Jump to content

Unofficial Home of Old Simplicity & Allis-Chalmers Garden Tractors

Sign in to follow this  
NLM

Another Briggs with no spark

Recommended Posts

NLM
I need some help with my briggs 243431. I put in a new coil, points, condensor, and plug. I get a faint spark from the plug wire to the head bolt, but can't get anything out of the plug. I didn't remove or change the flywheel in any way. I did, however, slightly change the ignition wire from the coil to the points. They were screwed together to a small tab that looked like it broke off from somewhere. I stripped the leads and connected them together and taped them. What next?

Share this post


Link to post
Share on other sites
BLT
Ok the start of twenty questions, what about the gap between the flywheel and coil legs. Is that about .010-.012. Being that you are getting a spark rules out any sort of grounding. Those two pieces you taped togeter probably was mounted on a piece of bakelite where you would connect grounding wire to ign switch. BLT BT

Share this post


Link to post
Share on other sites
HubbardRA
NLM, If you don't have a non-metallic feeler gauge to check the flywheel/coil gap, I have used matchbook covers before with good success. I can't help much with the magneto, I have switched my 243431 over to battery ignition by using a Kohler coil with the B/S points and condenser. Been running this way for 15 years and haven't replaced the points or condenser. Put the Kohler coil on 3 years ago because the motorcycle coil I was using before that died.

Share this post


Link to post
Share on other sites
PatRarick
You said that you did not remove the flywheel. What were the circumstances requiring you to replace everything in the ignition system? If it was weak or no spark, the problem could be a partially sheared flywheel key. Since everything else is new, and if you are sure as to the point gap and the amature (coil) air gap, this would be my first check. From there, make sure that you have a good ground connection between the armature and block, and the points/condenser and the block. Faulty new parts or a weak flywheel magnet are remote possibilities. If the new armature was OEM, there should have been an instruction sheet included that doubles as a gauge to set the armature air gap. If not, I use three thicknesses of note paper. Loosen the armature and pull it away from the flywheel and tighten the screws. Turn the flywheel so the magnet is directly in line with the armature. Lay the paper over the magnet, then loosen the armature screws allowing the magnet to pull the armature tight, sandwiching the paper between the flywheel and the armature. Tighten the screws, then turn the flywheel to remove the paper. Pat

Share this post


Link to post
Share on other sites
PatRarick
I should expand on the flywheel key possiblity. Before Briggs had electronic ignition, the flywheel key was made of a material that could only partially shear. To generate spark, the flywheel magnet has to pass the armature as the points open. depending on how far the key shears, it is possible to maintain spark, but it will be weak. Magnetron will create spark each time the magnet passes the coil, regardless of whether or not the key is sheared. A partially sheared key will throw the engine out of time far enough so that the normal spark could cause a dangerous backfire or kickback situation, where the weak or no spark condition of the point system would not allow this. For this reason, the composition of the flywheel key was changed so that the key is supposed to shear completely. The theory is that this will throw the timing so far off, that backfiring and kickback will not be a problem. Notice that I said "THEORY". In short, an original, old style, or aftermarket key may only partially shear, creating a week spark in a point type system. Pat

Share this post


Link to post
Share on other sites
Guest
This topic is now closed to further replies.
Sign in to follow this  

×