2005-2009 Honda TRX400EX/TRX400X Service Manual, Page 80Get this manual
LUBRICATION SYSTEM OIL PIPES
Disconnect the il pipes from the oil tank (page 5-9) and oil cooler (page 5-9) Remove the following- jOint bo lts oil pipes (remove the engine-la -o il coo ler pipe from the clamp)
Replace rhe O-rings iT new ones and eoa! lh wnh engm oil