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4.125" bore...retain o-ring?

Started by scoopfraser, May 16, 2020, 07:52:02 AM

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scoopfraser

I did some searching, but couldn't find a clear answer.  I've got a 2000 FXD and I'm considering my options.  I'm thinking either a 111" (4.125 squared) or a 117" (4.125" bore/4.375" stroke).  My question is when boring the stock cases for the 4.125" cylinders is the cylinder base o-ring able to be retained or does one need to go to a gasket?

Thanks!
2000 FXD
Edmonton, Alberta

Deye76

Think 4" bore is largest to retain o-ring. My 4.060" lost it.
East Tenn.<br /> 2020 Lowrider S Touring, 2014 CVO RK,  1992 FXRP

Don D

Your bore will eliminate the oring counterbore. Bore the cases per the S&S 124 instructions and be done with it.

Ohio HD

Quote from: scoopfraser on May 16, 2020, 07:52:02 AM
I did some searching, but couldn't find a clear answer.  I've got a 2000 FXD and I'm considering my options.  I'm thinking either a 111" (4.125 squared) or a 117" (4.125" bore/4.375" stroke).  My question is when boring the stock cases for the 4.125" cylinders is the cylinder base o-ring able to be retained or does one need to go to a gasket?

Thanks!

You can see how close the new case bore for 4-1/8" cylinders is to the studs. No room for an o-ring relief cut.


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Ohio HD

A zoomed image shows the case bore in relation to the witness marks the cylinder bore for where the studs sit on the case. The new o-ring if made that large would push up into the bore on the cylinder holes for the studs to pass through.



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turboprop

Quote from: scoopfraser on May 16, 2020, 07:52:02 AM
I did some searching, but couldn't find a clear answer.  I've got a 2000 FXD and I'm considering my options.  I'm thinking either a 111" (4.125 squared) or a 117" (4.125" bore/4.375" stroke).  My question is when boring the stock cases for the 4.125" cylinders is the cylinder base o-ring able to be retained or does one need to go to a gasket?

Thanks!

Did your online search include looking at the contents of gasket sets for 4.125" TC cylinders?
'We' like this' - Said by the one man operation.

prodrag1320

you`ll have to run a base gasket,no large O ring,on 4.125 builds here,i still use the small dowel O ring under the gasket though

scoopfraser

2000 FXD
Edmonton, Alberta