What should the compression be on a motorcycle?
Generally speaking, a motorcycle with around 100 PSI compression in its cylinders will likely need a rebuild very soon. Anything less than 100 PSI is going to have issues running, if it can even start at all. Most healthy motorcycle cylinders should read at least 110-120 PSI. All readings should be about the same.
What’s the minimum psi for a compression test?
The first thing I do, when a non running bike comes in, is to run a compression test. If the engine does not have at least 100 PSI (Pounds per Square Inch) in each cylinder, I won’t work on it, except to rebuild it. It would be a waste of the customers money if I “Tried” to make it run. 100 PSI is the minimum.
Can you do a compression test on a cold engine?
A warmed up engine will give you a more accurate reading, but you can run a compression test on a cold engine. A good test will result in decent compression/PSI. Your shop manual should specify the exact readings for your bike. Additionally, you’ll want all of the cylinders to be within about 10 PSI of one another.
Why does my motorcycle compression test come back low?
If the readings come back higher than the original compression test, the low compression is likely due to the rings. If the readings don’t change, it’s likely due to your motorcycle’s valves. If your valve clearance is too tight and not set properly, it could be causing the low readings.
Generally speaking, a motorcycle with around 100 PSI compression in its cylinders will likely need a rebuild very soon. Anything less than 100 PSI is going to have issues running, if it can even start at all. Most healthy motorcycle cylinders should read at least 110-120 PSI. All readings should be about the same.
How do you test compression on a dirt bike?
Hold the throttle wide open (twist the throttle all the way back). Kick the kick-starter over quickly with 5 strong kicks (only test on a cold engine that hasn’t been run in the past 6 hours). Check the compression PSI number of the tester gauge. It’s really that simple to test the compression on your dirt bike.
The first thing I do, when a non running bike comes in, is to run a compression test. If the engine does not have at least 100 PSI (Pounds per Square Inch) in each cylinder, I won’t work on it, except to rebuild it. It would be a waste of the customers money if I “Tried” to make it run. 100 PSI is the minimum.
A warmed up engine will give you a more accurate reading, but you can run a compression test on a cold engine. A good test will result in decent compression/PSI. Your shop manual should specify the exact readings for your bike. Additionally, you’ll want all of the cylinders to be within about 10 PSI of one another.