Even though your Yamaha WaveRunner XLT 800 is a personal watercraft, to be used in the great outdoors, a leaky exhaust gasket will leave you riding the waves in a stinking miasma of exhaust gas. The gasket, positioned between the WaveRunner’s exhaust chamber and its muffler, is reached easily enough, since the muffler and exhaust chamber can be moved apart without further disassembly.
1) Remove the four 10 x 65 mm bolts that secure the rear of the manifold to the engine block, using a 10 mm socket, a ratchet and a 6-inch extender.
2) Remove the four 10 x 125 mm bolts that secure the front of the exhaust manifold to the forward end of the engine block.
3) Move the wiring harness brackets — held in place by the two 10 x 125 mm bolts that hold the manifold to the forward end of the engine block — away from the engine. Remove the gasket.
4) Scrape any gasket material or gasket compound from the mating surfaces of the manifold and engine block, using a plastic scraper.
5) Spread a thin layer of gasket sealing compound on both sides of a new exhaust manifold gasket. Place the gasket over the two alignment pins on the block.
6) Position the exhaust manifold on the alignment pins. Thread the four 10 x 65 mm bolts into the bores at the rear of the manifold first, followed by the 10 x 125 mm bolts at the forward end of the manifold. Tighten the bolts to 17 foot-pounds in a crisscross pattern, using a torque wrench.
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