Small Engines (Lawn Mowers, etc.): b+s Carb setup, air mixture, air screw

Question
QUESTION: Hey John, I have a B+S model 281707-0025. I need to know how to setup the carb. The engine is on a Murray riding mower I got from the family. They ran it til it died and I have replaced the connecting rod that came out in pieces. I can't get the thing to start. It sometimes pops out of the exhaust, so I'm thinking I got the timing right, and am now thinking the carb needs to be re-setup. I have taken it out and cleaned it in a parts washer and want to know how to set the screws correctly. I have a diagram so I should just need a list of what screws to turn and how many turns. lol. Thanks for your time and I will respond when we are done. lol.

ANSWER: Hello Dan:

Did you Deglaze the Cylinder when you Replaced the Connecting Rod? If Not, then that Could Cause this Problem. Even Using the Old Ring Set the Cylinder has to be Deglazed for the Rings to Reseat to the Cylinder. ****All the Carburetor Adjustments are the Same for Lawn Mower and Trimmers. There are Several Location for the Air Mixture Screws. The Idle Air Mixture Screws are Usually Located at the Top of the Carburetor Bowl and the Top of the Carburetor Body. If the Main Air and Idle Air Mixture Screws are Side by Side on the Side of the Carburetor, then the Idle Air is the Farthest from the Engine. The Main Jet Air Mixture Screw is Located in the Bottom of the Carburetor Bowl or Beside the Idle Air Screw on the Side of the Carburetor Body. Some of the Older Model Carburetors have the Main Jet Mixture Screw Straight in from the Top of the Carburetor Body (this is Rare anymore). If you have Cleaned the Carburetor (Disassembled and Soaked Overnight in Carburetor Cleaner (I Use Gunk). Then Blow Out the Passages with Compressed Air and Install a New Kit if Required. Now Setting the Air Mixture Screws:  ****Turn the Idle Air and ****Main Air Mixture Screws In Until SNUG **Do Not Jam** Then Reverse Both Screws 1 1/2 Turns. Holding the Throttle Full Open, Start the Engine. Turn the Main Air Mixture Screw Clockwise Until Proper Revs are Obtained. Occasionally you May have to Turn this Counter Clockwise to Achieve the Proper Revs. Now Allow the Engine to Idle. Set the Engine Idle Screw (Not Idle Air) so the Engine will Stay Running if Required. Now Set the Idle Air Mixture Screw so there is No Hesitation when Throttling from Idle to Full Throttle. Reset the Engine Idle if Required.**** If you Hit a Snag or this Does Not Correct the Problem,  I am Here if You Require More Assistance. Hope this Helps. Let me Know What Happens, Please. Thanks.

Good Luck

Respectfully

John

PS: I am Allowed to Answer 10 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. Thanks.

Respectfully

John

---------- FOLLOW-UP ----------

QUESTION: Ya,thanks for the response. I tried to redo the timing thinking I was 180 out, and got the same thing. So,after reading tons of questions and answers on another site,I looked further and think I found the problem. Looking closely at the woodruff key on the flywheel, it definitely seems that someone must have hit something with the blade and it sheared the key. The key is in a different place on the flywheel than it is on the shaft. Hope that all makes sense to you. So anyway, I need to remove and replace the flywheel that is now wedged in place. I have tried a puller which just ripped out the threads on the flywheel, and pb blaster/prybar/hammer combo only to break off some teeth. If I can get this thing off and get a new flywheel on in the right place I feel the thing would be good as new. What ideas do you have for this? Thanks again.
Dan

Answer
Hello Again Dan:

The Cam Times the Valves and the Flywheel Key Times the Plug Firing. Remove the Blower Housing (metal engine cover). 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 Must 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.  If you Hit a Snag or this Does Not Correct the Problem,  I am Here if You Require More Assistance. Hope this Helps. Let me Know What Happens, Please. Thanks.

Good Luck

Respectfully

John

PS: I am Allowed to Answer 10 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. Thanks.

Respectfully

John