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John, what type of magneto is it??? I ask cuz some kind like the Wico C or XH Models and others that are direct driven (non gear reduction) can be installed either correct or 180 out where their male drive cog fits into the governor shafts female slot, and if they are 180 out of time or the plug wires in the wrong (top or bottom) terminals (spit n pop and backfire), a simple wire reversal will make them run IFFFFF all else is in correct time. Of if they spit n pop n backfire (out of time symptom) you could remove the mag and rotate the flywheel 180 and re install it leavign the wires in the terminals they were in. They came originally from the factory (Wico mags) top terminal to left cylinder and bottom to right. However, if they are gear reduction drive mags, they have to be instaled correct (not 180 out) and the wires in the correct terminal, or they will not run nor will a wire swap make them run. (See below) 1) You asked how to install, thats easy, just rotate the flywheel and/or the mag so its male drive cog is lined up with the female slot in the governor shaft end and install, but leave the top n bottom bolts loose so you can fine tune the initial start timing by rotating/adjustign the mag CCW to advance the start spark or CW to retard the start spark. (See below)
***********HOW TO TIME IF A WICO C OR XH********
To save a ton of time, I cut n pasted an answer to a similar question a few days back on first a short easy way to install if its a Wico C or XH which yields a 50/50 chance of being right (IF all else is in time) and then a long detailed answer on how to get it right the first time WHICH ALSO WORKS BASICALLY EVEN IF ITS A GEAR REDUCTION MAG. Im going to have to assume for now its a Wico C or XH and tell you how to time it as original, where the top tower fires the left plug and the bottom the right in my second detailed answer, while the first answer has a 50/50 chance and if wrong all you have to do is reverse the wires or remove the mag and rotate the flywheel 180 and stick her back in.
NOTE HOWEVER: There are 2 separate timing issues and you didnt specify what you needed. Theres the initial static start timing and then the lag angle setting which determines the advance she runs at over 250 RPM when the wind and trip drops out and shes running at straight crank RPM.
(I) *******SHORT ANSWER FOR START TIMING ONLY*******
******50/50 CHANCE OF RIGHT OR WRONG*********** (A) If its a Wico C or XH and your only worried about initial start timing for now AND ASSUMING THE FLYWHEEL AND CRANK AND CAM AND GOVERNOR GEARS ARE ALL IN CORRECT TIME: 1) Simply rotate the flywheel to a position where you can insert the mag so its male drive cog mates into the governor shafts female slot. 2) Leave the mags mount bolts loose and then start time it by rotating it CCW to advance or CW to retard SUCH THAT it snaps to fire JUST AS the Left Hand Impulse timing mark on the flywheel passes by the 3 o clock position flat mark on the tractors side WHICH IS THE SAME AS THE LEFT PISTON CROSSING TDC IF YOU HAVE A DIFFERNT TDC MARK. Just rotate the flywheel CCW and listen for the mag to snap and rotate time it per above so she snaps just as the Left Hand Impulse timing flywheel mark passes the mark at 3 o clock. Some set it by first rotating the mag as far CW retarted as possible, then slowlyyyyy rotate the flywheel to the LHI at 3 o clock and piston at TDC and STOP, and then slowlyyyyy yy rotate the mag CCW advance JUST TILL SHE SNAPS, then lock her down. Either way will work, I have done both but like the flywheel method where I can actually observe its mark and I can hear the mag snap. 3) NOWWWWW if the rest is all in time you have a 50/50 chance its as original (left top and bottom right) HOWEVER, if you try to start her and she pops n bangs and backfires, you can EITHER
swap the top n bototm wires ORRRRR RRRRR RR remove the mag and rotate the flywheel 180 and put her back in to make her run. Again, original was top left bottom right. Thats the short sweet fast simple way to set it ASSUMING THE OTHER GEARS ARE RIGHT and if you get it incorrect, you can merely remove it and rotate the flywheel 180 and stick her back OR swap top n bottom wires. (II) **************DETAILED ANSWER TO GET IT CORRECT ORIGINAL THE FIRST TRY************************** The long answer is if you want it as original where the top plug wire terminal fires the left cylinder and the bottom the right (to eliminate the 50/50 chance). NOTE: If its a gear reduction mag, it has to be right where the top terminal fires the left cylinder on its compression power stroke TDC and then the bottom fires the right on its power TDC 180 degrees of crankshaft (90 of mag) rotation later. On those, substitute and think below that for the left cylinder to fire on its TDC compression power stroke, the rotor has to pass by the top tower and then the right tower 180 crank or 90 degrees of mag rotation later.
