engine rebuild: gaskets, sealants, silicone/rtv, loctite

[GregTheKeg197]

Doing a top end rebuild on my 72 xs motor.
I bought the mikes xs Athena gasket kit and all the goods, blah blah but..

I would like some of your guys wise opinions on where you should use (or to not use at all) on an xs rebuild:

blue Loctite
silver anti-seize
permatex gasket sealer
permatex rtv silicone
permatex gasket spray adhesive (red tacky sh!t)
(basically that's the stuff I currently have on me above)


let me know what you guys think...

 

[abyssmaltailgate]

I see this post is a couple years old, but I too have asked myself the same question. Unfortunately there's not a a master thread or place on this site where this has been concisely stated that I've found; however, there are a lot of nuts, bolts, and gaskets on these bikes so attempting to cover this topic seems like quite the chore.

I'm no professional (so it'd be nice if the pros chimed in here), but I and those I know tend to use either red or blue Loctite on all the critical engine fasteners such as the crank case nuts and bolts; however I see Hugh uses a dab of blue and a dab of anti-seize.

Would like to know more on all these topics...

 

[retiredgentleman]

I'm no pro, but I can suggest a few things.
Anywhere that you use a gasket, there is no need to use any sealant at all. The rocker cover does not use a gasket, so I used
Three bond 1104 ( Yamabond/Hondabond is similar I believe). With the head gasket it's become standard to use some Three bond 1104 around the 4 outer studs and around the camchain opening; also at the front edge. 5twins has a good picture showing this.
Even though no sealant is normally used with gaskets, I will use a small amount of sealant if I find a gasket that wants to leak. My starter motor gear cover, on the left side, always leaked a little, so I used some sealant and that stopped the leakage.

Some lads like to put some grease or motor oil on a new gasket. Grease one side only so it sticks to the part that come off.

For most steel bolts going into steel or aluminum, I use an anti-seize product, and no lock-tite. I find no need to use lock-tite, except for some small bolts/screws, such as butterfly screws on the carbs, headlight bucket bolts, gear shift lever bolt, and a few other small bolts. I use some blue lock-tite on those just mentioned. I never use red lock-tite.

The most important thing is to always use a torque wrench and the correct amount of torque. When I have a steel bolt going into an aluminum part, I tend to only use the minimum amount of torque that will be secure and not leak. I may be below the recommended torque, but it lessens the chance of stripping the thread.

One place is an exception, the spark plugs. I keep those threads dry, and always fully thread the plug in using my fingers.That allows you to feel if its threading in correctly, and not cross threading. There is a danger if you start adding anti-size, the threads become gummy and you may cross thread it.

 

[grizld1]

There's always more than one way to skin a cat. Never a need for sealant on gasketed surfaces? With all due respect, RG, that depends on the surfaces! If you're installing the cylinders on the case and notice a few more scratches or dings than you really like to see but not enough to set you to pulling studs or running to the machine shop, you can get good results (and peace of mind) with a tough sealant like Permatex Ultra Black. Need to install a petcock adapter plate? Cut a gasket and install it with Gasgacinch for a fuelproof seal. Installing the head? For a seal at the cam chain tunnel and oil bearing stud holes, I don't use Yamabond, etc.; it sets up too fast for my taste, and I don't like to be rushed. I spray the head gasket on both sides with Permatex copper gasket spray; just hang the gasket up, shoot it, and let the compound cure for as long as you like. I haven't had a seep yet in a lot of years and a lot of assembly jobs. The best thing about the stuff is that it releases when it's time to take things apart again, so unless more aggressive measures seem to be called for, I use it on the base gasket too.

Athena gaskets, eh? Greg, I've posted this before, but you're getting a set with a head gasket that's around .016" thicker than OE and a bunch of other gaskets made of slippery green stuff. Think about using Vesrah gaskets in the future: they're the real thing, made in Japan to OE quality and specs.

 

[YamadudeXS650C]

Like RT and Grizld1, generally I successfully use a greased gasket (only) on most applications in which a gasket is called form , yet I also come upon the occasional situation with these old bikes where the mating surfaces are abnormal in some way. Additionally, this year I picked up a 1980 XS650 which had 2 valve cover studs which were mostly stripped out, and I was able to get them pretty well solidified into the head using JB Weld in one case (intake), and Permatex red for the other (exhaust).

However, I wanted to minimize the torque value in order to not break up the limited "hold" I had made on these studs, so I used a sealant, first with an Athena gasket (unsuccessful), and then with just a sealant.

I generally use Permatex sealants and gasket makers, as they do ongoing research, and they have techs we can easily access on the phone, and they usually will talk to you at length. For this application, I shared with the tech that I was thinking of using Ultra Copper. He said no, and that there was only one appropriate Permatex sealant, which is "Motoseal 1" for 2 and 4 cycle engines.

Curiously, The Permatex tech advised me to ignore the package and online instructions for all of the Permatex sealants and gasket makers! Rather than to "apply, then wait a minute, then assemble and torque to specs", he said that the proper instruction is to apply, then assemble, then torque only finger tight ("dont squish out the sealant), then wait an hour, then torque to spec. This worked (100 miles test) for my valve covers, and I even used a smaller torque figure.

 

[XSLeo]

RTV/silicone is not recommended by myself or others. This type of sealer tend to squish out and form beads of sealant. On the inside of an engine these beads can come loose and possibly plug oil passages.
I don't know about others, but I don't think the risk is worth it. I use Yamabond or the Three Bond equivalent.
It's a lot less expensive than a rebuild.
Leo

 

[YamadudeXS650C]

Leo,

Knee-jerk responses are rarely helpful.

Motoseal is not an RTV sealant, the latter which are silicone-based. Motoseal is a solvent-based, liquid polyethylene rubber product, which is quite different.

Additionally, the main point of my post was to point out that the Permatex tech advised against the torque-squishing procedure. This might minimize the possibility of particles in the oil, but of course it would not for sure guard against that possibility. I suggested the product for very unusual circumstances such as my valve cover situation. The alternative would be to tap the threads, which I was prepared to do, but tapping brings with it a small possibility of things going awry, and the head being damaged. I prefer to avoid surgery, if possible.

 

[5twins]

I've heard good things about the Motoseal. I will probably try it when my stash of original formula Yamabond/Hondabond runs out. That copper gasket spray sounds interesting for the head and base gaskets too. Much easier to work with, it seems, than the Yamabond.

That Motoseal appears to be a copy of the original Yamabond/Hondabond, which would be a good thing seeing that their formulation has changed.

 

[XSLeo]

Yamadude, I wasn't speaking in reference to Motoseal. In the OP's opening post he listed RTV/silicone, I was speaking to that.
Leo