jchamberlin
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- Jul 19, 2010
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- Jeremiah Chamberlin
Don T: I hope you read this before you get back to wrenching. You should be able to verify Top Dead Center (TDC) for the piston in the cylinder versus the timing mark on the cam very simply in a Kohler (but it will work for any engine, if you're careful).
1. Remove the spark plug
2. Insert pencil or some other non-ferrous item that is stiff enough to indicate the position of the piston in the cylinder, but supple enough not to break and/or damage the top of the cylinder (tricky with engines in V-configurations and/or angled spark plugs, but easy in a Kohler)
3. Turn crank by hand until the piston has achieved it's apex (highest point).
4. If in doubt about the highest point, you can fine-tune the procedure by turning carefully until the piston reaches its highest point, make a mark; continue turning until the piston starts to move down again, and make another mark. Top-Dead-Center will be midway between the marks.
Before you start, you may want to get the "S" or "T" in view through the window, because it is possible to locate TDC between the Exhaust stroke (up) and the Intake stroke (down); when what you want is to locate TDC between the Compression stroke (up) and the Power stroke (down).
I'm not an engine expert like Harry describes, but I remember going through the process when I degreed a cam. And yes, if you're hearing backfire through the carburetor, then the timing is too far advanced. I'm not versed enough in Kohler's to know if that means the spark gap is too large or too small, but judging from what you've been through (and trust me, I feel for you), it would probably be a good idea to re-establish a baseline. A simple "pencil test" should tell you if turning wrenches is required or if you need to look elsewhere (again).
Edit 1: Get the "S" mark in view before you begin, that should put you at a point BTDC (Before Top Dead Center).
Edit 2: I forgot to state the purpose of the test: If you locate TDC with the pencil test, the "T" should be at or near the viewing window. If you're close to the "T" when you have independently located TDC, then you don't need to open it up; if "T" is not in view at TDC (or further from it than you think is right), then you need to open it up to confirm cam alignment. (Didn't you do this once before on this motor, or was it someone else?)
1. Remove the spark plug
2. Insert pencil or some other non-ferrous item that is stiff enough to indicate the position of the piston in the cylinder, but supple enough not to break and/or damage the top of the cylinder (tricky with engines in V-configurations and/or angled spark plugs, but easy in a Kohler)
3. Turn crank by hand until the piston has achieved it's apex (highest point).
4. If in doubt about the highest point, you can fine-tune the procedure by turning carefully until the piston reaches its highest point, make a mark; continue turning until the piston starts to move down again, and make another mark. Top-Dead-Center will be midway between the marks.
Before you start, you may want to get the "S" or "T" in view through the window, because it is possible to locate TDC between the Exhaust stroke (up) and the Intake stroke (down); when what you want is to locate TDC between the Compression stroke (up) and the Power stroke (down).
I'm not an engine expert like Harry describes, but I remember going through the process when I degreed a cam. And yes, if you're hearing backfire through the carburetor, then the timing is too far advanced. I'm not versed enough in Kohler's to know if that means the spark gap is too large or too small, but judging from what you've been through (and trust me, I feel for you), it would probably be a good idea to re-establish a baseline. A simple "pencil test" should tell you if turning wrenches is required or if you need to look elsewhere (again).
Edit 1: Get the "S" mark in view before you begin, that should put you at a point BTDC (Before Top Dead Center).
Edit 2: I forgot to state the purpose of the test: If you locate TDC with the pencil test, the "T" should be at or near the viewing window. If you're close to the "T" when you have independently located TDC, then you don't need to open it up; if "T" is not in view at TDC (or further from it than you think is right), then you need to open it up to confirm cam alignment. (Didn't you do this once before on this motor, or was it someone else?)
