Yamaha F255 Outboard Rebuild Part 5: Top End

After rebuilding the bottom end of our Yamaha F225 outboard, it’s time to rebuild the top end. 

This guide is a companion to our Yamaha F225TXRC Outboard Rebuild Part 5 video, which shows you how to install the cylinder head assembly into the motor. 

Watch the Yamaha F225TXRC Outboard Rebuild Part 5 video above and follow the walkthrough below to rebuild an F225 engine. Use our Yamaha F225TXRC outboard parts diagrams for additional reference.

Tools and Parts Needed – Yamaha F225 Top End Rebuild

Tools

  • Torque wrench capable of measuring angles

NOTE: Aside from the tools and parts listed above, you’ll need a well-stocked toolbox that includes a ratchet and socket set, Allen set, wrenches, screwdrivers, pliers, etc. If your F225 is in relatively good condition, you may be able to get the cylinder heads resurfaced at a machine shop. However, we’re completely replacing the top end with brand new Yamaha F225TXRC cylinder head assemblies. 

Yamaha F225 outboard rebuild top end

Disassembling Yamaha F225TXRC Cylinder Head

NOTE: If you’re installing new Yamaha F225 cylinder head assemblies, you must first remove the cam tensioners and the camshafts. 

Step 1. Remove the cam chain tensioner assembly, followed by the four cam caps on each camshaft from the port cylinder head in the sequence shown in the image below, before removing the camshaft.

Yamaha F225 outboard cylinder head

Step 2. Remove the cam chain tensioner assembly, followed by the five cam caps on each camshaft from the starboard cylinder head in the sequence shown in the image below, before removing the camshaft.

Yamaha F225 outboard engine rebuild

Watch the clip below to see the cylinder head disassembly segment of our Yamaha F225TXRC bottom end rebuild video.

Installing Yamaha F225TXRC Cylinder Head (Port Side)

Step 1. Install the water shut grommet and dowel pins into the crankcase, and make sure the crankshaft is in the correct position by aligning the timing belt drive gear with the mark on the crankcase.

Yamaha outboard engine crankcase timing

Step 2. Clean the crankcase mounting surface with contact/brake cleaner, then install a new cylinder head gasket and the cylinder head onto the crankcase.

Step 3. Oil the cylinder head bolts, then tighten and torque them in the sequence shown in the image below.

Yamaha F225TXRC top end rebuild

1. Torque bolts 1-8 to 14 foot-pounds

2. Torque bolts 1-8 to 27 foot-pounds

3. Torque bolts 1-8 an additional 90-degrees

4. Torque bolts 9-11 to 10 foot-pounds

5. Torque bolts 9-11 to 20 foot-pounds

Watch the clip below to see the port cylinder head segment of our Yamaha F225TXRC bottom end rebuild video.

Installing Yamaha F225TXRC Camshafts (Port Side)

Step 1. Apply assembly lube to the valve lifters and surfaces the camshafts will rest on, then install the port camshafts into the cylinder head, and lightly oil and install the camshaft oil seal.

Step 2. Install the camshaft caps, and tighten and torque them in the sequence shown in the image below.

Yamaha F225 outboard camshafts

1. Torque the bolts to 5.8 foot-pounds

2. Torque the bolts 12 foot-pounds

Step 3. Install the cam chain tensioner assembly, and torque its mounting bolts to 8.7 foot-pounds. Remove the retaining pin if it’s still in the tensioner.

Watch the clip below to see the port camshafts segment of our Yamaha F225TXRC bottom end rebuild video.

Installing Yamaha F225TXRC Cylinder Head (Starboard Side)

Step 1. Install the water shut grommet and dowel pins into the crankcase, and make sure the crankshaft is in the correct position by aligning the timing belt drive gear with the mark on the crankcase.

Step 2. Clean the crankcase mounting surface with contact/brake cleaner, then install a new cylinder head gasket and cylinder head onto the crankcase.

Step 3. Oil the cylinder head bolts, then tighten and torque them in the sequence shown in the image below.

Yamaha F225TXRC top end rebuild cylinder head

1. Torque bolts 1-8 to 14 foot-pounds

2. Torque bolts 1-8 to 27 foot-pounds

3. Torque bolts 1-8 an additional 90-degrees

4. Torque bolts 9-11 to 10 foot-pounds

5. Torque bolts 9-11 to 20 foot-pounds

Watch the clip below to see the starboard cylinder head segment of our Yamaha F225TXRC bottom end rebuild video.

Installing Yamaha F225TXRC Camshafts (Starboard Side)

Step 1. Apply assembly lube to the valve lifters and the surfaces the camshafts will rest on, then install the starboard camshafts into the cylinder head, and lightly oil and install the camshaft oil seal.

Step 2. Install the camshaft caps, and tighten and torque them in the sequence shown in the image below.

Yamaha F225 outboard motor top end rebuild

1. Torque the bolts to 5.8 foot-pounds

2. Torque the bolts 12 foot-pounds

Step 3. Install the cam chain tensioner assembly, and torque its mounting bolts to 8.7 foot-pounds. Remove the retaining pin if it’s still in the tensioner.

Watch the clip below to see the starboard camshafts segment of our Yamaha F225TXRC bottom end rebuild video.

Installing Yamaha F225TXRC Cylinder Head Covers

Step 1. Install new cylinder head cover gaskets into the cylinder head covers, and apply Yamabond to the areas shown in the image below.

Yamaha F225 outboard cylinder head installation

Step 2. Install the cylinder head covers onto the motor, then use blue threadlocker on the cover bolts and tighten them down.

Watch the clip below to see the cylinder head covers segment of our Yamaha F225TXRC bottom end rebuild video.

With the top end of our Yamaha F225 rebuilt, the next process is working on rebuilding the timing and electrical systems. Watch our Yamaha F225TXRC Outboard Part 6 video below to see how to get that done.

 

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