Topic: Bottom end gasket product?? CB750

[andy750]

Hi all,
According to the CB750 factory manual you use liquid sealant for sealing the lower crankcase to the upper crankcase  -just went to the auto store and bought permatex "Ultra-Black" OEM Hi-temp RTV silcone gasket maker. Is this OK to use?? And if not what have other people used SUCCESSFULLY???
Thanks for any input (sooner would be better as we`re in the garage now :-))
Cheers
Andy

[El Taco]

I used Yamabond successfully. Bike didn't last long, but I won't attribute it to that. A buddy of mine used silicone on his Z1 and it clogged his oil pick up screen.

[kghost]

I used RTV silicone gasket maker on mine with no issues.

Just remember to run a Small bead. Don't overdo it.

[Quail "Owner of the comfortable k8"]

the reason liquid sealer is used, is when a 0 thickness is desired.  Liquid sealer is nothing more than an oil proof polymer that seals and never hardens so that it will expand and contract and still not leak.  That will be 2 cents please. please use pay-pal 

[bwaller]

Andy,

I've always used the Three Bond material but I know most shops now use a silicone. The trick is to remove all old material, make sure both surfaces are clean and oil free then apply sparingly to both cases

Brent

[CHUNG]

All the silicon based stufff is really too thick to apply a thin enough coat and you will squeeze goobers into the engine. A gasket shelack is a much better choice (sorry for the spelling) INDIAN HEAD is the only one that I have ever used, it mfg by PERMETEX and at all auto parts stores.
 You can apply a very thin coat to both pieces, allow it to gel for maybe 15-30 min and then assemble the parts. Let it take a full set for maybe a day before putting it into service. I have even used it on sidecovers with no paper gaskets at all and NEVER had a leak. Great stuff.
FYI.. A little trick I recently learned, store your containers upsidedown and the VOCs can't get out and cause it to take a set in the container.

[MRieck]

3 Bond 1104, Hondabond, Yamabond...all the same and that is what I use 99% of the time. The new ultra silicones are excellent too and are used by the factories. A friend of mine uses a flexible sealer made by Mercedes- it works well too.

[Warlock]

Greets,
Add one more option to the list. I have used Hylomar in the past without any problems...

[Dennis]

Chung,
I remember my father using Indian Head gasket shellac way back when I was a little kid. As I recall it seems that the product they were selling back then made disassembly a little difficult.
Have you ever taken one of those engines apart after sealing it with Indian Head?
How difficult was it?
Or have things changed for the better?

[kghost]

I occasionally use the Indian Head. Good stuff. Little hard to get off once set, and you won't get to re-use the gasket.

[Terry in Australia]

I lost a perfectly good 750 top end to silicone splashed on by an ignorant PO, and won't use it, Period. Make sure you apply enough sealant around your ignition side crank seal though, I must have applied the stuff "too" sparingly, and now I get an oil drip either side of the seal. Ah well, I had to strip the engine down again anyway, boo hoo! Cheers, Terry.

[andy750]

Thanks to all those that responded, and feedback very much appreciated. In the end went with Hylomar from Permatex- after doing a search and finding BMW mechanics use this stuff with success -and there was an old post of Terrys in the archive that had recommended it....so time will tell. We almost bought Indian Head so thanks for the tip Chung, perhaps nect time if this fails.
Thanks,
Andy in Boston

[cben750f0]

yeah use the permatex aviation goo, never goes hard, but is resistant to EVERYTHING.. was recommended by a mechanic that is in the know with cb's... so who am i to argue...peace

[frostypuck]

Don't worry Andy, it won't leak. If it does, then you can try an experiment of all the different suggestions, like maybe a 6 inch bit of each and then test the outcome. If the engine grenades, we'll assume it was the silicone.
Chris

[bhkrause]

Ok, need to bump this back up to the top..      Seems to be the only thread I could find on the topic.

Anyone ever use Loctite 518?  Ex-mechanic and current mechanical engineer bro-in-law recommended it, and I do trust his advice, but any experience here?

Also - when you're putting the stuff on - all the way around all the bolt holes, or just one side of them?  Doing a practice run for the 750 by putting my 400T back together.  Finally..

Tanx!

[Terry in Australia]

Ok, need to bump this back up to the top..      Seems to be the only thread I could find on the topic.

Anyone ever use Loctite 518?  Ex-mechanic and current mechanical engineer bro-in-law recommended it, and I do trust his advice, but any experience here?

Also - when you're putting the stuff on - all the way around all the bolt holes, or just one side of them?  Doing a practice run for the 750 by putting my 400T back together.  Finally..

Tanx!

G'Day Bernie, it was a Loctite sealant that I used on my F2 that now drips out the ignition points cover. I can't remember which, but I'll check and get back to you, I wouldn't wish a strip and rebuild on anyone! Out to the garage I go! Cheers, Terry.

[jacquesleclochard]

Terry? Still in there?

[martin99]

I've always used Hylomar, even on vertically split Brit twins and had no issues.

[martin99]

Errr, just realised how old this thread is. I would imagine those cases are back together by now. Doh!

[jacquesleclochard]

[Terry in Australia]

Terry? Still in there?

Yeah mate, I'm still here, but I had to split the cases and re-seal them with Threebond 1104. Cheers, Terry.