wiseco piston

[amp0317]

I am going to put a Wiseco piston in my 400. its standard bore, 11:1. Piston came but does not have the IN marked on it, only an arrow. Arrow is pointing outwards towards rings. For installation, does the arrow point toward the intake or exhaust?

[zrpilot]

I'm 90% sure it is pointed towards the exhaust side

[JOEX]

I always thought the arrow pointed in the direction of the flow.

Could be wrong though:p

[GPracer2500]

The arrow points to the exhaust.

When in doubt: with four stroke pistons that have reliefs cut into the dome for proper piston-to-valve clearance, you can determine the piston's orientation by matching the reliefs' size to the valve sizes. Intake valves are almost always a larger diameter.