Sparks, Get To The Point
How to Fix Your Go Kart Spark / Ignition System
If you're having an issue with weak spark, or no spark, the cheapest and easiest repair after changing the plug is to change the points. Note that not all engines use points.
If you're having performance problems with your small engine, this repair, along with gapping the coil might drastically improve the power.
Overview of System
The magnet on the flywheel and the coil are visible when the recoil starter is removed. To change the points you don't need to remove the coil, but checking the gap at this time is recommended. For most Briggs, the gap should be .006".
The points and the condenser are located under the flywheel. Points are to be gapped at .020". You can file the points and re use them, but the replacement parts are very inexpensive, so replacing them outright isn't prohibitive.
Remove the Starter Clutch
Start by removing the recoil starter housing, exposing the flywheel and starter recoil clutch.
Using a special tool, or a pair of channel lock pliers, grasp the clutch and turn counter clockwise to remove the clutch. Use a stout screw driver between two of the thickest fins to keep the flywheel from moving.
The flywheel is cast iron, which is brittle. Be careful with it.
If your starter sometimes doesn't catch, or if its sticky and it is hard for the spring to recoil it, open up the clutch with a cold chisel. There should be no lubrication of the bearings inside. If it's sticky, clean with carb cleaner to get all dirt and grease out. Don't grease the bearings; lubrication will attract dirt, which will make the clutch stickier.
Remove the Flywheel
Special pullers are made to remove the flywheel, but we found that a large 2 or 3 jaw puller worked just fine. The puller will need just a partial turn to break the flywheel loose.
The cover for the points will now be visible. Remove the screws and inspect the overall system.
There should be no moisture or oil behind the cover. If there is, new seals will need to be installed. Contaminants behind the cover speed fouling of the points.
New points kits are available at most hardware stores, and at lawn mower dealers.
Remove and inspect the contact points for burning and strange wear, then discard the condenser and the rocking arm. Install the new ones, using caution not to strip the small bolts.
Gap the points at the recommended distance using a feeling gauge.
Finally, use RTV gasket material to seal the hole where the wires exit the cover.
Reinstall the Flywheel
Put the wheel back on, and tap with a wooden mallet, 2x4, etc. Do this evenly across the entire surface so that the blow doesn't strike just one fin, or push it unevenly.
Check the coil gap again, reinstall the clutch and housing, and you're done!
If This Doesn't Solve Your Spark Problem
If this doesn't work, then your coil is bad. Take it to a dealer and have it tested to be sure.