So here's where an extra piston helps to square the ring in the bore. Keep in mind where your pins are. Like I said before, on the MS 360 the bottom pin falls onto the left side of the intake roof as you look towards the chamber. I keep this side a bit rounder. Most intake flow occurs on the floor anyway.
Draw a line on the intake skirt at the degree you want. On the 360 I want 78*. So turn the wheel to 78 and mark the skirt.
Measure your difference between the line and skirt.
Mark that difference from the center of your intake floor towards the base. It's best to make that amount smaller and sneak up on the degree you want. You can always take more out, but you can't put it back in.
Put a ring in and draw your lines for your roof and floor. Write which side the bottom pin is on in the bore. Be careful there.
Grind your port. Take the center of the bottom first. Double check the degree you're at. When you've got it right, finish the port.
Smooth the port towards the opening. Be careful not to grind through the area where the neck meets the jug or any threaded intake holes, like the husky 262. The Stihl 046 has a notoriously thin flywheel side neck. I mark it with sharpie first so I rember not to touch it while blending.
Here's a stock 044 10mm, then a roughed in port, then a finished chamfered one.
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Dolmar 421 6 port, but open
