The Keihin FCR Carb Rebuild With Zip-Ty Racing - Dr. Dirt

19 The throttle shaft rides on two small needle bearings, and they should get a little grease before the shaft is installed. A cotton swab is a good tool for this job.

20 The throttle-return spring has a hook that must engage the throttle shaft before the shaft is reinserted. The shaft washers fit between the body and the throttle-valve lever: the metal one against the carburetor body and the resin washer against the lever.

21 Getting all the throttle-valve parts lined up takes a bit of fiddling, but once they are arranged, the throttle shaft should easily slip through the freshly greased bearings.

22 After setting the plastic spacer in place, use a socket to thread the needle jet/main jet combo into the body. The pilot and starter jets go in next. The threads are brass inside aluminum, so don't go crazy tightening jets.

23 Before the float and needle valve go in, this wire loop attached to the needle must be slipped over this tang on the float. Work over a surface that will allow you to find the float needle if it is dropped.

24 Lower the float and needle valve together. Carefully guide the needle valve into the needle-valve seat. If the tip of the needle bumps the seat, it will pop the wire loop off of the float and cause needless cursing.

25 The manual outlines a method for setting the float height using a caliper. Davis uses a Honda tool that measures the height of the float while lightly blowing into the fuel line.

26 Lift the throttle-slide lever arm out of the way with one hand, and hold the slide (throttle valve) and the throttle-valve plate together with the other hand. Make sure the needle doesn't hang up while going in.

27 The bolt holding the lever arm to the throttle shaft is the only one in the carburetor that calls for thread-locker (blue). Again, you may need a special Torx bit that is drilled to clear the center post.

28 Insert the front float-bowl screws and snug them down, but remember to add the vent hose guides. Then attach and tighten the idle-adjustment screw and bracket.

29 Using your good #2 Phillips, take out the three small screws holding the accelerator-pump diaphragm in place. Detach the cover carefully so you don't lose the spring that rests on the diaphragm.

30 Early FCR carburetors had much poorer accelerator-pump sealing, and the pump membrane could pack with dirt. You can see that only a little dirt has entered this pump and the membrane is in good condition.

31 Replace the diaphragm, spring and cover; tighten the screws; then move to the top of the carburetor body and replace the top. On a Honda, this wire holder goes on the front screw.

32 Before installing the fuel screw in the carburetor body, first slip the spring over the end of the fuel screw, followed by the washer and the O-ring. This Zip-Ty screw comes with the new parts. The rubber covers are separate.

33 With a stock or aftermarket fuel screw, it should take between eight and nine rotations to fully tighten. If you get less than eight turns, don't force it. Check the threads on the screw and in the carburetor body.

34 The stock hot-start fitting has a plastic 14mm hex that is a pain to get a wrench on. Zip-Ty Racing sells a billet-aluminum unit with a 10mm hex. If you haven't already, remove the hot-start plunger and check for corrosion.

35 Zip-Ty Racing also makes a float-bowl drain bolt with a magnet in it. We've tried them, and the magnet nearly always has metal stuck to it. Now install the drain bolt (stock or aftermarket).

36 All that is left is to reattach the vent hoses neatly, and the carburetor is ready to go back on the bike. Now just keep it this clean, and your engine will stay very happy.