wiseco piston in backwards

[3wheelerlouie]

i bought a couple of 250R airfooler engines (81 and 84 model) and both had wiseco pistons in it but the arrow was pointing to the intake.. if i remember right the arrow always points to the exhaust port , am i right ??? i am just curious on how these things were running with the piston in the wrong position.. does this cause damage to the sleeve ?? i removed the pistons and turned them around to where the arrow points to the exhaust ..

[toocheaptosmoke]

Regardless of arrows, the ring end gaps NEVER go on the exhaust port side.

[DixiePlowboy]

I got a friend's '86 YZ490 running one time, only to have it sieze within 15 seconds of run time. It had a fresh bore and new Wiseco..just as the previous owner told him... but in backwards. Turns out that the exhaust side of that particular piston would just barely uncover the intake ports...enough to keep it running, but not enough to lubricate it.