My 2 cents worth on problems with 25HP Kohler engines. If you have an older engine like I did and are tired of taking it to the shop on a regular basis, get a rebuild on your engine. I don't know why I didn't do it sooner. I had ongoing problems, (I won't get into specifics because they are too numerous to list), but finally had a rebuild and it has run like a charm ever since. It even sounds completely different. I had the option of going for a new engine, (have a Lazer 52"), for $1500 or rebuild for $750. Decided on the rebuild as my mower is several years old and I'll probably be in the market for a new one after this season. If you are unfortunate enough to have one of these problem engines that were manufactured a few years ago, do yourself a favor and just have it rebuilt. It's not worth the cost of constant repairs and hoping every time you get it back that everthing will be ok. Something else continues to fail time after time. Advice for what ever it's worth. Hope I can save someone with one of these problem engines from constant headaches, especially with the busy season coming up. P.S. I was so frustrated with my old Kohler I told the dealer I would not accept a rebuild if he used my old engine. I wanted a different one. He agreed to my request. My old engine would probably have been alright with a rebuild but I never wanted to see it again after all the problems.