems after cleaning.
Re-assemble the carbs in the reverse order that you took them apart in.
Get ready for the fun part of getting them back in!
Careful with your boots when getting the carbs back in, you want to make sure that there aren’t any air-leaks or cracks in these that will throw off your ratio or allow un-filtered air into your carbs.
Follow your shop manual to adjust your needles and pilot screws. Typically this will involve bottoming-out (screwing all the way in) the screw and then turning them back the appropriate amount for your bike’s set up. Good shop manuals will have the stock settings. If not you can check on forums to see what level others have had success with and go from there. Altitude and humidity can affect these adjustments, as well as the general wear and other components on your bike, so you may have to work with this a fair bit to get the carbs well tuned. What one person has adjusted to is a good starting point, but you’ll have to play with it yourself to get it right for your bike.
For a great diagram of how a Carburetor works, check out this video
And a great in-depth video of how to change your carb adjustment (jets and needles) if you’re changing any of your components like air filters and exhaust check out here.