How much compression should a 2 stroke have?
between 90 and 110 psi
Normal compression is between 90 and 110 psi. Conclusion: You can follow the steps in this article to quickly diagnose all your two-cycle lawn equipment.
Is 90 a low compression?
They shouldn’t vary more than 10% from highest to lowest. That all said, 90 psi is too low, even for a low compression engine.

How much compression should a 80cc 2 stroke have?
To ensure effective operation on a dirt bike of 85cc, an 80cc engine should be compressed to 130 lb-ft. It is best to give 150-160 PSI of compression. Dirt bikes with 125cc-2 engines do better with 140 PSI and an average top-end of about 180.
How do you fix low compression on a snowmobile?
In this case, you want to perform a compression test on each cylinder in your machine’s engine….Fortunately, you can manually clear the line using these steps:
- Hit the kill switch.
- Pull the spark plugs.
- Hold the throttle open.
- Pull the starter cord 15-20 times to clear the line.
- Wipe off the spark plugs and replace them.
What is a bad compression reading?

So, as a general rule a compression of 135 PSI or better, is excellent. On the other hand, a compression of 85 PSI or lower, is extremely bad. Firstly, the most desirable situation is that all cylinders, give the same or close to the same reading. In addition, that reading should be, above 135 PSI.
What is bad compression?
Low compression is bad news because it means your car is suffering from an internal engine issue—and that almost always leads to a hefty repair bill. The root cause of the problem could be one or more costly repairs, ranging from worn-out piston rings to a blown head gasket.
What should the compression be on a 50cc 2 stroke?
A 50cc, 60cc, 80cc, 100cc, 125cc 200cc or 500cc should be able to squeeze out a reading of 120-190 PSI. A 250cc should be in the neighborhood of 170-240 PSI.
How do you increase compression on a 2 stroke?
Remove the cylinder head, under the head, sitting on top of the liner there should be some shims in the form of rings. There may be just one or several. Reducing the thickness of this shimstack will give higher compression. On an average sport type engine you will notice little if any difference.