I am at my wits end. I hope someone can shine some light on this one for me. The engine sputters or skips periodically like it noticeable hiccup. Engine specs: - Tecumseh 9HP - Model HMSK90 - Float bowl carb - Snow blower is about 15 years old. and doesn't blow any smoke this engine has the easy start option This is the list of things I have done so far to the engine. - Changed oil 5-30 - New spark plug J19LM gap set for .030 - Rebuilt carb with kit so it has new gaskets and metering valves set bowl float 11/64 - Prior to carb rebuild, let the whole thing soak in the ultrasonic cleaner for multiple rounds and got it spit shinny clean. - Replaced crank seal - Ground down valve stems (before less than .002 in), now both .008in. Specs call out .012in for the exhaust. I thought the exhaust valve would solved this problem because it appeared it was not seating flush so I lapped that valve as well as the intake. After inspecting the faces of both valves, it would appear they were contacting the valve seat evenly. I was so sure this would have done the trick but now I am back to square 1 - Replaced head gasket, Torqued to specs. This is some additional information which might help. On a high rev (no load) you can hear the engine skipping. At a lower rev or idle (no load), it tends to skip a bit more. Once you put a load on the engine the skip doesn't go away completely but is noticeably less frequent to almost not at all. As soon as the load is off, it begins skipping again. I did spray for carb leaks with carb cleaner but that didn't turn up anything. Oh, not sure if this is related but when I move the throttle from high speed to idle, it is not instant. I am now leaning toward the possibility of week valve springs. Any ideas ? Dan

Thanks for the reply supermootch. Maybe I am wrong but, I was not aware these small carbs could be rejetted. The rebuild kit contains the float bowl gasket, float bowl nut whch has the idle metering screw, the main jet metering screw with the washer and the bowl valve with the new bowl valve seat. No jet included.

You may be on the right track with the carb issue though. The variance on the main jet and the idle just appear to be a bit wide. If I turn out either screw about 4-5 turns in the perspective modes, the engine should stall and it doesn't at times.

I had put this carb through its paces with the ultrasonic cleaner, and blew out all the orifices with forces air and sealed the welch plug with gasket sealer just incase. I did all the stuff I was supposed to do ....... that is why I am frustrasted with this now. It should be running like a champ and it is not.

Fixya is not very clear on how to start a new session so I ended up under the heading for the 5 HP Tecumseh where the engine I am currently working on is a 9HP. Thanks for the reply supermootch. Maybe I am wrong but, I was not aware these small carbs could be rejetted. The rebuild kit contains the float bowl gasket, float bowl nut whch has the idle metering screw, the main jet metering screw with the washer and the bowl valve with the new bowl valve seat. No jet included. You may be on the right track with the carb issue though. The variance on the main jet and the idle just appear to be a bit wide. If I turn out either screw about 4-5 turns in the perspective modes, the engine should stall and it doesn't at times. I had put this carb through its paces with the ultrasonic cleaner, and blew out all the orifices with forces air and sealed the welch plug with gasket sealer just incase. I did all the stuff I was supposed to do ....... that is why I am frustrasted with this now. It should be running like a champ and it is not. Fixya is not very clear on how to start a new session so I ended up under the heading for the 5 HP Tecumseh where the engine I am currently working on is a 9HP.