QuestionQUESTION: Hello, I recently took a B & S 14.5 hp 287707 OHV engine apart. After I got it put back together and tried to start it, it backfired and sheared the flywheel key. I replaced the flywheel key and it did it again. I was careful to line up the dots on the crankshaft and timing gear but is it possible to still be out of sync? I really didn't pay any attention where the piston was when I put it back together, I didn't realize it could make a difference. Thank you.
It ran fine after I replaced the sump gasket, a previous question, but I had to take it apart when I thought the rod broke. turned out to be on top, magnets came off the flywheel.
ANSWER: Hello Again Dave:
The Matching of the Timing Marks will Set the Piston to the Proper Location in the Cylinder and Time the Valves. If you have the Proper Flywheel, then Recheck the Timing Marks. Are you Torquing the Flywheel Nut to 150 Foot Pounds? Did you Set the Valves Correctly? I Do Not Use the Setting Called for by the OEMs. I have Found that the Following Works Best. Remove the Valve Cover (on the Dead Cylinder for Twin Cylinder Engines). Set the Cylinder you are Setting the Valves on to Top Dead Center (Both Rocker Arms will have Play in them when the Engine is at TDC) When Setting the Valve Clearance. Now Loosen the Valve Adjuster Locks and Set the Intake Valve Clearance to .003in -.005in and the Exhaust to .008in - .010in. I have had Better Performance Out of the Mowers and Less Burnt Valves Using these Settings. Hope this Helps. I am Here if You Require More Assistance. Let me Know What Happens, Please. Thanks.
Good Luck
Respectfully
John
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QUESTION: Hello,
Thank you for the information. The flywheel was the original, I re epoxyed the magnets back in position. I set the intake valve to .004 and the exhaust valve to .009 replaced the flywheel key and cranked the engine. It fired and sheared the key again. I had one key left so I cleaned the crankshaft, cleaned the flywheel hole and used a 1/2 drive to tighten the flywheel bolt. I don't have a torque wrench but I used a pipe wrench on the output side to hold the pulley and cranked the daylights out of it. I replaced the key, turned the key and it started right up. There is surging and uneven running but the fact that it runs demonstrates that the timing is OK as far as the crankshaft relative to the cam shaft. I think the problem now is the carburetor causing the uneveness. Thanks for your help, I appreciate it.
ANSWER: Hi Dave:
Great!! People Misunderstand the Purpose of the Flywheel Key. It is Not to Hold the Flywheel; it is To Time the Plug Firing to the Piston Location During the Power Stroke. The Wedge Fit and Torqued Nut is What Holds the Flywheel Onto the Crankshaft. That is Why the 150 Foot Pounds of Torque. The Surging Does Sound like the Carburetor. Hope this Helps. Till Next Time. May All Your Mechanical Problems be SMALL ONES and May the All Mighty Bless You and Yours. Thanks Again.
Best Wishes and Good Luck
Respectfully
John
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QUESTION: Hello,
When it is running, if I pull the choke a little it smooths right out. I know this is an important clue. So when the choke is in the off position it is starving for gas? I'll have the manual for next time, I appreciate your help, Thank You.
Dave
AnswerHi Dave:
It Does Sound like the Main Jet is Restricting the Gas Flow and you are Assisting the Carburetor by Applying the Choke. Remove, Disassemble and Soak the Carburetor Overnight in Carburetor Cleaner (I Use Gunk). I have Found that Most People can Use a Breakdown/IPL and Disassemble the Carburetor Enough for Proper Cleaning. You Only have to Remove the Bowl, Float Pin, Float and Needle Valve and Any Adjustment Screws that Go Into the Carburetor Body. The Welch Plugs Do Not have to be Removed. Then Soak the Carburetor Body and Parts in a 1 Gallon Can of Gunk Carburetor Cleaner Overnight. The Can has a Parts Tray Inside it for the Small Parts. Once the Carburetor and Parts are in the Cleaner, you can Replace the Lid for Safety and to Prevent Accidental Spillage. Then Blow Out the Passages with Compressed Air. Install New Parts if Required. Hope this Helps. I am Here if You Require More Assistance. Let me Know What Happens, Please. Thanks.
Good Luck
Respectfully
John
