QuestionI have a craftsman riding mower w/21hp v-twin b&s engine. while on a slight incline on my trailer, I started it up but it was running rough. before I could get it off the trailer, it backfired and now it will not start. replaced the plugs, but did not help. any suggestions?
AnswerHello Mike:
>>Sorry for the Delay. This Question was Located in the Question Pool and I can Only Answer Questions from the Question Pool when I am Not Answering Questions here or at the Other Site I Answer Questions at.
>>From your Description it Sounds like the Flywheel Key Sheared, A Valve Rod has Jumped Off or the Head Gasket has Blown.
>>THINK SAFETY: Always Remove the Spark Plug Wire/s from the Spark Plug/s and Tie Away from the Spark before Working on Any Small Engine unless the Plug/s must be Connected to the Coil/s for Diagnostic Reasons.
>>I Suggest you Check the Valves First.
>>The Following is a Basic File I made for Setting the Valve Clearances. Any Input is Appreciated.
>>**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).
>>Check the Push Tubes and make Sure they are Not Bent.
>>Set the Cylinder you are Setting the Valves on to Top Dead Center on the Compression Stroke When Setting the Valve Clearance. Now Loosen the Valve Adjuster Lock and Using a Blade Style Feeler Gauge, Set the Intake Valve Clearance to (See Chart at Website I Provided) and the Exhaust to (See Chart at Website I Provided) Loosen and Tighten the Rocker Arm and the Feeler Gauge is Placed Between the Rocker Arm and the Valve Top where the Rocker Arm Pushes on the Valve.
>>***BE SURE TO TIGHTEN THE ADJUSTER LOCK AFTER YOU HAVE THE PROPER VALVE CLEARANCE***
>>I have had Better Performance Out of the Mowers and Less Burnt Valves Using these Settings. Be Sure the Piston is at TDC on the Compression Stroke.**
>>If you Remove the Valve Cover and then Turn the Engine by Hand, you can Watch the Intake Valve Movement. When the Intake Valve Closes, the Piston will Just Starting the Compression/Power Stroke.
>>On Some Engines you can Us a Straightened Coat Hanger and Feel the Piston.
>>Be Careful and Don't Jam the Wire in the Cylinder. Usually the Piston will Push the Wire Out of the Spark Plug Hole with No Problems.
>>If the Valves and Valve Clearances are Correct or you have Reset them and the Engine Still will Not Start, then
>>Check the Flywheel Key.
>>When the Engine Backfired, it may have Sheared the Key.
>The Valves may have caused the Backfire, but the Backfire Sheared the Key.
>>The Following is the Instruction File I Made for Removing the Flywheel from Most Mower Engines. It is the Basics and if you have a Question, Please Ask. Any Input to Make this File Better is Appreciated. ***Disconnect the Coil Wire/s from the Spark Plug. Remove the Blower Housing (metal engine cover). Remove the Coil/s. Remove the Flywheel Nut or Starter Cup (Depends on the Model). Now Attach a Steering Wheel Puller to the Flywheel Using the Threaded Holes in the Flywheel. Tighten the Puller. Now Hit the Puller with a Hammer. Repeat this Procedure Until the Flywheel Pops Up or can be Lifted Off the Crankshaft. On Some Models you Can Not Use a Puller and and the Jaws of a Standard Puller will Not Fit. On these Type Engines you can Use a Pry Bar and a Pipe Cap that is Slightly Larger than the Crankshaft. Place the Pipe Cap Over the Crankshaft to Protect it. Place the Pry Bar Under the Thick Section of the Flywheel and Pull Up Against the Flywheel. **BE CAREFUL DO NOT PUT A HOLE IN THE BLOCK UNDER THE FLYWHEEL** Now Hit the Pipe Cap that is on the Crankshaft (covered with the Pipe Cap). Repeat the Procedure Until the Flywheel can be Lifted Off the Crankshaft. *** Be Sure you have the Flywheel Torqued to the Proper Torque (I require the Model and Spec/Type Numbers Off the Engine to Provide the Proper Torque) and Set the Coil Gap to .020in..
>>You can Locate the Correct Specification (Bolt Torque, Valve Clearances, ect) for this Engine at this Site Addy; http://outdoorpowerinfo.com/engine_specs/ and Select your Engines OEM and the Specification Chart you Require.
>>If you Hit a Snag or this Does Not Correct the Problem, I Hope to be Here if You Require More Assistance. Hope this Helps. Let me Know What Happens, Please. May the All Mighty Bless You and Yours. Be Safe and Happy. Thanks.
Good Luck
Respectfully
John
PS: I am Allowed to Answer 5 Questions a Day. If you See I am Maxxed Out, then Try Submitting your Question at or Just After 8pm EST (US). My New Day Starts then. Comments and Ratings are Greatly Appreciated. Thanks.
Respectfully
John
