Small Engine Troubleshooting Problems? Ask a Mechanic Now.
Welcome to JUST ANSWER small engines, let me try to help you !! I don't know it all, but maybe together we can get you a satisfactory answer!
Kohler engine? Model number? Do you have a voltmeter to check the battery voltage when trying to start? What does the voltage drop to?
The 15 horse model is usually not hard to start. But it does have a compression release as part of the camshaft gear section. Do you have a compression gage to test the compression? If over 100 psi, the compression release may be broken, and causing too much compression, making it hard to start. But I would try adjusting the valve clearance at .004 inch. to see if it would help.