putting cases back together, silicon OK?

I know that hondabond or similar products are made for sealing the upper and lower engine cases, but if I cant find any, would the proper type of silicon work just as well? My uncle (with the 548ci drag corvette) said it would be fine, what does everyone else think? thx
Scott

Silicone might work, but I woudn't use it.
The upper and lower main bearing shells ride directly on the upper and lower case halfs. The main bearing clearance is determined by how close the cases bolt together, if the sealer is to thick then the main bearing clearance will be excessive, if it's to thin then there may not be enough main bearing clearance.

I don't know the specs for the silicone or the Yamabond/Hondabond/etc (made by ThreeBond I think), so I use what the manual specifies.

Better safe than sorry IMHO

Post edited by: steell, at: 2006/05/01 19:22

steell wrote:

if the sealer is to thick then the main bearing clearance will be excessive, if it's to thin then there may not be enough main bearing clearance.
I use what the manual specifies.

if the sealer is a liquid, and if the cases are torqued to spec before it dries, wouldnt all types of sealer "flatten out" to the same thickness?
what does the manual specify? (dont have one yet)

Each type of sealer will flatten out a different amount at a standard load, there is a spec for this but I forget what it's called.

I just checked the KZ650 manual and it specifies "Liquid Gasket"

But I still would not use silicone.

You are perfectly welcome to do so though, just let us know if it causes any problems, or if it works fine.
I'm just chicken

Post edited by: steell, at: 2006/05/01 20:09

use a thin bead of silicone,let it set up a little before bolting cases together.you want just enough silicone to seal cases do not glob a whole tube on there! goodluck,happy wrenching!

steell wrote:

Each type of sealer will flatten out a different amount at a standard load, there is a spec for this but I forget what it's called.
ah, I didnt know that, but since these liquids are very similar, they should have very similar "flattening out" properties?
I just checked the KZ650 manual and it specifies "Liquid Gasket"
Ill have to look around for this stuff too
But I still would not use silicone.

You are perfectly welcome to do so though, just let us know if it causes any problems, or if it works fine.
I'm just chicken
Ill give everyone an update of how it works if I go with silicon

wireman wrote:

use a thin bead of silicone,let it set up a little before bolting cases together.you want just enough silicone to seal cases do not glob a whole tube on there! goodluck,happy wrenching!

ah first hand expirience, just what I wanted:)
yeah, big globs of silicon dont belong on/in a bike
how long is "a little" for letting it set? 5 min?

give it a few minutes to skin over.we had a wonderfull discusion the other day about using silicone for dyno cover gasket.:whistle: :woohoo:

i have heard several people using 3 bond ( same as honda bond and many other names , they are mostly the same though just under another name)

but, by using this this will bring the head and cylinders ever so slightly closer to the case. this will bring the compression ratio up slightly. this could be a plus or a negative. which ever you choose.

many drag mike guys that i know do this to bring up the comp. i do not recomend straight silicone though. the 3 bond will work.

good luck withe the project, mine isstarting to look like a bike again!!!!!!! i am getting the itch!!!!

sbjones wrote:

i have heard several people using 3 bond ( same as honda bond and many other names , they are mostly the same though just under another name)

but, by using this this will bring the head and cylinders ever so slightly closer to the case. this will bring the compression ratio up slightly. this could be a plus or a negative. which ever you choose.

many drag mike guys that i know do this to bring up the comp. i do not recomend straight silicone though. the 3 bond will work.

good luck withe the project, mine isstarting to look like a bike again!!!!!!! i am getting the itch!!!!

im referring to the case halves,not the base gasket on the cylinder.always use a gasket for cylinder base.

Silicon tends to break up and will get into your oil supply. Once in the oil, it has the chance of getting into your oil journals and plug them. I have seen silicon floating in oil and cam shafts with bits sticking to them. www.z1enterprises.com sells Threebond case sealer. Buy some from them and do the job right.

On another note, if you ask a question, you are likely to get at least one person giving you the answer you want to hear. If in doubt, call a local auto engine rebuilder in your area and ask them about silicon for sealing engine parts or any professional bike mechanic. FWIW: I have rebuilt about a dozen KZ engines so far this year. I don't advertise repairs or engine building but folks seek these services out as most repair shops won't touch older bikes so I do this but do it more as a service than something I want to do on a continuing basis.

Use Yamabond #4 or the Honda or Kawasaki product which are all basically the same. This is the semi-drying gasket sealer. At the best silicon makes a huge mess even if you're careful. I'm sure it would work if you do a very careful job as wireman pointed out, but to me, silicon is no good as a sealer as it takes a 100% dry oil free surface to bond too. Try to get those cases 100% oil free on both halves, good luck on accomplishing that task. Better off never using it for the most part.