Small Engines (Lawn Mowers, etc.): Briggs&Stratten Motor, briggs and stratten, garden tiller

Question
I have a Briggs and Stratten motor on a MTD garden tiller. 3.5HP. It has no spark to the plug. I cleaned the flywheel with emery cloth and replaced the spark plug. Still no spark. Do you know what the problem would be? I was told there are contacts under the flywheel. If this is the problem, how do I remove the flywheel to clean these contacts? What would you suggest? Previously, I was getting a weak spark, but now nothing.

I also have a Homelite gas grass whip. It starts but when given more gas, it tends to die out. Cleaned the spark plug. It will run on half choke but has no power. Could this be a diaphram problem or what would you suggest? If so, how do I change it?  Thanking you in advance for your input!!

Answer
Hi Bob,

Yes, if your engine has ignition points, they would be located under the flywheel.  See my removal proceedure below.  If no points, the ignition coil may be bad.

With the trimmer, try adjusting the mixture screws.  The high speed mixture screw is initially set at 1 & 1/2 turns out, then adjust it to give good acceleration and top speed, while not closing the screw more than you need to.  The low speed mixture screw is set at 3/4 of a turn out, then adjust to give a smooth idle.  If no change, then yes, I would rebuild the carb, including a new diaphram.  Check the in-tank fuel filter, if equipped.  Also the muffler and spark screen for carbon clogging.

The flywheel is located
under the recoil/cooling shroud. Its' bore is tapered and mates with the tapered crankshaft. The keyway in the flywheel and shaft keeps it from spinning on the shaft.  A nut secures it.  Use an impact wrench on
the nut or a strap on the flywheel.  Don't put force on the cooling fins or they will break.  The recommended way to remove a flywheel is to use a puller.  An
alternative, is to tap on the crankshaft top, with a brass hammer or use a punch tip on an air
hammer.   The flywheel will need to be held up and supported or upward pressure applied with 2 large prybars. (A 2 person job.) Care is needed so the flywheel
doesn't crack or bend.  Also be careful to not mushroom over the crankshaft top.  Re-install the flywheel after cleaning the tapers and re-tighten the nut to 65 ft/lbs.

Let me know how you make out.
Michael