how do i tell if i need a "b"piston or what when the pistons i have taken out of my engine do not have any markings on them.
and do i buy my mc28 piston kits from tyga which i am led to believe that they will fit my mc16 engine.
please correct me if im wrong.

There should be a marking on the rear base of the cylinder saying A, B or C. You can use this marking as long as the cylinder has never been replated. If it has then you need to measure the cylinder bore (with a bore guage), work out what clearance you want to run and then calculate what size piston you need to order.
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If I have to take the carbs off once more...

Here's how to match up cylinders and pistons.

A Cyl = B piston
B Cyl = No mark piston
C Cyl = D piston
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thanks guys now just to see if my local honda dealer can get them for me!!!!!!!!!!!!!!!!!!!!!!!!!!!