moe1965 752 #1 Posted September 26, 2016 I have a wheel horse SB 421 with a 11 hp briggs that will not shut off with the key i have replaced the ignition switch. it starts up lights work etc no issue. It has a magneto not a coil. the mag has two wires that come out of it plus the spark plug wire. one of these must complete the ground to shut off the motor im thinking??? Im not the original owner so i dont know if someone flipped something around. any help would be apreciated..... Share this post Link to post Share on other sites
gwest_ca-(File Mod) 11,243 #2 Posted September 26, 2016 This wiring diagram may help. This model uses a "battery ignition" type of switch and the ignition terminal controls an isolation or kill relay that grounds the magneto ignition to turn the engine off. and Garry Share this post Link to post Share on other sites
Elkskin's mower junkyard 1,117 #3 Posted September 27, 2016 (edited) 6 hours ago, moe1965 said: I have a wheel horse SB 421 with a 11 hp briggs that will not shut off with the key i have replaced the ignition switch. it starts up lights work etc no issue. It has a magneto not a coil. the mag has two wires that come out of it plus the spark plug wire. one of these must complete the ground to shut off the motor im thinking??? Im not the original owner so i dont know if someone flipped something around. any help would be apreciated..... before looking at post above i will tell you something. i work on alot of briggs what you are discribing sounds like a points magneto lol.theres number i am interested on shroud of engine somewhere should be 3 sets of numbers model type and code. the code is what we are after. first 2 digits is year engine was made. for example my 1971 sears has a engine code date of 70092301. which means engine was made in september 23rd of 1970. reason i am pointing it out is somewhere in 1982 briggs went to the magnitron setup aka electronic ignition eliminating points. the mag creates its own spark usually these mags only have a tab out backside of mag to hook kill wire too. something else never use a switch that sends power to your mag it will be toast. Edited September 27, 2016 by craftsmanmowerfreak Share this post Link to post Share on other sites
moe1965 752 #4 Posted September 27, 2016 Thanks for info someone has messed with this engine before. I got a box of parts and there were a set of points and also a I'm guessing a set of electronic ignition. That's what's in it now. I'm going to take the fly wheel off this weekend and confirm Share this post Link to post Share on other sites
moe1965 752 #5 Posted September 27, 2016 I will take pix of all the goodies I have left over and the set up that is currently on the tractor. I think there might be a mix up Share this post Link to post Share on other sites
Elkskin's mower junkyard 1,117 #6 Posted September 28, 2016 well if you have a nova box hooked or or equivlant box all you need to do is join in a kill wire from ignition switch (m post on switch) to the junction where the nova wire hooks to mag wire. http://www.ebay.com/itm/Electronic-Transistorized-Ignition-Module-Used-in-4-2-Cycle-Gasoline-Engines/231992338942?_trksid=p2141725.c100338.m3726&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D20150313114020%26meid%3De89f9b860d404f43bd64ded8583a65be%26pid%3D100338%26rk%3D3%26rkt%3D12%26sd%3D360714365046 this here is a nova box. i dont run them. to be honest its easier just getting a newer mag that dont require points lol. Share this post Link to post Share on other sites
moe1965 752 #7 Posted October 2, 2016 (edited) Here is the latest I think this might be my issue. The coil on the bottom of the picture is the one I had on the engine. The one on the top was in my box of extra stuff I got when I bought the tractor. If the one on the top is the correct one where does the extra wire go. Ground? Or to the ground on the back of the switch? Or neither. There are no points and condenser under the flywheel Edited October 2, 2016 by moe1965 Share this post Link to post Share on other sites
Elkskin's mower junkyard 1,117 #8 Posted October 2, 2016 3 hours ago, moe1965 said: Here is the latest I think this might be my issue. The coil on the bottom of the picture is the one I had on the engine. The one on the top was in my box of extra stuff I got when I bought the tractor. If the one on the top is the correct one where does the extra wire go. Ground? Or to the ground on the back of the switch? Or neither. There are no points and condenser under the flywheel ok i see. some early model magnatron did have a ground wire for one of the bolts the connect mag to block. now extra is kill wire (long) on this one looking at pic both are electronic mags aka magnatron mags Share this post Link to post Share on other sites
oldredrider 2,553 #9 Posted October 2, 2016 The replacement engine (which I think you have) has an on/off switch mounted on the flywheel shroud. It grounds out the ignition via the long wire shown in your picture. If you don't have the shroud switch, you can rig up a simple on/off grounded toggle switch to accomplish killing the engine. This is a cheaper route to take than replacing the ignition switch. Share this post Link to post Share on other sites
moe1965 752 #10 Posted October 2, 2016 Thanks. No more getting shocked while pulling off the spark plug wire. Share this post Link to post Share on other sites
