After many years of great service, I noticed that I had to keep the choke part way open in order to keep my 1998 Honda CBR600F3 running at idle when warmed up. This happened after the 6-month hibernation my motorcycle took over the winter months here in Ohio. I was surprised, given that I always fill the tank with fresh fuel and add Sta-Bil fuel stabilizer prior to putting the motorcycle away for winter. Apparently it was time to take the carburetors off the motorcycle and give them a good cleaning!
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Step 1: Drain Fuel from Carburetors
The first thing you must do is drain as much fuel from the carburetor float bowls a possible. This will reduce fuel spillage during the carburetor removal process. In a well ventilated area, start the motorcycle, then let run until warm. Now turn the fuel petcock to the off position and let run until the motorcycle is starved for fuel and dies. Then turn off the motorcycle. Leave the fuel petcock in the off position.
Step 2: Remove Side Covers and Seat
You need to get at the carburetors in order to be able to clean them! The first step is to remove the side covers and seat. The side covers are held in place by several fasteners and locking mechanisms. To unlock them, use a screwdriver to change the position of the locking mechanism. Pull the side covers straight off. Two bolts keep the seat in place (circled in red above), one on each side of the bike. Unbolt, then pull the seat up and back to remove.
Step 3: Remove the Battery
Step 4: Remove the Gas Tank
Make sure the fuel petcock is in the off position before proceeding!
Step 5: Remove the Air Cleaner
Step 6: Remove Carburetors from Motorcycle
You will remove all four carburetors from the motorcycle as one unit.
Step 7: Disassemble Each Carburetor
Important Note: Work on the carburetors in a well-ventilated area, free from possible ignition sources.
Put some rags down on your bench, as the carburetors may leak some fuel during the disassembly process.
The photos below show only one carburetor being disassembled: you must do these steps for each one.
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It is important to keep the parts for each carburetor separate from the others. Parts from carburetor one should be re-installed on this carburetor once the cleaning process is complete. Do not mix carburetor parts, doing so will affect the performance of the motorcycle. I label each carburetor 1 through 4, and label bins 1 through 4 to hold all the parts for a specific carburetor.
Step 8: Clean All the Parts
Finally, all four carburetors should be disassembled. Now it is time to clean all of the parts.
First, I purchase four cans of Gumout Carb and Choke Cleaner Jet Spray. I then set up a table outside to perform the cleaning process. The carburetor cleaner fumes can be noxious so it is important to work in a well-ventilated area.
Safety First! Wear eye protection (I wear these goggles) so that you do not accidentally get carburetor cleaner splashed in your eyes and keep your mouth closed as it is probably not a good idea to swallow it. I also wear heavy-duty chemical-resistant gloves as the carburetor cleaner does a wonderful job of drying out your skin and nail cuticles.
I then bring the carburetor assembly out in a clean oil drain pan and start up the old air compressor. I use the air compressor to thoroughly dry each part after it have been sprayed with carburetor cleaner. Finally, I use aerosol can tops as small soaking tanks for the discrete parts removed from the carburetors.
Step 9: Clean the Carburetor Passages
I connect the small tube that comes with the carburetor cleaner to the nozzle, then systematically spray into each orifice where the jets and idle mixture screw were removed. It is important that each of these passages be clean of debris, varnish, and carbon. You will know when a passage is clear because you will see carburetor cleaner come out of the other end. If you look down the throat of the carburetor, you will see small pin-size holes next to the throttle butterfly valves. It is important that these holes also be clear and free from debris if you want your motorcycle to perform properly!
Step 10: Repeat Cleaning
I give each carburetor body several thorough cleanings with spray carburetor cleaner, then dry them off with the air compressor shooting air into each orifice, inspect, then repeat the process. Don't waste the carburetor cleaner by spraying down the complete carburetor body: focus on the internal passages that are actually involved in the fuel-air mixing process.
Step 11: Clean the Discrete Parts
Remember: keep the discrete parts—all of the little parts that you took off of the carburetor body—from each carburetor segregated. For best performance, you want to install the parts onto the carburetor body that you removed them from.
For cleaning these small parts, I turn aerosol can tops upside down to serve as mini soaking tanks, place all of the parts in the tops, and then spray carburetor cleaner into the top. I let the parts soak for about fifteen minutes, then use needle-nose pliers to extract each part from my mini soak tank. I let them air-dry on a clear shop rag.
Because the floats are too big to fit in the aerosol can top, I just spray them down with carburetor cleaner.
Step 12: Inspect the Discrete Parts
Each jet has a tiny precision hole drilled down the center to properly meter the right amount of fuel. It is important that these holes be clear and free of debris, carbon, or varnish. If the hole is blocked, try to open it up by spraying some carburetor cleaner through the hole. Do not try to remove the blockage by mechanical means like using a wire; this can alter the performance of the jet. Some jets are tiny cylinders with a number of holes drilled on the side; make sure these tiny holes are clean as well.
Step 13 Assembly
The assembly process is the opposite of the disassembly process. Just read from the bottom of the lens to the top and you will have those carburetors attached to the intake manifold and back in the bike in no time. Remember, that you need to install the discrete parts in the same carburetor you remove them from.
Cleaning the carburetors on a CBR600F3 is a snap if you pay attention and keep organized.
This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.