What should the compression reading be on a motorcycle engine?
Interpretation of Motorcycle Engine Compression Test Result: (1) The final result should be between 125 to 150 PSI per cylinder (refer to your motorcycle service manual for a more precise specification), and (2) On a multi-cylinder engine, the reading for each cylinder should be within 10 PSI of any other cylinder.
Can you do a compression test on a hot engine?
Further troubleshooting or narrowing down of the culprit for low compression seems like a waste of time. Note that doing the test on a hot engine would likely result in a few more PSI (~5% higher give or take), but doing the test on a hot engine is obviously problematic (very easy to burn yourself).
When does compression return to 120psi or higher?
If you have some light cylinder wall corrosion the compression may return to 120psi+ after you’ve run the motor a bit, so go easy on it for the time being.
What should the compression reading be on a 951?
110psi on a 951 is not terrible, it’s at the lower end but acceptable. On a DI there’s a little different procedure for taking a compression reading, not sure what it is but I’m pretty sure you don’t open the throttle full. Take a look in the service manual.
How to run a compression test on a fuel injection system?
WARNING: GROUND THAT PLUG WIRE TO PREVENT MODULE DAMAGE, OR WHEN EQUIPPED WITH A COIL-ON-PLUG IGNITION, SIMPLY DISCONNECT THE COIL HARNESS PLUG. Disconnect the injector for that cylinder on a port fuel injection system. Install your compression tester in the suspected cylinder.
When to do a compression test on a car?
Begin with a normal (“static”) compression test on a warm engine to eliminate obvious problems such as badly worn rings, burnt or bent valves or holes in pistons. If you have a diagnostic trouble code, you may know which cylinder is misfiring, but it’s a good idea to test the compression of all the cylinders in that bank to get a good comparison.
What are the advantages of running compression tests?
The advantage of a running compression test is that it gives you an idea of the volumetric efficiency of each cylinder. In other words, how efficiently each cylinder is pulling air in, retaining it for the correct amount of time, then releasing it into the exhaust. If a cylinder cannot perform these functions properly,…
What should the compression be in a snap throttle test?
Sample Test Readings. Comparing measurements between cylinders is important. Running compression at idle should be 50-75 PSI (about half cranking compression). Snap throttle compression should be about 80% of cranking compression.