Base gaskets of varying guages?

[Rudemouthsky]

When installing high comp pistons, I have heard of people setting squish by using base gaskets of assorted thickness. Looking at the parts catalogue for my 900SS motor I see 3 different gaskets here, the vertical only has one part # listed, and the horizontal shows 2, a 0.3 and a 0.4. Called Ducati Seattle and they only know of one kind of base gasket. A Google and forum search turned up nothing. I understand many people don't even use base gaskets, so I'm a bit confused. I also see I can buy a top end kit for $34 but I already have nice new metal valve cover gaskets, and a very comprehensive metric O-ring kit. I don't want to go into this without the parts I need but I don't want to waste $$ either...

Those of you who have installed JE pistons, what gaskets did you wind up needing, and where did you get them?

Thanks...

[Ddan]

I wound up using no base gaskets to get good squish numbers.

[Rudemouthsky]

Hey Dan;

On your SS or ie?

[Ddan]

The SS, same motor as in the Cylinder Scuffing thread, so take anything I say with a little skepticism   

[Speeddog]

Cometic has base gaskets, and routinely makes custom ones.

[Rudemouthsky]

The SS, same motor as in the Cylinder Scuffing thread, so take anything I say with a little skepticism  

So did they literally end up "dropping in" for you Dan? your tolerances were ok without any modification?

where's this scuffing thread, haha...

edit: found it. A, B, and C cylinders...wow that's weird. So I wonder which letter JE used to size their pistons?  

Dan I have 96' SS jugs for sale BTW...I can snap pics and find out if they are "A,B, or C" for you. I'd sell em cheap and you can return em if they don't work for you.

[Ddan]

Mine are already sent out for plating and matching to my pistons.  I don't know how much variation there is in the pistons as delivered from JE but mine would have been an acceptable fit in an A cylinder

[Düb Lüv]

Fastfrankracing.com sells thinner base gaskets.

[Rudemouthsky]

Fastfrankracing.com sells thinner base gaskets.

Thanks for the tip DL

[hooligan machinist]

 I made my own.
All it took was some steel shim stock of the proper thickness, tin snips, and a steady hand.
They were not very pretty, but once in place, not noticable and didn't leak.

[brad black]

I've checked with je fitted and they're about right as is.  you can leave the base out with std pistons, and the issue is only right at the outer edge due to the different angle of head versus piston crown

[Rudemouthsky]

I've checked with je fitted and they're about right as is.  you can leave the base out with std pistons, and the issue is only right at the outer edge due to the different angle of head versus piston crown

Brad:

"As is" as in *with* the base gaskets supplied in a Ducati OEM top end kit?

thanks

[brad black]

yes

78610391a is 0.30mm, 78610471a is 0.4mm.

391a has a smaller id, and while they work on both one of them needs an extra cut out for the oil return.  I think 391a is nominally horiz, and 471a vertical.  I forget now.

[koko64]

Good to know.
Thanks guys.

[Rudemouthsky]

 thanks Brad