To replace the cam chain on a 2005 Honda TRX650FA, follow these general steps:

Tools and Parts Needed:
- Replacement cam chain
- Basic hand tools (sockets, wrenches, screwdrivers)
- Torque wrench
- Flywheel puller
- Gasket set
- Service manual (recommended for torque specs and timing)

Procedure:

1. Preparation:
- Disconnect the battery.
- Remove body panels, seat, and fuel tank for access.
- Drain engine oil and coolant.

2. Engine Disassembly:
- Remove the front engine covers, recoil starter, and timing inspection covers.
- Remove valve covers and spark plug.
- Set the engine to Top Dead Center (TDC) on the compression stroke using timing marks on the flywheel.

3. Remove Components:
- Remove the camshaft sprocket bolts and the sprocket (mark chain and sprocket for alignment).
- Remove the timing chain tensioner.
- Remove the cylinder head cover and camshaft.
- If needed, remove the flywheel and side cover to access the lower end of the cam chain.

4. Replace Cam Chain:
- Remove the old cam chain.
- Install the new chain, routing it over the crankshaft sprocket and up to the camshaft.
- Ensure the timing marks on the camshaft and crankshaft are aligned properly.

5. Reassembly:
- Reinstall camshaft, sprocket, and tensioner.
- Torque all bolts to spec.
- Reinstall cylinder head cover, side covers, and all removed components.
- Refill engine oil and coolant.

6. Final Steps:
- Rotate engine manually to ensure proper timing.
- Reconnect battery and test start the engine.
- Check for leaks and unusual noises.

Note: Accurate timing and torque specs are critical. Use a service manual specific to the 2005 Honda TRX650FA for details.