It sounds like your valves are out of adjustment, take off valve covers and check intake .005 exhaust .007 at top dead center then turn 1/4 inch to right to get past compression release.
To adjust get one cylinder at a time to top dead center on compression stroke then turn engine 1/4 inch to right, loosen jam nut and put feeler gage between valve and rocker tighten till you are against feeler gage but can still slide it back and forth tighten jam and recheck.
If you have never done it you might have to try a couple times till you get "feel" of adjusting.