Timing a John Deere B

~To set �most� late Deere "B" 2-cylinder mags so they spark at the correct time� the L/H spark plug [flywheel side] should produce a spark as the punch mark on the flywheel hub lines up with the punch mark on the bottom of the flywheel cover's center hole as the flywheel is turned in the starting direction [CCW]. [your 51 �B� should be the late �B� so use the timing dot method] ~If you aren't getting a spark at the correct time at the L/H plug wire as the punch mark on the flywheel hub lines up with the punch mark [at the bottom of the flywheel cover center hole] when the flywheel is turned in the starting direction [CCW], but the spark is within a couple of inches of where it should be, loosen the mag hold down bolts & turn the top of the mag forward to retard the spark or turn the top rearward to advance the spark...If the spark isn't even close, try swapping the plug wires from tower to tower in the mag cap & see if it gets closer� If you still can't get it to spark at the correct place even with the plug wires in the cap tower swapped, then turn the flywheel until the flywheel slot is running fore & aft [parallel with the ground], or the dot on the flywheel hub is on the bottom & lines up with the flywheel cover�s mark, then pull the mag & see if the mag drive flange slot on the governor is running the same direction [parallel with the ground], if not you will have to lift the governor [or pull the L/H governor cover] & turn the gear match up until it does. As a quick check just remember the flywheel slot & the governor�s mag drive slot should ALWAYS run the same direction no matter where the flywheel is turned.. SO, flywheel slot fore/aft = mag drive flange fore/aft.. ~The flywheel MUST be installed correctly for the above to be of any use, so �make sure� the flywheel in installed on the crankshaft correctly & the >< marks are matched between the flywheel & crankshaft. If you can't find any marks, or are in doubt about the flywheel position, remove the L/H spark plug & use a pencil or wire to feel for the L/H piston to come to the top of the stroke & at that time the flywheel [L/H impulse writing] should be at or close to the case mark. [or the dot on the flywheel hub should be at the flywheel cover�s bottom mark] ~Not all mags used on 2-cylinder Deere's fire on every flywheel revolution & not all have a solid audible snap, so make sure you are on the L/H compression stroke while setting & looking for a spark. ~If you post back with the mag brand & model we can give a little more specific information based on your mag.. ~If you are getting a spark at the correct time per the above & it still won't fire with a little gasoline in the cylinders, you either have a weak spark [is it BLUE when you see it? [If not post back], or you have bad spark plugs, [replace them, as fouled spark plugs are a leading cause of not starting in old 2-cylinder Deere's], or you have other problems like low compression, stuck valves, or ?..... .....

It helps to print this out & take it with you when you work on the tractor, also put a copy in your owners manual..

Any questions on the above just post back or E-Mail me..

I also sent you a copy by E-Mail... [email protected]

To make it right,,,,, ,, lift the governor (dont forget that oil line underneath),,,,, ,, have the LHI at 3 o clock,,,,, ,,install the governor gear so the drive slot is flat horizontal fore and aft.

MAG TIMING

You loosen its mountign bolts and time it CCW to advance or CW to retard so the mag snaps to fire just as the flywheels LHI mark passes by 3 o clock, thats when the left cylinder is at TDC. If too soon before, she tends to kick back.

If she pops n spits n backfires etc. You may have the mag in 180 out, it fits either way into that drive slot. NOTE HOWEVER if its a non gear reduction drive mag like a Wico C or X (they fire at BOTH TDC's power and exhaust) a plug wire reversal makes them run. Or, you can remove it and rotate it or the flywheel 180 and reinstall. Most originally had the top wire to left plug and bototm to right.

SUMMARY, get the governor drive slot flat horizontal fore and aft when the flywheels LHI is at 3 o clock,,,,, ,,,,time the mag so it snaps to fire the left cylinder on its TDC by rotatign it CCW to advance or CW to retard,,,,, ,,,,if 180 out, swap wires (if a non gear reduction mag) or remove mag and rotate it or flywheel 180 and reinstall,,,,, ,,,then see what happens and let us know and what mag you have.

Post back or e mail me at [email protected] or feel free to call me at 812-824-4608 and I will do my best to help you out.

Good Luck n God Bless ya Andy

John T