Re: Correct Piston Ring Size 1966 Merc 650 65 HP
you need to post your engine seriel #. also you will ned to measure the current bore size. its possible its been bored oversize from standard. the piston rings come in standard bore size(2.875),+.015"(2.890), and +.03(2.905). pistons come in the same sizes.<br /> the ring compressors are difficult to find now. <br /> if you cannot find them its possible to use a pair of very dull blunt screwdrivers or butter knivess. its difficult and requires someone to spend a long time holding the crank above the block but not impossible. when all pistons are in take a small screw driver and go through the intake ports and depress each ring. if it springs back its ok if it does not it was broken on installation and the procedure gets repeated.<br /> use the search feature on this forum for clams email.
<br />Help.. <br />We have taken our entire motor apart due to having to fix a burnt piston.. We ordered new rings due to a couple of the other's breaking.. The wrong size was given.. Old Merc.com has 3 different parts numbers for a 650.. We already have 39-45153A12.. They are too big.. What would be the correct ones? Old Merc didn't know... We are also unable to get the piston back into the powerhead without "special" tools.. Can only find 3 and they won't fit our piston size ( 2 13/16).. Please Help with this as my husband is now going to sell it out as parts after replacing many different things... Thanks Kelly
