Head Gasket Replacement

I'm looking to replace the cylinder head gasket and head cover gasket on my '81 XJ650 Midnight Maxim. Aside from the two gaskets themselves are there any other gaskets or parts that I would additionally need to replace?

Also, if there is a link to a video or anything like that with instructions that would be awesome. I have an understanding on how to do it, but some detail would be much appreciated.

Thanks!

 

There are two oil seals on the right hand side of the cylinder head which seal the oil feed to the camshafts. You should replace those and if it is a YICS motor the four O Rings between the head and cylinder block.



20.28 minutes into Mezzmo's assembly video the two large oil seals for the oil feed to the camshafts and one of the four O rings for the YICS are visible. The two copper crush washers below the right hand cylinder head nuts need replaced too to seal the oil feed.

 

Cylinder base gasket is almost guaranteed to be disturbed and leak later, along with o-rings at the bottom of the studs and cylinders.
Don't trust 40 year old soft bits that have become baked and hard to remain leak-free when worked on anywhere nearby.

 

Bingo. Valve cover gasket=no biggie, normal maintenance item. Head gasket=more of a project and as above could have knock-on consequences creating a potential need for an even bigger project.

So, my question would be: why do you want to replace the head gasket?

 

Exactly I should have told him to do a compression test first good point.

 

I haven't done a compression test just yet, but the head gasket does have a leak on the left hand side of the bike. The valve cover gasket on the other hand, has a more noticeable leak. I figured if I was going to take it apart to do the valve cover gasket, I might as well do the head too. Is it more common for a valve cover gasket to fail before a head gasket?

I read somewhere that you can always try to re-torque the cylinder head bolts before tearing it apart to see if that fixes the leak. Is there some truth to that?

 

This is one of the more detailed videos I've ever seen for these bikes. Thanks for sharing! If I end up going that route, it'll definitely come in handy.

 

Makes sense, thanks. I was actually wondering about the cylinder base gasket too.

 

Do a compression test first to make sure your head gasket has failed. Check the easy things first the 8 cam cover bolt seals and the cam cover to head gasket.

 

Valve cover leaks very often (as in almost always) make it look like the head gasket is leaking oil too. Change the valve cover gasket and doughnuts, clean the engine thoroughly, and see if both leaks aren't gone. Be sure to use a thin film of RTV on the half-moon portions of the valve cover gasket so that they seal well against the head.

 

Awesome, thanks. I'll do a test this weekend and see what it reads.

 

Makes sense, thanks for the advice. It sounds like the valve cover gasket will have to definitely be changed. Hopefully there aren't more issues, but I'll see what the test reads.

 

As I said, valve cover gasket is a common maintenance item, whereas head and base gaskets involve a lot more than just the gaskets.

Another thing to keep in mind: oil seepage, especially on a motorcycle, can be very "sneaky" in that things will appear to be leaking that are not, the leak is elsewhere and "migrating." Valve cover gaskets often leak into the inner spark plug galleries (#2 and #3) and then the oil runs down between the fins onto the front of the motor and makes you think you have a head gasket leak. I was just sure my '81 had a base gasket leak when in fact the cam chain tensioner gasket was the culprit, with the oil migrating all around the base of the cylinder block. Another potential source of sneaky leakage is the tach drive housing; because of its location, when the bike is in motion the oil can and will end up about anywhere.

 

I don't think the head gaskets fail very often on the XJ's. I had to change one on my 1974 Honda CB 750 years ago.

 

They don't. But they sure do have a propensity for "sneaky" leaks, oil migrating quite a ways from the source. Fooled me more than once. Not like my Norton, when it drips oil at least you know where it's coming from.

 

Off subject but it is just like flat roofs they are the same.

 

750 years ago?????

 

he also installed a flux capacitor

 

My CB 750 did more than 88mph.

 

Well, I did a compression test this morning and am not having great results... I had a reading of only 65-70 on each cylinder. I read that if you drop a teaspoon of oil in where the spark plug goes that that will give you an indication of whether it's the valves or the piston rings that could be causing the issue. I did it, and it bumped the compression up to about 90. Any ideas or recommendations on what a good next step would be? I'm wondering now if I'll have to tear the entire engine apart to replace the rings.

The bike ran great all summer, but just started giving me issues these past couple of weeks. I brought it home after putting a few hundred miles on it and it's been riding terribly ever since. The only thing that changed was that I had the headlight off at one point and didn't know if I had messed up any of the electronics that go through the headlight housing, but now it's looking like it's something unrelated.