Hp4 Fitment query

Just took delivery of HP4, Theres grooves in the centre for woodruff key. Noticed small arrow on plastic fanwheel aswell.
With thearrow facing upwards which groove do I use for the PX200.

mikem use the groove at the top the one shaped like a starfish i,ll show you in the isle of man if you want[:D] ;D [:D] [:D] ;D [:dance3:]

SHOUT GOIN OUT TO THE ITALIAN BOBSLEIGH TEAM

Don’t think the party in question was too impressed with that especially when his ignition fell apart[:roll:]

mikem, better make sure you take plenty of 2-stoke oil to lube that piston[:smokin:] [:shock1:]