Hello, my nasme is Cory
The compression is 3 bar?
You need at least 9 bar or 110 psi to run
So does that mean overhauling the whole engine or just the head and regrinding the valves first
First you must remove a plug and add an ounce of engine oil inside the cylinder. Then recheck compression. This is called a wet test
if the compression goes up, the rings are bad.
If the compression stays the same, you will then want to compress air into the cylinder with that particular cylinder at Top Dead Center or remove rocker arms to insure cam is not opening valves.
If the valves are leaking you will hear compressed air coming through intake or exhaust pipe or both
Are all the cylinders the same reading?