I have a Sabre 17.542HS with a Kohler CV491S-27509 motor. It starts fine and idles smooth. When I put it at full throttle it seems to have a miss and has very little power. The rpms are also not up like they were just a couple weeks ago. When I engage the mower deck it almost stalls completely. I have changed the fuel filter, fuel, oil, oil filter. Cleaned the carburator (no gunk found). I also pulled the head off and checked and cleaned the valves and lifters (again no issues found). When reassembled it ran the same as before I took it apart. so no change.
You could have a weak coil and misfiring under a load each cylinder has it own coil on that engine you can get a inline spark tester to see
This engine only has one cylinder. Would the weak coil still let it idle smooth?
Ok Tested with the inline spark tester. The spark is good and bright. Nice and steady at full throttle and slows down at idle.
a dirty jet inside the carb would cause rough running
Well I just got done cleaning the carburator. Still the same. Still runnining beautifully at an idle. But when I put the throttle lever up to full it has no power and sounds like ****. It looks like it blows a air and a little fuel out the carb. I know it sounds like the intake valve. But why would it only be at full throttle? It seems like my next option is to have the valves reground and replace the push rods and lifters.
I don't know if this is any help but I checked the compression and it is 60. I don't have a leakdown tester so can't do that test.
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Ok After loosing half the hair I had left. I broke down and took it to a local service shop. Well He found the problem. It turns out the exhaust lobe on the cam collapsed/wore down to pretty much nothing. So now it is just a matter of saving the money and getting the new cam, gaskets and lifters. Then it should be good to go.
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