I have stripped down a Ryobi/Homelite RY70133 (aka PLT 3043) 30cc trimmer.
Coming to reassembly, I don't know which way around to orient the piston with regard to the exhaust port. Conventionally, a piston would have an arrow mark on the head face, which points to the exhaust port. On this model however, there is no arrow - only a part number and 'B' stamped into the piston head face.
The other clue I hoped for was by looking at the location of the retaining pins in the piston ring grooves. These are offset by 28mm circumferentially, but both are on one side, i.e. the pins must straddle either the intake port or the exhaust port. The exhaust port is much wider than the intake, and measures 21.7mm wide (22mm circumferentially). That means there is clearance on either side of both the exhaust and the intake port for the piston ring gaps to sit without snagging. So, I have no clue which port the pins would face, because on this basis they could straddle either port.
Anyone know the proper answer?
Thanks
Ian from Australia
PS: this is my first post, so hi everyone, and special thanks to the dedicated efforts of the moderators.
