Liquid Gasket Sealants

[DJRacing]

Yamaha YZ's dont use a centre gasket for the cases, they just need sealant (yamabond).

[PEZBerq]

Help!!! Just pulled my cases apart for the third time...... Failed a 3 psi pressure test using the grey Threebond and the paper gasket the first time.  Leaking out the casing main half joint. 

How long should you wait until doing the air test?  I put about 20kPA in - 3psi after buttoning up the cases with the Threebond and it pissed out.  Should I have waited for 24hrs or so for the Threebond to cure properly?

I used a really thin smear of Threebond on the casing halves.  It seemed to have gone dry before I finished and stuck the halves together.  Is this OK or should I have used a thicker smear that takes longer to dry? 
Anyway then decided to try paper and smear of grease for the second attempt (seemd a good idea at the time).  Still no good - leaking air same as before.

Pulled apart for the third time and now wondering what to try next.  Half joint surfaces appear reasonable - not perfect but were sealing Ok before the tear down to fix sticking gearbox.  Torqued up screws to factory 6 ftlbs and checked them so half joint should have correct clamping force on it.

Any suggestions?  Pokey mentioned Hylomar..is that a sealant of last resort? 

[oldfart]

Try a straight edge( steel ruler ) on your case surfaces and check for warping ......then use loctite 515

[pokey]

Hylomar is what rolls royce use to build thier engines if ya can believe the can.
 I like it as its not messy and works well and is easy clean up when doing repairs

[Colin Jay]

This might sound pretty rough, but back in the early 80's while working at a Yamaha dealership, the mechanic would use contact cement (the yellow glue that you allow too dry on both items before putting them together) to seal up any centre case joint that leaked when 3-bond wouldn't seal the joint. It worked every time, and I will admit that I have used this method on some of my older engine, i.e. my 1949 Matchless G80, and it doesn't leak from the centre case joint. It leaks from most of the other though!

I use Loctite 515 on all of my 500 Yamaha engine and have not had any problems with leaks.

CJ

[Rossvickicampbell]

and to answer the question I normally leave my gasket/goo setup for 24 hours before filling with oil etc - learnt it the hard way - it appears most of the new goos require the setting time.

cheers

Rossco

[maicomc490t]

Loctite 515

I've rebuilt shitloads of Ducati's among other things in the past using the stuff and I can't fault it

[PEZBerq]

Left the sealant to cure for 24 hours and the air test was successful finally.  What a goose......expecting liquid sealant to seal while it was still liquid Now to see if the jetting problem has been fixed......... Thanks for the help.