If the mower still has its original engine then OP can't adjust the valves since it is a Kohler CV15 with hydraulic lifters.Possibly, may need to adjust valves with engine cold, post all engine information, make & all information from data plate.
post all engine information, make & all information from data plate.
If Kohler engine no valve adjustment, hydraulic lifters, see troubleshooting section 3.1 in manual above.yes iFree Kohler Service Manual Downloads - OPEengines.com
Listed below are Kohler engine service repair manual in Adobe PDF format that you can download for free. Below we have provided a link to these manuals which can also be download. Click on your engine listed below to download. These service manuals provide general information, adjustment...www.kohler-engine-parts.opeengines.com
yes it is a 15hp kohler cv15s-41618If the mower still has its original engine then OP can't adjust the valves since it is a Kohler CV15 with hydraulic lifters.
Here is a question has the OP a shot fuel in the carburetor to see if it is a fuel problem or other problem?