How to clean MOTORCYCLE carburetors, thoroughly!

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To properly clean our carburetors we need to remove
- Our trumpets / velocity stacks
- Throttle slide, needle and diaphragm assembly
- Our main jets, needle jet holders (emulsion tubes) and pilot jets
- Our pilot screws
- Air cut off valves
- Choke valves

To remove all this we are going to need to separate the carburetors

Before we start removing things we need to freest drain the fuel using the little fuel drain screws at the bottom of the float bowls. Attach a hose to the drain and drain away the fuel. This will make the removal easier and avoid any fuel spilling around.

The first thing I usually remove are the top covers. Underneath them are the throttle slides, needles springs and diaphragms.After that you can remove the float bowl covers. These are also held in by three bolts each and are easy to remove. Next up we are going to remove the velocity stacks. Also, easy. just a bunch of bolts to be unscrwed.

After that we remove all our choke valves. We have a total of 4 on the CBR600 carbs and the bracket which activates them is held in by two bolts. Once the bracket and return springs are off its time to remove the choke valves themselves. You can easily do this with a simple wrench.

Now we are going to start to separate the carbs. To do this we need to remove the nuts which are at the ends of the two long rods that hold the carbs together. Once the nuts are off you can slide out the rods and separate the carbs. The carbs often won't come apart that easily and might need a bit of help. Be gentle here.

Once you have separated the carbs, mark which one is which so you don't mix them up.

After this we are going to remove our pilot screws, main jets, our pilot jets and our needle jet holders (emulsion tubes).
Now that the carbs have been separated we also have access and can remove all four of the air cut off valves.

Clogged pilot jets are the number one reason for a no start condition on a carbureted engine. In the video you can see a clogged pilot jet and a clean one. As well as a side by side video of one that's a about to get clogged and a clean one.
Clogged pilot jets mean that not enough fuel will be getting into the combustion chamber and the engine won't start, or will run poorly in case the internal diameter of the jet has been reduced by contaminants.

After you have removed everything and taken it apart you can clean the carbs. I like to spray everything and every orifice with carb cleaner and then blow it all out with a lot of compressed air.
If needed soak all the bits in carb cleaner overnight. Also inspect everything for damage or unusual wear and replace as needed.
Inspect all the gaskets and replace as needed. I like to give all the rubber gaskets and o rings some silicone spray to refresh them and make sure the rubber stays nice and flexible.
After that put everything back in its place and reinstall. After a cleaning procedure that is this detailed you will need to readjust your pilot screws and balance the carburetors.

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