How to Rebuild a Yamaha F225 Powerhead

Turning a workbench full of Yamaha outboard bits and bolts into a fully functioning outboard motor can seem like a daunting task.

Searching through a video while you’ve got a wrench in one hand and an integral outboard part in the other isn’t easy, so we’ve come up with this Yamaha F225 powerhead rebuild guide. Watch the video above and follow the steps below to rebuild a Yamaha F225 outboard engine powerhead.

NOTE: The list of parts to rebuild a Yamaha F225TXRC powerhead can be found here.

Yamaha F225 Crankcase Assembly

Step 1. Size the crankshaft bearings. Jot down the bearing numbers on the crankcase and the crankshaft, and compare them to a bearing chart to determine the correct bearings.

Watch the clip below to see the bearing sizing segment of our Yamaha F225TXRC Powerhead Rebuild video.

Step 2. Measure the crankshaft bearing clearances.

Step 3. Install, clean and lube the crankcase bearings and the crankshaft, then apply sealant to the face of the crankcase and assemble the two halves of the crankcase. Torque the bolts in the sequence and to the torque settings shown in the diagram below.

Step 4. Install the oil pump.

Watch the clip below to see the crankcase assembly segment of our Yamaha F225TXRC Powerhead Rebuild video.

Yamaha F225 Piston Installation

Step 5. Install the connecting rods to the pistons and measure the connecting rod bearing clearances.

Step 6. Measure the piston ring gaps and install the piston rings onto the pistons.

Step 7. Clean and lube the piston/connecting rod assemblies and install them into the cylinders.

Watch the clip below to see the piston/connecting rod assembly and installation segment of our Yamaha F225TXRC Powerhead Rebuild video.

Yamaha F225 Oil and Cooling Systems Installation

Step 8. Install the crankcase cover.

Step 9. Install the oil system and the cooling system. These include installing the oil baffle plate, oil filter housing, oil filler neck, water hoses, thermostats and cooling passage cover.

Step 10. Install the timing belt drive gear.

Watch the clip below to see the oil and cooling system installation segment of our Yamaha F225TXRC Powerhead Rebuild video.

Yamaha F225 Cylinder Head Assembly

Step 11. Install the cylinder head gaskets and cylinder heads.

Step 12. Torque the starboard-side cylinder head bolts in the sequence shown in the image below. First, torque each bolt to 14 foot-pounds, then torque each bolt to 27 foot-pounds, and then torque each bolt by an additional 90-degree turn.

Step 13. Lube and install the camshafts, cam chain and cam chain tensioner.

Step 14. Torque the starboard-side camshaft cap bolts in the sequence shown in the image above. First, torque each bolt to 5.8 foot-pounds, then torque each bolt to 12 foot-pounds.

Step 15. Torque the port-side cylinder head bolts in the sequence shown in the image below. First, torque each bolt to 14 foot-pounds, then torque each bolt to 27 foot-pounds, and then torque each bolt by an additional 90-degree turn.

Step 16. Lube and install the camshafts, cam chain and cam chain tensioner.

Step 17. Torque the port-side camshaft cap bolts in the sequence shown in the image above. First torque each bolt to 5.8 foot-pounds, then torque each bolt to 12 foot-pounds.

Step 18. Install the cylinder head covers.

Watch the clip below to see the cylinder head assembly segment of our Yamaha F225TXRC Powerhead Rebuild video.

Yamaha F225 Camshaft Gears and Flywheel Installation

Step 19. Install the camshaft timing gears.

Step 20. Install the throttle linkages, the timing belt and timing belt tensioner and the stator.

Step 21. Install the flywheel and torque it to 174 foot-pounds using a flywheel holder to prevent the flywheel from rotating. Next, install the throttle arm.

Watch the clip below to see the cam gears and flywheel installation segment of our Yamaha F225TXRC Powerhead Rebuild video.

Yamaha F225 Electrical System Installation

Step 22. Install the thermostats and the regulator/rectifier assembly.

Step 23. Install the wiring harness and the starter motor.

Step 24. Install the ignition coil bracket and the spark plugs, then reconnect the spark plug cables.

Watch the clip below to see the electrical system installation segment of our Yamaha F225TXRC Powerhead Rebuild video.

Yamaha F225 Fuel System Installation

NOTE: As part of our Yamaha F225 Powerhead Rebuild video, we disassembled and serviced the vapor separator tank. If the VST on your outboard is in good working order, skip to Step 25.

Watch the clip below to see the VST service segment of our Yamaha F225TXRC Powerhead Rebuild video.

Step 25. Install the VST.

Step 26. Check the hoses and replace any that are split or worn. Also, make sure all the hose clamps are tight and replace any that are worn. Install the hoses and clamps.

Watch the clip below to see the fuel system installation segment of our Yamaha F225TXRC Powerhead Rebuild video.

NOTE: As part of our Yamaha F225 Powerhead Rebuild video, we cleaned and serviced the fuel injectors. If the fuel injectors on your outboard are in good working order, skip to Step 27.

Watch the clip below to see the fuel injector service segment of our Yamaha F225TXRC Powerhead Rebuild video.

Step 27. Install the throttle body assemblies to the cylinder heads.

Step 28. Connect all the electrical connections to the fuel system and connect the throttle linkage.

Step 29. Join the two intake silencers into a single assembly and install the assembly onto the throttle body assemblies.

Step 30. Reinstall the flywheel cover to the top of the motor and you’re done.

Watch the clip below to see the fuel system installation segment of our Yamaha F225TXRC Powerhead Rebuild video.