Kohler engine issues

[6wheeler 603]

Hi all. I have a situation I am having a tough time with. This could technically go into "Other Brands". But, since it is an engine issue. I thought it should be here. Moderators please move this if need be. So, on to the Engine. It is a Kohler 25 hp. CH25S Vertical V-twin. Spec.# 68529. The problem started while I was mowing with the machine (It is a Scheiss 6025 zero turn). All was fine and then it lost power and started to run on 1 cylinder. I brought it into the shop and after it cooled down I did a plug test and found it wasn't firing on the left cylinder (from the fan side). I checked the coils and found 1 was very weak/dead. I ordered new coils and replaced them both. It was spitting gas back through the carb also. I did a compression test on both cylinders and Non-oiled it had 134 and 136 respectively.  Now, with the new coils in. The spark on the right cylinder (from the fan side) is bright. The left spark is consistent. But, not as bright as the right side. Now here is my stumper. The engine still won't throttle up. It sound like it has a light miss. Running for only less than a couple minutes like that? It turned the left side (from the fan side) exhaust pipe onto the muffler cherry red while the right side(which I am sure was hot too) stayed normal. Any Ideas? All I have done on this is change the coils so far. Any help is appreciated.   Thanks   Pat 

[wallfish 16,999]

On 7/31/2024 at 12:28 PM, 6wheeler said:

Hi all. I have a situation I am having a tough time with. This could technically go into "Other Brands". But, since it is an engine issue. I thought it should be here. Moderators please move this if need be. So, on to the Engine. It is a Kohler 25 hp. CH25S Vertical V-twin. Spec.# 68529. The problem started while I was mowing with the machine (It is a Scheiss 6025 zero turn). All was fine and then it lost power and started to run on 1 cylinder. I brought it into the shop and after it cooled down I did a plug test and found it wasn't firing on the left cylinder (from the fan side). I checked the coils and found 1 was very weak/dead. I ordered new coils and replaced them both. It was spitting gas back through the carb also. I did a compression test on both cylinders and Non-oiled it had 134 and 136 respectively.  Now, with the new coils in. The spark on the right cylinder (from the fan side) is bright. The left spark is consistent. But, not as bright as the right side. Now here is my stumper. The engine still won't throttle up. It sound like it has a light miss. Running for only less than a couple minutes like that? It turned the left side (from the fan side) exhaust pipe onto the muffler cherry red while the right side(which I am sure was hot too) stayed normal. Any Ideas? All I have done on this is change the coils so far. Any help is appreciated.   Thanks   Pat 

Just taking a stab at it from the clues in red above. I'm unfamiliar with those engines

Clogged Exhaust / Muffler ?

Edited August 1 by wallfish

[6wheeler 603]

Problem Solved. For anyone else that may get one of these. Being a vertical. Or, horizontal. The engines that Kohler made with the Smart Spark ignition. Whether it be the DSAM or DSAI ignitions. The control modules failed with no replacements available. However, Kohler makes a kit to install for about $200. That converts the crappy digital stuff with an original MDI ignition. The kit includes a new flywheel, coils. And, all the wiring and connectors to install. Plus, good instructions on how to do it. Outside of the tear down to do it? It is a very easy install. These engines were used by Toro, Scag, And Exmark. Plus many other machines. Known by the CH and CV series. But rest assured, If your Kohler C series engine starts to miss and spit gas out of the carb? More than likely? It will be an ignition issue if it is a Smart Spark engine. After this kit?  My engine is now running very well. Seems like it has a lot more power. And? a new thing. It does NOT like choke. I used to have to choke it to get it to start no matter the temp. No more.