Stormin 9,975 #1 Posted July 16, 2019 As the title suggests, I'm having problems getting my C-125, (12hp) to idle properly. Check everything from tank to carb. New inline filter. Fuel getting to carb. Swapped air filters with the Black Horse. Even fitted another carb. Swapped spark pugs. Checked point gap. I can leave it on a fast idle and it will run for so long then start to die. If I can catch it by opening the throttle before it dies fully, it will pick up and rev freely. The only thing I haven't tried is changing the fuel pump. What I'm thinking, is it on it's way out. Pumps fuel ok when the revs are up, but not enough at idle. Any thoughts, anyone before I try a pump of another horse? Share this post Link to post Share on other sites
oliver2-44 8,852 #2 Posted July 16, 2019 (edited) Could it have an air leak between carb and block? Sray some starting fluid or carb cleaner around the outside and see if it rev's up. If it doesn't then the fuel pump seems like the next place to check. Edited July 16, 2019 by oliver2-44 Share this post Link to post Share on other sites
Pullstart 59,733 #3 Posted July 16, 2019 I had cleaned points a plenty, but not until I put new in did I realize how much nicer a couple of the horses ran. It may help to try a new set, if the pump doesn’t clear it up. 1 Share this post Link to post Share on other sites
Stormin 9,975 #4 Posted July 16, 2019 (edited) Points were new when I rebuilt the engine earlier this year. Edited July 16, 2019 by Stormin 1 Share this post Link to post Share on other sites
953 nut 51,721 #5 Posted July 16, 2019 Have you checked the ignition timing? A timing light or static timing will let you know if the points are properly adjusted. Share this post Link to post Share on other sites
Stormin 9,975 #6 Posted July 16, 2019 Timing is fixed I think. Share this post Link to post Share on other sites
Stormin 9,975 #7 Posted July 17, 2019 Fitted another pump today. Ran a tad better but not as I would like. Re-tuned the carb and things improved. Still can't get it to idle as slow as the Black Horse but I can live with it. For now. Share this post Link to post Share on other sites
pfrederi 17,147 #8 Posted July 17, 2019 Be aware Kohler recommends idle speed of about 1,200 rpm. Splash lube and cooling.... Share this post Link to post Share on other sites
Stormin 9,975 #9 Posted July 17, 2019 Thanks but I'm aware of that. Share this post Link to post Share on other sites
stevasaurus 22,230 #10 Posted July 17, 2019 Norm, the points gap changes the timing on these engines. It is recommended gap at .020. Check and make sure that is what you have. If so, try changing it to .018. Some of my older horses like .018 better then .020. Share this post Link to post Share on other sites
Stormin 9,975 #11 Posted July 17, 2019 Thanks Steve. I'll maybe try that tomorrow. Share this post Link to post Share on other sites