is there a right and wrong piston order?

[Jscobey]

im referring to the JE high compression pistons. ive seen the stock pistons which say F and R on them, but the JE's i have arnt marked at all. ive read that someone had major problems after installing the pistons in reverse.... is there a way to tell which is which?

[lloydie]

I hope so !!!

[sirch345]

I think the cut-outs in the piston crowns are different for the exhaust and inlet valves. I'm not sure if this is both width and depth. Have a word with Tonymon,

Chris.

[darkember]

I think the cut-outs in the piston crowns are different for the exhaust and inlet valves. I'm not sure if this is both width and depth. Have a word with Tonymon,

Chris.

I believe Tonymon got it wrong so before fitting them have a word with him he should be able to set you on the right path

[tony.mon]

I certainly did! Mind you they ran fine for two and a half years....

You can tell by the size of the valve cutouts, big cutouts are for inlets.
Don't go by the size of the lands, which is what I did- that's the opposite way round to standard, as I now know.

[VTRDark]

There's a snippet of info in the following referring to Gudgeon pin offset. Not sure if it the same with the JE's



(:-})

[Jscobey]

okay so i got which direction the pistons go, but what about front and rear cylinders? and order there?

also does anyone know why the inside of the JE piston is stamped 97mm? checked the engraved part number against JE's website and they are the right pistons.

[lloydie]

They might be for the 995 engine not the 996 !!!!

[tony.mon]

okay so i got which direction the pistons go, but what about front and rear cylinders? and order there?

also does anyone know why the inside of the JE piston is stamped 97mm? checked the engraved part number against JE's website and they are the right pistons.

No, they're the same front and rear; so are the heads, and as far as I'm aware, so are the std cams, although the cams are marked front and rear as well as in and ex.

As regards the size; they are actually slightly smaller than 98mm, to allow for expansion and clearance, so are technically less than 98mm, even though the bore is 98mm.
It will give the machined diameter on the paperwork and cad/cam machining info that came with the pistons, have a look and see what I mean.