compression spec for yamaha 55 1993

schmalts · #1 September 29th, 2009, 11:09 PM

Hi, anyone have the compression spec for a yamaha 55hp 1993 model? that is the 2 cyl model. I am thinking of buying one but want to test compression before I buy.
any thoughts on the reliability of these motors?

JB · #2 September 30th, 2009, 09:36 AM

There is no psi spec, schmalts.

Look for the cylinders to be within 10% of each other. Depending on your guage, technique and conditions you might get as high a 120-130 or as low as 80-90.

Good luck.

robert graham · #3 September 30th, 2009, 10:13 AM

Always a good idea to run the motor on the boat, in the river, before buying it. Run it wide open for a few minutes, then at mid-range, then at idle. If it does all these well, then it may be a good motor. Good Luck!