Copper head and base gasket???

Posted: Sat Feb 07, 2015 6:55 pm

I know rookie? But isn't one of the main reasons for copper gaskets is that they don't squish and stay at the desired thickness? Or do the squish and if so? How much is average?

Thanks guys. Jim

Posted: Sat Feb 07, 2015 6:58 pm

Cometic will tell you how much they squish for a given torque value.

Posted: Sat Feb 07, 2015 7:43 pm

Copper gaskets don't compress. If it's a .041" thick gasket use that for your number when you're figuring compression and piston clearances. MLS and "organic/paper" gaskets compress so if you use those be sure to know the compressed thickness in order to get the correct math.

Posted: Sat Feb 07, 2015 7:44 pm

Bummer their closed on weekends. I'll look on their web site. Maybe it will show?

Just hoping someone knew the answer off the top of the head.

Peace, Jim

Posted: Sat Feb 07, 2015 7:45 pm

Oops. Sorry Jim. Coulda swore I got a squish value for my 428........But that was a long time ago.

Posted: Sat Feb 07, 2015 7:49 pm

Sweet, Nathan!!

I thought this was one of their purposes but I can't mess up on this measurement.

Peace, Jim

Posted: Sun Feb 08, 2015 12:25 pm

I thought this was discussed before and that there was some compression but like a thou or two ???

searching now

Posted: Sun Feb 08, 2015 2:07 pm

Found this
http://www.cb1100f.net/modules.php?name=Forums&file=viewtopic&t=70330&postdays=0&postorder=asc&highlight=copper+gasket+thickness&start=30

Shawn's post Mar 24, 2013 @ 5:58

That is not the post I was thinking about but it does talk about .002 compression

CB1100F Joined: Jun 18, 2006 Posts: 2523 Location: UK

JJam wrote:

Sweet, Nathan!!

I thought this was one of their purposes but I can't mess up on this measurement.

Peace, Jim

Jim as you are having new pistons made i would be tempted to leave the cylinder in the position so you can skim a bit off it when you have everything back and do a dry assembley run

Maybe aim to have the new pistons .010'' or so down the bore, i know the ideal is to have the pistons flush with the top of the block and just use the head gasket for your squish

Keith

Posted: Sun Feb 08, 2015 4:07 pm

Have you reduced the pin to crown distance in the new piston design?

Jim

Posted: Sun Feb 08, 2015 7:38 pm

Form my two cents Jim I always used copper head gaskets in applications where I would be re-using them over and over, like on my 2 stroke motocross bikes where we (occasionally) had to teardown the top end between moto's. They only required re-annealing every once in a while. I have used thin copper base gaskets with Weisco 1123 kits but they still use composition head gaskets.

Posted: Sun Feb 08, 2015 9:32 pm

jkotsi wrote:

Have you reduced the pin to crown distance in the new piston design?

Jim

Yes by .063" lets me use a longer rod and with the 60mm stroke that I now have and the 750 length barrels, I could get away with 1100 length rods but I'm still measuring so don't quote me.

I want to use .038" copper head gasket for the squish and a .010" base gasket with the head skimmed to the limit of the valve seat edge. If I run anything thicker then the cam chain gets tight to install with Brents parts.
I have to figure all of this in and its making my brain smoke as I suck at math.

Thank You guys for all the input. I believe I got it all sorted out now.

Peace, Jim