akooter

I'm a previous owner of a 1988 GSXL, sold it after I got married. Looking at buying a 87 Sport as a project and occasional driver. Just curious if compression test results really tell the story about a rotary? If maintenance was poor in the past, will that show up in the compression test? Or, what are the things I should look for to confirm that the powerplant and drivetrain are still good?

menace

the compresion tels the story for the engine...

im nt sure hw u would check yhe driveline tho...

(make sure there arnt any funny noises as u drive..)

vaughnc

So long as it's the rotary specific compression test (best from the dealership) it will definitly let you know how the apex seals are doing.

From what I've seen, compression will drop pretty linearly until the seals eventually do go.

Note low compression does not mean loss of power like in a piston engine.

At 96K miles my compression numbers on the NA convertible were 75% of optimum which is about right

Supraman90

What is the optimum compression for NA anyways? i am looking to buy a '88 GXL and it has 70psi across the board.

1987RX7guy

iTrader: (3)

Supraman90


If that is on a proper test its bad.

J-Rat

iTrader: (2)

Yup, FSM specifies 85 PSI. That is at 250 RPM on the starter.

Jarrett

Dan H

It only tells part of the story. An oil seal can give out later on but yield excellent compression numbers for example.