1) When the left cylinder is at TDC on its Compression Power Stroke (you can remove the plug and see/feel when shes suckin in there {piston coming down on intake} or blowing out under pressure {piston coming up on compression}, thats where the Left Hand Impulse mark on the flywheel is in the 3 O Clock position lined up with the flat mark. NOTE, the mark is also there at TDC on Exhaust, but set it on Compression Power for that below.
2) At that point (once your in and timed) is where the mag should just be snapping over to fire the left cylinder, and the female drive cog slot in the governor shaft end should be flat horiziontal fore and aft. IF FLYWHEEL AND CAM AND CRANK AND GOVERNOR ARE ALLLLL IN TIME 3) The mag (before inserting into governor) should first be rotated/adjusted (you can turn its rear coupler) so its rotors first leading tip is located just before and to the top and left of where the caps top tower would be located and ready to wind and trip the spring and snap past the top terminal. Thats the FIRST LEADIGN ROTOR TIP Im talking about, it has 2. In the postion needed, I want the 2 tips like at 1 o clock (leading tip) and second lagging tip is like 10 0 clock. JUST A GUIDE NOT PERFECT ACCURATE. 4) NEXT, to insert the mag in the governor (its male fits into governors female slot) FIRST rotate the flywheel backwards maybe 1/4 turn or so but just enough to where the slots match up and you can insert the mag. If set this way, the top plug will fire at the left cylinders TDC on power compression stroke and the bottom at the right cylinders TDC 180 later. Like I said, the worse you can do is get it 180 out, in which case you have to reverse the top and bottom plug wires or remove and rotate 180 and replace. 5) Leave the mags mount bolts loose and then start time it by rotating it CCW to advance or CW to retard SUCH THAT it snaps to fire JUST AS the Left Hand Impulse timing mark on the flywheel passes by the 3 o clock position flat mark on the tractors side WHICH IS THE SAME AS THE LEFT PISTON CROSSING TDC IF YOU HAVE A DIFFERNT TDC MARK. Just rotate the flywheel CCW and listen for the mag to snap and rotate time it per above so she snaps just as the left piston passes TDC where the Left Hand Impulse timing flywheel mark passes 3 o clock. Some set it by first rotating the mag as far CW retarted as possible, then slowlyyyyy rotate the flywheel to the LHI at 3 o clock and piston at TDC and STOP, and then slowlyyyyy yy rotate the mag CCW advance JUST TILL SHE SNAPS, then lock her down. Either way will work, I have done both but like the flywheel method where I can actually observe its mark and I can hear the mag snap with the mark on side of tractor. 6) Even if the flywheel is covered and you dont need to fool with its marks, with the left plug removed, you can tell when that piston is coming up under compression (blowing pressure out the plug hole) and the governor female mag drive cog slot is coming just before flat horizontal, and rotate the mag to get it in the slot with its rotors first leading tip just before (top and left of) the caps top plug terminal, you will be right. The run time advance or lag angle is set at the mags rear coupler by loosening the screws and adjusting the index marks to the left of top center for how much advance you desire.
Good Luck, post back your findings and any questions or e mail me at [email protected]. I hope ths answers your question of how to time if its a Wico Mag PLUS gave you some theory of whats going on. If its NOT a Wico C or XH, post back.
Good luck and God Bless ya John
John T
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