Compression on 1973 135HP Evinrude

[Oct7brian]

Could someone tell me what I should have for compression on my 1973 135 HP evinrude also its a xflow when installing the pistons could someone tell me which way they are installed .... there is a sudden slope that droped very quickly on the piston surface and on the other side the slope starts about where the plug makes contact and contunies the the edge of the piston. Currently the large slope it towards the exhaust port I just wanted to make sure they were installed correctly. Anyone that can help would be great THANKS!!!

 

[Walker]

Re: Compression on 1973 135HP Evinrude

The sudden slope goes to the intake ports and the long slope to the exhaust ports. There are also small holes in the connecting rods at the wrist pin end. Those holes must face up.

 

[walleyehed]

Re: Compression on 1973 135HP Evinrude

The crown of the piston has a straight side and a half moon side.<br />The straight edge faces the center of the engine (exh), the half moon is on the intake side (more fwd.)<br />Compression figures should be within about 5% of the average of all 4. I would guess they should be in the range of 100-120lbs. REMEMBER it's more important they all be "about" the same.