Forum

[Dennis C]

Pete I just fitted a pair to my Triumph Tiger 110 with no direction marking, some pistons are split skirt and some have a bigger cut away for inlet valve clearance, as for as I am aware these are the only thing which makes them directional.

[Bullet Whisperer]

Time to get pedantic here - there are some pistons whose gudgeon pin bosses are offset from the centre line of the piston, desaxe engines, like the AJS / Matchless 'unit' singles, for example, where the entire cylinder barrel is offset forwards very slightly. Also, closer to home [and I may be wrong here], I am pretty sure the gudgeon pin bosses are offset on the Accralite pistons on sale here for the 500 Bullets - I am sure the flat areas fore and sft of the gudgeon pin bosses have more flat area one side of the hole than the other, but you can't go wrong with them anyway , due to the different sizes of valve cutaways. Regards, Paul.

[Dennis C]

There you go, I learned something new today,

[Bullet Whisperer]

This has just reminded me of an Ariel Square 4 engine I rebuilt a few years ago - all four new pistons were marked with 'front', but it was stressed in some instructions I was given by the owner that the rear pair of pistons' 'front' actually faced rearwards, so the fronts of the rear two pistons went in facing rearwards, because the rear crank rotated in the opposite direction. Makes sense when you think about it !

[PeteF]

A day without learning is a day wasted (as my old used to say)

[Ginetta lad]

Well as I suspected 2 people working for our host were clearly wrong even though they argued for some time that the barrels are oval not the piston????
LIKE me My engineer contact said he was talking cobblers. So I've ordered a new 535 piston and he'll bore my barrel ROUND!!!

H

[Dennis C]

Glad we got that sorted then H, just don't let them use you nice shiny new piston to hone the bore with. ;-0

[papasmurf]

Suggested reading:- http://www.enginebuildermag.com/2004/05 ... finishing/