Base Gasket

[motor mitch]

I mentioned in my first post that my base gasket leaked but until a recent 75 mile ride, I didn't think it leaked enough for me to wan to do anything about it. I was wrong. So now I'm coming to the experts. I imagine there is a thread somewhere with how to do this but I haven't found it. Is it worth me looking for a new engine or doing the work myself? Where do I need to get parts and what parts will I have to replace or want to replace? Any and all advice and help will be appreciated. I know this is a bigger task than I intended on when I bought the bike, but I'd still say for $900 is was a steal. Just so everyone knows, its a 1981 XS1100 Special, the SH model.

[crazy steve]

First, make sure it's really the base gasket that's leaking. Chances are good it's the cam chain adjuster and the oil is blowing through the cylinders and running along the cylinders' base. The adjuster is between the middle two cylinders in the front of the motor; if it's wet with oil, that's probably the problem...

[trbig]

These tend to leak oil from so many places that makes it LOOK like it's comong from the base gasket, that I'd sure rule everything else out before doing an engine teardown. The base gasket has no oil pressure going to it, so it would only be seeping. The cam chain adjuster is a notorious spot as well as the valve cover. Wind blows the oil through your head (On the bike ) and it drips down on the back side of the motor and fins that makes it look like the base gasket.. when it isn't. There's also crank seals and galley plug seals under the engine sidecovers that can leak oil back into the back side of the motor.

A teardown can be done by a first-timer, but I recommend having someone there that has done it before to assist. A good assistant can usually be bought with some adult beverage and charred animal flesh.



And Steve types faster than me.

[crazy steve]

Should point out that if it is the adjuster leaking, this would be a great time to upgrade with one of these... http://www.xs11.com/forum/showthread.php?t=35501

[natemoen]

Agreed that it likely is not the base gasket and more likely something else. Check everything else first, then check again, and then one more time before pulling the engine apart.

If you do pull it apart, no need for a gasket down there. Use anaerobic gasket maker as a gasket. Don't use regular gasket maker. The anaerobic gasket maker will not set up until it has been torqued down so then you can walk away from the project every time you get pissed at trying to get the cylinders back on and not have to scrape and replace the dried up gasket maker each time.

[GLoweVA]

Agreed that it likely is not the base gasket and more likely something else. Check everything else first, then check again, and then one more time before pulling the engine apart.

If you do pull it apart, no need for a gasket down there. Use anaerobic gasket maker as a gasket. Don't use regular gasket maker. The anaerobic gasket maker will not set up until it has been torqued down so then you can walk away from the project every time you get pissed at trying to get the cylinders back on and not have to scrape and replace the dried up gasket maker each time.

Yeah, what Nate said about the correct gasket maker stuff.
I used the wrong stuff on my G when I did my piston replacement last summer and my base 'gasket' leaks.
It doesn't leak bad, just a slight weeping, but it does make the engine dirty and drips a few drops on my carport. Sad part is, I had a complete gasket set when I did the tear down, but I forgot to put the new gasket on until after I had the jugs down around all 4 pistons. So, I just put my 'gasket sealer' stuff down around there.
It's now on my list of things to do during the planned overhaul of my G. (after I get my SG up so I'll have something to ride in the meantime)

[trbig]

If you know where the leak is, and since there's no pressure on that base, several people have had good luck with cleaning the spot and simply smearing some gasket material over the crack and fix the leak.

[clcorbin]

I just finished replacing my base gasket last weekend. I DID find a leak! Of course, it was only about 2% of the total volume... The rest was, you guested it, the bottom of the cam chain adjuster. Before I pulled the cylinder, I would have SWORN the oil was coming from the base and not the adjuster. I would have been wrong...

On the bright side, I did get the opportunity to visually inspect the piston, rings and cylinder walls before cleaning and putting everything back together. And I am happy to say that everything looks very good.

All in all, the process wasn't really that bad, especially if you have had the head off before. Be sure to soak the head studs with penetrating oil from top to bottom several times over the course of several hours before trying to remove the cylinder. Crap builds up in the cylinder around the bolts and packs in there over time like so much cement. It takes a while for the penetrating oil (I used Kroil) to soften up that gunk so the head can slide off the studs.

Oh, and you will have the WONDERFUL opportunity to clean all the crap off the case and cylinder gasket surfaces without damaging anything! Fun, fun, fun! That part took almost as much time as everything else together...

When you see how the cylinder fits to the case with the base gasket AND o-rings on each cylinder, you will see that the chance of non pressurized oil leaking through there is VERY slim, which is why everyone is saying look for the leak elsewhere. Cleaning the case just isn't worth it unless you KNOW you have a leak.

On other hint that may help: I just dropped the timing chain down into the case when I pulled the head and cylinder off. After getting the cylinder set, I used a 2 foot long piece of stiff wire (stainless steel safety wire in my case) with a short "J" hook on the end to reach down into the case and hook the chain. I then pulled it up and "flopped" it over the front of the cylinder while I set the head in place. Before dropping the head all the way down on the studs, I used the hook again to reach in from the top of the head and snag the chain and pull it back up through the head. I then tied off the wire to hold the chain in place while I got the head bolted down before I reinstalled the cams. Simple and easy.