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Project CB 750

Carburetor Rebuild & Cleaning

After Before (can you believe it?)

Started on Carbs Removing Main Jet  Cleaning Primary Jet Cleaning Main Jet
That's a picture of the #1 carb after I cleaned it and the #2 carb BEFORE cleaning! I remove the main jet with an 8mm open-end wrench I try my best to blast a shot or two of cleaner through each jet Here I'm blasting the main jet.
Cleaning Needle Jet Blowing Air through jets

I'm sticking the carburetor cleaner tube up the needle jet holder to spray cleaner up the opening After I've cleaned everything the best I can, I spray clean air (for cleaning computers) through it all. Shot of one of the slide valves and needle before cleaning the needle off with fine steel wool.


Wow!  You've got to see these things to believe it.  I've NEVER seen carburetors so gunked up.  Check out some of the pictures I have by clicking on the thumbnails above.  Here's how I cleaned them:

  1. Get the carburetors off the bike.  I did this by loosening all of the screws that held the rubber boots to the air box (on the intake side) and the engine head (on the downstream side of the carburetors).  I also had to remove both the throttle open and throttle close cables.  Lastly, I removed the two fuel lines that were connected to the fuel tank (I removed them AT the fuel tank).
  2. Remove the float bowls. (See 7/31 picture) This was as simple as taking a screwdriver and prying the metal clip upwards.  Once that was done, I took the butt end of a screwdriver and lightly tapped the bowl until it loosened.  Then I carefully removed the bowl to expose the "meat" of the carburetors.
  3. Clean the jets (see the 8/31 pictures)  Lots-a-work here.  As you can see from the 7/31 picture above left, there was a LOT of "varnish" on the jets.  They were 100% plugged.  The entire contents of the bowl were COVERED with a crusty layer of varnish.  I removed as much as I could with my fingers and a small flat-blade screwdriver (only on the non-jet parts).  The jets I let soak overnight in a bath of carburetor cleaner.  After soaking, I took an old toothbrush and cleaned them all off.  I carefully stuck a piece of wire I knew to be smaller than the jet opening up the jet to be sure it was clear.  I then soaked them some more and forcibly blew some carburetor cleaner through them.  I also soaked a few Q-tips in cleaner and cleaned out anything I could.  After cleaning out the jets, I would hold them up to the light to see if I could "see the light" through them.  
  4. Clean everything else Obviously, pretty much everything needed to be cleaned.  Most of the cleaning was done with either a Q-tip or a toothbrush.  Basically EVERYTHING got disassembled (I only did ONE carburetor at a time in its entirety though!)
  5. Polishing  Ahhhh, the finishing touch.  I took some fine steel wool to the exterior of each of the bowls and the part of the carburetor bodies that I could get at.  (I DON'T polish the chrome - only the aluminum). The steel wool helps to knock off most of the major oxidation (fancy word for rust).  After the steel wool, I took each of the bowls to the bench polishing wheel for the finishing buff and coat of protection.  At this point, I could spray a protective aluminum coating (like Nyalic) on, but I've found the shine is better without it...and the protection it adds isn't that important if the bike is garage kept and loved).
  6. Reassemble  When putting everything back together, I check for proper alignment, good gaskets, no binding, and a good fit.  Where appropriate, I use a bit of fuel-proof gasket sealant for sealing.  I also checked to see that all of the floats closed the needle valve completely without forcing.  

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(Electrical Work)


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Last Update: Wednesday, December 14, 2005 11:53 PM