T300 Mikuni Carburettor Maintenance
	Reassembling
Home Tools Dismantling Cleaning Inspection Parts Balancing Jetting		For the first carburettor, reinstall the choke needle assembly. Ensure that it is fully seated, and that the retaining lugs are fully secure. Test the mechanism by pulling and releasing the choke pin
		Next, reassemble the pilot air screw assembly. The components should be loaded in this order
		This shows a correctly assembled pilot air screw
		Carefully insert the pilot air screw into the housing, and screw gently all the way until it is fully closed. Based on your tuning records, then REVERSE the screw out the requisite number of “turns out” using half-turn increments
	Note that the screw thread itself is very fine and the metal of the housing is very soft. If you feel ANY undue resistance whilst installing the screw STOP immediately. REMOVE the screw ENTIRELY. Check that there is no dirt on the screw or inside the aperture. If there is, clean thoroughly before attempting to re-install it again. Failure to do so could irretrievably damage the carburettor housing thread
		Next, reassemble the slide guide components shown here
		Here is a correctly assembled slide guide. Note the sealing O-ring secured to its base. The needle jet is installed down through the top of the slide guide hole and sits flush in a recess
	The slide guide must now be lowered into its position from the top of the carburettor. Take careful note of the correct guide orientation, as it will only properly fit one way round.
		Note the sunken brass pin highlighted here. This pin serves to lock the needle jet in its position internally to prevent it spinning when the main jet is screwed in.
		If you look at the lower collar of the needle jet, you will see a milled flat face on one side. This MUST be aligned with the brass pin, otherwise the needle jet will not be able to be seated correctly.
	Therefore when installing the slide guide assembly, particular care must be taken to ensure the needle jet is in the correct orientation to the guide, and that it is lowered in carefully to keep the jet correctly aligned with the pin
		When they are correctly installed, the top of the needle jet will sit flush inside its recess of the slide guide as shown here
		Next, using a large slotted screwdriver, install the main jet. This will also serve to secure the slide guide and needle jet in place
		Then install the pilot jet into the adjacent aperture on the housing, and tighten carefully with a small slotted screwdriver
		Now turn your attention to the float assembly. Install the two sealing O-rings onto the outer frame mounting points
		Turn the outer frame over and fit the float valve into its seat. Position the valve like this
		Gently splay out the sides of the outer frame and feed into it the lower float frame. Seat the two pins into their corresponding pivot holes, and ensure that the metal spring plate is positioned INSIDE the valve wire loop
		Now insert the completed float assembly into the carburettor housing as shown. Note the extended brass tube of the housing goes inside the front mounting post of the float assembly
		Make sure the float assembly is fully seated down in the housing. If it is, then the flat lugs of the assembly base can be seen to be nestling in their recesses as shown here
	It is important that the float assembly is fully seated in order to ensure an accurate adjustment of the float height measurement.
		With the carburettor housing turned upside down, the horizontal edge of the float must be parallel with the mating surface of the housing as shown by the red lines of this picture
	By bending the metal spring plate of the float assembly very slightly up or down, the float position can be adjusted. Each time an adjustment is made, flip the housing over and back to let the float settle in its new position. Check that the float assembly remains in its correctly seated position at both ends in the housing every time a measurement is assessed.
		Next, insert the rubber gasket into the float bowl mating edge, and make sure it is seated into the recessed channel and is fully flat
		Then fit the float bowl back onto the carburettor housing, and secure with the two Phillips screws
		Now fit the diaphragm back onto the slide and ensure that the seating ring is sitting snugly and squarely in the slide’s channelled recess
		If the diaphragm is fitted correctly, it will look like this from the underside of the slide...
		... and appear like this from the top of the slide
		Next, fit the clip to the correct position on the jet needle as per your tuning instructions recorded previously
		Slide the white nylon spacer up the needle to sit flush with the underside of the clip
		Carefully drop the needle down inside the slide recess, so that the needle protrudes out of the bottom through the centre hole
		Then drop the orange spacer down the same recess, to sit squarely on top of the needle as shown here
		Turn the carburettor housing the right way up, and lower the slide assembly down into the plastic slide guide. Make sure that the jet needle drops into the needle jet opening inside the carburettor throat
		With the slide fully inserted, check that the diaphragm’s upper sealing edge is seated snugly and squarely in the circular recess on the top of the housing
		Fit the vacuum take-off sealing O-ring into its recess on the top face of the housing
		Take the carburettor top, and placing it upside down, fit the diaphragm return spring onto the central locating spigot
		Turn over the carburettor top and lower it down onto the top of the housing, ensuring that the lower end of the spring locates correctly into the slide’s central needle recess
	Check that the carburettor top is correctly aligned with the vacuum take-off tube. When the position is verified, fix the top carefully to the housing using the two Phillips screws. Do not over-tighten. Check the top sits uniformly flat on the housing all the way around so that the diaphragm chamber is fully sealed
		To verify that the slide and diaphragm assemblies are installed correctly, you should be able to smoothly lift the slide all the way to the top of the carburettor throat, and when released it should fall back smoothly to its closed position
	Repeat all of the above steps for carburettors two and three
		Next, replace the choke actuator bar, ensuring that it locks into all three choke needle pins correctly, and secure it by sliding the two plastic clips laterally into their restraining lugs. Pull the actuator bar to test the chokes move freely
		Finally, re-attach the idle adjuster bracket to the base of carburettor one using its Phillips screw
Go to Top	The carburettors are now ready to be re-installed on the bike and balanced