leaking head gasket

yamahog · Posted: June 7, 2005, 11:07 am Post subject: leaking head gasket

I've always had problems with my head gaskets leaking. I've even replaced them several times with several engines and they still leak. Any ideas would be great!!

Jack · Full Member Joined: Mar 15, 2005 Posts: 411

Yamahog, I'd double check the camshaft seals and the rocker arm section gasket, as these are some possible areas to easily overlook. For the heads itself,its possible the leakage is due to some slight head surface being warpt and resurfacing the gasket surface is the only solution here,along with a good permatex gasket sealer like Permatex 93,Mega Copper bond and #2 form a bond.These are sealers that don't harden and should provide an excellent seal. Another good product that I've great success with is a product called ThermaBond Liquid Gasket 1104. These sealers are to be used along with the regular head gasket. This seems to be a common problem with the XS,so keep us posted as to what means you found to remedy the problem. Also don't forget to retorque the cylinder head nuts after a few cool dowm periods as these will loosen up due to expansion......Jack

grizld1 · Posted: June 20, 2005, 3:26 pm Post subject: Re: leaking head gasket

If your head's good--i.e. unwarped--the problem's probably the usual grief occasioned by the construction of the XS650 engine. Note that unlike most large 4-stroke twins, there are no separate cylinder mounting bolts. Everything from the cylinders to the head cover mounts on a set of long, long, stretchy, sticky studs! Two-stroke construction strikes in the night! (In the early XS1, Yamaha even put caged needle bearings at the wristpins, if you can believe it--but not for long, since the heavy power pulses of the big 4-stroke tore 'em up fast!)

The cure is progressive retorquing as everything resettles. Torque the head cover to spec. and let it sit overnight. Bring it to spec again in the morning. Repeat till STAYS at spec. Warm it up at idle, cool it down, and retorque. Ride it till it warms up thoroughly, take it back to the barn, let it cool, and retorque. Do it again at 500 miles. Then check it annually.

yamahog · Posted: June 24, 2005, 5:46 pm Post subject: Re: leaking head gasket

In order to retighten the bolts will the engine need removed?

grizld1 · Posted: June 24, 2005, 11:04 pm Post subject: Re: leaking head gasket

Nope. You'll need to take off the head stays at the top of the engine for the big head nuts. For the two near the spark plug holes, remove the chrome cam covers, grind down a 12mm 1/4" drive socket, bend a 90-degree angle in a piece of 1/4" square stock, score a groove 12" from the socket center in the square stock, and hook a good spring scale (I use a Rapalla fisherman's scale) in the groove. Pull at a right angle and read the scale. That way you don't have to tear down your ignition to get at those
critters with a torque wrench!

whynot2 · Posted: June 26, 2005, 9:13 am Post subject: Re: leaking head gasket

Harbor Freight used to sell a 1/4 inch drive torque wrench. It with the appropriate socket works fine. Also some of the later spec's call for less torque than earlier published numbers. Like the earlier post said, do them, do them again, and then do it again. WN2

whynot2 · Posted: June 28, 2005, 1:41 pm Post subject: Re: leaking head gasket

That torque wrench is still available from harborfreight.com for 28.99, online stock number #2696-3VGA. It is inch pounds so a little math is involved. It has worked very well for that hard to reach bolt under the spark plug with a small 1/4 inch drive socket, put the socket on the bolt then attach the torque wrench. WN2

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