QuestionJohn, Forgive me, I am having problems getting into Eric's queue. Would you perhaps have an opportunity to review the below?
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Followup To
Question -
Hello,
First, Thank you Very much for providing this service. It is very much appreciated, plus it looks like you are pretty popular.
Replaced a piston in my craftsman rider. Ensured gears were lined up dot-dot. Everything internal was fairly straightforward. Only confusion was how the governor slinger should be installed. I installed it with the retractable pin right against (Not on either side) the gauge extending inside the housing. Other side over the Cam, no spring clip or anything. Oil pan housing resting on top of that.
Buttoned everything up. New starter, new magnatron and battery and plug. Sucker spins like a top, but will not start. Got gas, spark and air. When choked, it will backfire through the air cleaner, but no joy. Not sure where to start next. Carb maybe get gunked while getting spun around or do you think I screwed something up internally? Man, I hate to screw up a new set of gaskets...
Much Appreciated
Answer -
Just to confirm the governor system. When you re-assemlbed the engine, the oil slinger/governor should have sat on top of the camshaft. The end of the oil slinger/governor should have been resting on the governor arm paddle inside the engine block.
<MZ> Correct, This makes me feel better. It is installed as you describe.
Did you remove the valves or valve tappets when replacing the piston?
<MZ> tappets only. Noticed that they were the same size, so no problem with mixing them up.
Did you rotate the engine by hand before buttonening up the engine and follow the engine strokes to ensure the mechanical timing was correct?
<MZ> Yes, I wanted to ensure that the pison rod connecting cap bolts cleared, which they did.
Did you remove the flywheel or crankshaft when replacing the piston?
<MZ> No I did not. I did as little "fooling" as possible.
Is the piston connected to the connecting rod correctly? What are the valve stem to valve tappet clearances?
<MZ> Piston is connected per directions and torqued. Valve tappet clearance I did not check. Just reinstalled Cam shaft the same was as I found it.
A dirty carb can cause the problem but it sounds more like a timing issue. A sheared flywheel key will cause ignition timing errors and incorrect valve gap can cause mechanical timing errors.
Let me know so we can narrow down the problem.
Eric
<MZ> Thanks again for assisting. Tonight I blew the carb out, now getting a nice fine mist. Also I pulled the cylinder head and spun the flywheel and followed all the strokes. Incoming valve opens nicely, piston travels down as it would when pulling in the mixture, Incoming valve then shuts, compression upstroke occurs fine, figure out when the spark should happen, both valves are closed at that point, piston travels down, then exhause valve opens nice and wide for the exhause stroke. Not sure about the flywheel pin or valve clearances, from sight, the valves "appear" to be OK, which direction do you recommend pursuing?
Highest Regards,
Answer Hello Mark:
From the Description of your Problem I Suggest you Check the Valve Lash and If the Valve Lash is Correct, then Remove the Flywheel and Check the Flywheel Key. The Key can be Damaged by the Engine Coming to a Sudden Stop. The Intake Valve is Either Not Seating Due to Improper Valve Gap or the Flywheel Key is Damaged and Causing the Plug to Fire Just Before the Intake Valve Closes. To Check the Valve Lash; Turn the Piston to TDC. Remove the Carburator and the Crankcase Breather/Vent. Using a Blade Feeler Gauge Check the Clearance Between the Tappet and the Valve Stem. Intake Valve is .008 - .010in and Exhaust Valve is .012 - .014in. Some Models have a Compression Release and are Set at Intake .002 - .004mm and Exhaust .005 - .007mm. Hope this Helps. I am here if you Require more Assistance. Let me know what Happens, please. Thanks.
Good Luck
Respectfully
John
