How to Rebuild a Yamaha F255 Outboard Part 2: Powerhead Teardown

Having removed the electrical system, fuel system and ancillaries from our Yamaha F225TXRC outboard, it's time to strip the powerhead before completely rebuilding it. 

This guide is a companion to our Yamaha F225TXRC Outboard Rebuild Part 2 video above, which shows you precisely how to tear down the powerhead. The steps covered include how to remove:

  • Cam gears and belt
  • Exhaust and cylinder head covers
  • Camshafts
  • Cylinder heads
  • Valves

Watch the Yamaha F225 outboard rebuild video above and print out this guide to use as a reference while you work through each step. Use our Yamaha F225TXRC outboard parts diagrams for reference to see how all the components come apart and fit back together again.

Yamaha F225 outboard rebuild powerhead teardown

Tools Needed - Yamaha F225 Outboard Powerhead Removal

  • Ratchet and extensions
  • Socket set
  • Allen set
  • Torx set
  • Screwdriver

PRO TIP: Collect the nuts, bolts, screws, washers, etc. from each component as you remove them, put them in a zip-lock bag and label the bag. It'll be much easier to find the correct part for the correct component when the time comes to reassemble the motor.

Tearing Down a Yamaha F255TXRC Powerhead

NOTE: Although an impact wrench is fine for disassembling an outboard, it should never be used to reassemble one, as it is too powerful and will easily strip threads or shear bolts.

Step 1. Release the tensioner assembly. Use a 10mm Allen and slowly rotate the tensioner to release tension on the belt. Hold the tensioner in place with a punch (or similar tool), and slide the belt off the drive gear and driven gears. Remove the tensioner completely.

Yamaha F225 outboard belt tensioner

Watch the clip below to see the tensioner assembly removal segment of our Yamaha F225TXRC powerhead teardown video.

Step 2. Remove the cam driven gears and drive gear. Use an impact wrench and hold the cam gears to prevent them from turning as you remove them. If the gears are allowed to turn, they will bend the valves.

Yamaha F225 outboard cam gear removal

Watch the clip below to see the cam gears removal segment of our Yamaha F225TXRC powerhead teardown video.

Step 3. Remove the ground cable that runs between the two cylinder heads.

Yamaha F225 outboard cylinder heads

Watch the clip below to see the ground cable removal segment of our Yamaha F225TXRC powerhead teardown video.

Step 4. Remove the exhaust outer covers. The two exhaust covers are numbered to show the tightening sequence for the 14 bolts in each. To remove the covers, loosen the bolts in the reverse number sequence from 14 to 1. Once the bolts are removed, insert a screwdriver into the pry points at the bottom of the covers and pry them free from the crankcase, being careful not to damage the mating surfaces of the covers or the crankcase.

Yamaha F225 outboard rebuild powerhead

Step 5. Remove the cylinder head covers and the cam chain tensioners.

Watch the clip below to see the exhaust and cylinder head cover removal segment of our Yamaha F225TXRC powerhead teardown video.

Step 6. Remove the port side camshafts. Remove the four cam caps on each camshaft in the sequence shown in the image below. Once the camshafts are removed, clean and number the tappets so you can reinstall them in the same place, and then remove them using a magnet.

Yamaha F225 outboard camshaft removal

Watch the clip below to see the port side camshafts removal segment of our Yamaha F225TXRC powerhead teardown video.

Step 7. Remove the port side cylinder head. Remove the eleven cylinder head bolts in the sequence shown in the image below.

Yamaha F225 outboard rebuild port cylinder head

Watch the clip below to see the port side cylinder head removal segment of our Yamaha F225TXRC powerhead teardown video.

Step 8. Remove the starboard side camshafts. Remove the five cam caps on each camshaft in the sequence shown in the image below. Once the camshafts are removed, clean and number the tappets so you can reinstall them in the same place when you rebuild the cylinders. Remove the tappets using a magnet.

Yamaha outboard motor powerhead removal

Watch the clip below to see the starboard side camshafts removal segment of our Yamaha F225TXRC powerhead teardown video.

Step 9. Remove the starboard side cylinder head. Remove the eleven cylinder head bolts in the sequence shown in the image below.

Yamaha F225 TXRC outboard rebuild

Watch the clip below to see the starboard side cylinder head removal segment of our Yamaha F225TXRC powerhead teardown video.

Step 10. Remove the valves. You'll need to use a valve spring compressor to remove the valves. If you intend on reusing the valves, clean and number them so you can reinstall them in the same place when you rebuild the cylinders.

Yamaha F225 outboard engine valves

Watch the clip below to see the valve removal segment of our Yamaha F225TXRC powerhead teardown video.

Now that the top end of your Yamaha F225 outboard disassembled, the pistons and crankshaft are next. Watch our Yamaha F225TXRC Outboard Part 3 video below to see how to tear down the bottom end of your motor.

Qty.

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