Since I bought this GS-R used and it had signs of a younger person owning and modifying it, I did a compression test today on mine to check out the condition of the rings and this is what I got:

Cylinder: 4 3 2 1
Test #1: 200 180 190 200
Test #2: 200 190 200 200

Now according to my service manual, the standard for the B18C1 is 270psi, low rating is 140psi with no greater than a 28psi variation between cylinders. By these standards, my engine "seems" to be in a healty state, but i'm not too keen on those compression numbers. When I did test the compression, on the first stroke the pressure shot up to like 150-180psi and then on each succesive stoke got a little high till about 200psi. I noticed that if I cranked it for 5 strokes instead of 4, I got a slightly higher reading of about 210-215 per cylinder. So what do you tech folks get from this? Sounds normal or does something seem a little off?

 

I should also mention, when I was testing #4, a noticed smoke emmiting from #3, not a super heavy amount but none the less, #3 was smoking. I used a teaspoon of oil in #4 to ensure I wasn't getting falsey low readings and it was after that when I saw smoke come out of #3. BTW compression in #4 shot u past 300psi in #4 when I did that, so I figured my rings were defintley not bad with such high numbers (compared with my '93's numbers).

 

Was the engine warm or cold when you did the test? Should be warmed up. Did you block the throttle open when you tested it? Could cause false readings. Did you disconnect the electrical clips from the injectors when you tested? What you saw coming from #3 was probably the result of fuel from the injector. Not good to have raw fuel squirting during the test. Messes the oil and can hurt the rings if done to excess. Raw oil in the cyl also will give a false reading. Makes a perfect seal. After all that, I think the compression sounds perfect.

 

I did everything except disconnect the injectors, which probably does explain why the smoke was there. Thanks!