Hello fellow Americans!

I've picked up a chrome fox 25RC off ebay, believing it to have a 0.738" bore (aka early models).

To cut a long story short, the piston in my 29X is cooked. Maybe the piston on this ebay puchase would be suitable; (however on closer inspection I discovered these later engines to be 0.680" * 0.680".

So as I've completely stripped this beauty, I would be grateful if anyone could tell me the correct threads Fox used for these later units.


..........it ain't UNC is it?


Tim

Fox engines use standard hardware.  Try 4-40, if they're too big try 3-48.

   Almost certainly 4-40, in fact. Just to be absolutely safe, however, at least try to thread a 5-40 in there. It wasn't that way from the factory, but it is possible that someone had previously stripped it and replaced it.

     Brett

I vaguely remembered having trouble finding screws for a 25, (4-40s didn't fit), so I dug one out of the stash.  If it's the shiny case, 4-bolt backplate 25 like the one in the pic, they should be 3-48s.  The earlier 3-bolt back plate 25 used 4-40s, as did the BB IIRC. 

Thanks Dennis, that's saved me alot of hassle.