Have 16hp vtwin brigs no fire checked flywheel magnet & replaced

Check continuity through the ignition switch, and make sure it isn't shunting to ground.

It is probably the timing. As the engine turns the ignition fires due to the rotating magnet passing by the "magnito" coil. If the system is misaligned or dirty it is firing the spark to soon or to late in the cycle. Pull the top and have a look could be loose or have a broken wire or need to adjust the pick up gap. I am guessing that the flywheel you replaced was involved with the pull cord which means that you had that opened that portion of the motor which exposes the magnito.

gap needs to be 10 thousands of a inch done with a brass feeler gauge ..mag/flywheel has a spot with a magnetic field if you look you can see it it should make a 1/2 wrench stick to it if not replace mag/flywheel ..check key way also

A mag or magneto is a coil of wire that is "excited" by a permanent magnet thereby inducing a high voltage to fire the spark plug with. Most single cylinder lawnmowers use mag and point systems to fire the plug. Coil is hard mounted and the permanent magnet is part of the flywheel with the points mounted under the flywheel.

A coil is a two coils of wire, one is connected to ground on one end and the other end is connected to either a set of points or an electronic switch, either of which turns on and off the current through that coil. When the coil discharges its electrical potential, its magnetic field collapses, inducing a high voltage in the other coil which is used to fire the spark plug.

Lots of possibles here. I would start by removing the spark plug and checking compression. Then remove the main housing cover and by hand, slowly turn the flywheel until the magnets line up with the mag arms (coil) and check to see if your piston is all the way up in the cylinder, if not most likely your shear key (aligns flywheel to crank) is broke. Just a thought

did you make sure the new spark plug was igniting if it is or if its weak you might have broke the flywheel key was it running fine when last used there can be alot of things it could be 2 cycle engines must have 120psi of compression ,the right fuel mixture,good plug right gap between flywheel & magnito (spark plug wire connect to to get spark) and not rust on flywheel & magnito hope this helps let me know thanks

could be a low oil safety switch on the briggs & stratton gone bad. Try disconnecting it and fire it up.

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All wires on a small engine except for the spark plug wire are to ground out the spark and stop the engine. Except a few for accessories and on generator/welders.

Knowing that, there is a small main wire that comes from your coil and leads to all other wires. It usually sits under your gas tank and runs toward your on/off switch or ignition switch. To see if it is any off your shutdowns gone bad, disconnect this wire. If still no spark then you either have a open in this wire or your magnito (coil) is bad.

If it starts, then unplug all the wires going to the kill wire and hook them up one by one until you find the one that kills the engine. Follow the wire to it's source looking for breaks in the line. If no breaks then the switch is out of place or bad.

Note: check your oil level first. Most engines come with a low oil sensor that will kill the spark if the oil level gets too low.

To check is your magnito is bad or you have a short, disconnect the wire at the magnito found by the flywheel under the flywheel cover. Tuck this wire out of the way and try to start your unit. No spark then you have a bad magnito.

First how are you checking spark. Spark tester or spark plug against metal? With a spark tester your only testing spark to the spark plug. With the spark plug against metal you do not know is spark is getting to the plug. So it's best to do both and save you time and effort. A spark plug cost less then $3 so I usually replace them when I have a starting problem automatically.

The engine may have a low oil shutdown switch. Check the oil level. If this does not do it, there should be a single black wire coming form either underneith the fuel tank or out of the casing by the recoil that leads to other wires. This should be your grounding wire for the magnito. Disconnect this wire and try to start the unit. If it starts then one of your shutdowns or switches is bad. Reconnect it while it's running to shut it down or push it's connector against the engine block to ground it out. Now if it ran you need to disconnect all wires that connect to this wire and hook them up one by one until you find one that shuts down the engine. When you find it follow it to it's source and that is you problem. If you don't get anything the next step is to remove engine shroud by the recoil (some engines require you to remove the recoil to do this). Now you should be looking a the flywheel and magnito (coil). Did connect the small wire on the magnito and tuck it out of the way so it does not get caught in the flywheel when running. Reinstall everything and try starting again. If still nothing you need to change your magnito. To set the gap on your new magnito a piece of a cigerette box or equivalant between the flywheel's magnetic portion and the magnito should give you the proper gap.


Note: all wires on a small engine are to ground out the spark except a few others on generator which provide power to generator field.

While attending college, I worked at a tool rental center and learned many tips and tricks from the mechanics. The problem that we heard the most from customers was that the machine would not start. Your your machine at least starts and runs fine, however will not shut down with the factory kill switch. Many times when replacing the mag. (spark coil) the kill wire would rub against the flywheel and break or over time the conductor wire will break inside the insulation. If you kill switch only has one wire, then all the kill switch does is short the mag to ground. Simple test is to remove spark plug, re-connect wire to plug, touch plug to engine and pull rope to observe spark, then short the tab on the magnito to ground, should be no spark. If you still have spark, coil is defective however good enough to run engine. Kill with choke or pull wire. If no spark with test, make new wire from tab of coil to kill switch or any switch that will short tab to ground. Good Luck