1988-1994 Honda TRX300 Fourtrax, 1988, 1990-1994 TRX300FW Fourtrax Service Manual, Page 62Get this manual
FUEL SYSTEM DIAPHRAGMV ACUUM PISTON Install the needle clip on the jet needleSTANDARD SETTING: 3rd groove from the top (2) CLIP
(1) JET NEEDLE
Install the washer, jet needle, spring and jet needle holder to the vacuum pistonPush the jet needle holder in and turn it 90 degrees clockwise
(1) WASHER (2) SPRING
{(4) JET NEEDLE
Install the diaphragmpiston in the vacuum chamber, aligning the diaphragm tab with the groove of the carburetorHold the vacuum piston up to almost full open so the diaphragm is not pinched by the chamber coverInstall the chamber cover with the spring, aligning its tab with the hole in the carburetor, and secure with at least two screws before releasing the vacuum piston(2) SPRING DIAPHRAGM VACUUM PISTON