Topic: Gasket Replacement Dressing?

[jwalters]

Hello, I am replacing my alternator cover gasket and the clutch/transmission cover gasket on the left side of my CB750K2.  I have cleaned off the old gasket, and ready to install the new ones.  My question is, should I add a dressing to either side of the new gasket before I install them?  Or can I install the "dry" gasket as is, replace the cover and bolt together?
Thanks
jesse

[Terry in Australia]

G'Day Jesse, well I installed mine dry after an engine rebuild, and it leaked like a seive! All the old gasket material was meticulously removed as both engine crankcases were chemically cleaned, so nothing but bare alloy contact. Use some "Three Bond", YamaBond", "SuzyBond" etc, but nothing that contains silicone, or you'll be so sorry you'll cry like a little girl! Cheers, Terry.

[JakeLee]

Funny...I actually thought ahead last year before I bought mine and asked the Honda parts guy with 10 plus years experience about that.  He said no sealing was needed since the new gasket would swell with the hot oil and seal due to the type of coating.  Sure enough, I tightened everything to spec and got a couple drips in the first few running minutes from under the alternator cover, but after a half an hour of putzing around, it was dry as it was when I wiped off the first drips.  300 miles later and still no issues.  (No blue finger tips either, blue RTV is usually my best friend)

My surface was not immaculate either with a few scraps into the aluminum with a utility blade to blame for that.  Just my experience!

[jwalters]

Thanks a bunch for the reply!
jesse

[mick750F]

   I replaced the same gaskets a couple of tears ago and just moistened them with oil before assembly...no leaks yet. Of course now that I've posted this I'll probably have some tomorrow.

Mike

[dpen]

Gotcha Terry-there is one silastic sealant you can use. It's called "ultra blue" and is impervious to all oils (including auto trans) and petrol. It even seals exhausts. My wifes' car is held together with it and you don't want to know about the bike.

[Terry in Australia]

If you're not as lucky as some of the previous posters and do need to use a sealant of some type, don't use silicone as any excess will travel through your oilways and block them. The most common cause of premature catastrophic top end failure in 750/4's is silicone sealant blocking the oilways in the cylinder head.

It only happened to me once (killed my K1 when a Triumph mechanic rebuilt my top end and slapped silicone in every mating surface, as he was used to when repairing those old limey rattlers) but I ended up having to pay for new pistons, rings, rebore, cam, cam towers, rockers, etc etc. Very painful indeed. Cheers, Terry.

[dpen]

All depends on how ya use it. Put it on with a trowel & you're rat sh*t, dab it on very sparingly & it's magic

[Jonesy]

I've always used Permatex Form-a-Gasket sealer. I just put a light film on both sides of the gasket and it works just fine. It's meant for use with both new and used gaskets. It looks like baby sh*t, but it does the trick!

[jwalters]

Note to self, "Use baby poop on gasket... got it!"   

But seriously, thanks!
jesse

[barber1303]

Might as well throw my 0.02 in here...

I use Permatex gasket dressing and flange sealant on everything but the high temp gaskets.  It never dries and prevents the gasket from sticking tight to the metal, which allows you to remove and reuse the gaskets.  If you use it sparingly (appropriately) it helps seal and won't toss chunks of hardened material into your crankcase or intakes.

Chris

[Terry in Australia]

The oilways in a CB750 head are about the same size as the main jet in your carbs, so a piece of silicone the size of a match head will block them, and your whole top end is toast. Honda make their own sealant, as does all the other Japanese bike manufacturers, so why risk using anything else?

Permatex is fine, as is Hylomar blue and ThreeBond (which looks and smells just like the Honda product) and I've never heard of a failure caused by this stuff. I'm sure there are plenty of other sealants that are safe to use with our bikes, so can't see any need to go the silicone route. I say leave it where it does the best good, in porn stars boobs! Cheers, Terry.

[dpen]

OK Terry, I give up. I can't compete with porn stars boobs

[smithrelo]

Yo! Guys!  Keep it clean, or ...

I'll have to start my own thread:  "Man-bits" and the ladies will discuss the different parts of a bike that remind us of "man-bits".  (LOL)

Linda

[Terry in Australia]

OOPS! Sorry Linda! Cheers, Terry.

[cb750_chris]

Is a light smeer of gen purpose grease good to use when puting head gaskets back on?  This has been recomened to me for when I tear into the top end.  I don't want to put anything on the gaskets that will permanently fix the top end to the case!!!

From looking at the top end it may already be sealed down by the previous shade tree.  I'm sure I'll have fun with that one.   

[Ibsen]

If you smear a thin layer with oil or grease on the mating surfaces before you put on the gasket, it will seal. And by doing that, it is very easy to remove the gasket the next time you have to take the cover off. I had an incident a few years back with an oilway that was clogged by silicone, so I'm very careful with the stuff.

[jwalters]

Interesting, I ordered some "Honda Bond" from our local dealership in town (recommended by the mechanic).  After reading the back of the package,  I noticed it is silicone based!  Well, I think I am going to take it back, and go with one of the above mentioned non-silicone based products.
The mechanic did say the only place I needed the "Honda Bond" was around the little rubber grommet that had wires running through it.  The rest, he said, could be left uncoated.

thanks
jesse