2005-2008 Honda ATV TRX500FA/FGA Fourtrax, Rubicon Factory Service Manual, Page 128Get this manual
FUEL SYSTEM Be careful not to damage the jet needle
Install the diaphragmvacuum piston into the carburetor body by aligning the tab of the diaphragm with the air passage, then insert the jet needle into the needle jetLift the bottom of the piston with your finger to set the diaphragm rib into the groove in the carburetor body
DIAPHRAGM PISTON
TAB AND AIR PASSAGE
Be careful not to pinch the diaphragm under the chamber cover, and to keep the spring straight when compressing the spring
Install the compression spring and vacuum chamber cover while lifting the piston in placeAlign the tab of the cover with the air passage and secure the cover with at least two screws before releasing the vacuum pistonVACUUM CHAMBER COVER