Harder starting JD H

I have a question on my 1940 John Deere H handstart tractor. I just had to have the magneto rebuilt because it wouldn't start. Ever since then the tractor is much harder to start, anywhere from 4 to 6 rotations of the flywheel. Prior to rebuilding the magneto, it would start with one rotation, every time. What would cause this? New plug wires, points and condenser as well.

Thank you!

Does it have good spark now? Timing OK? What kind of wires? Need copper wire core. Ron Mn

If the only thing that has changed since it started easy to now was the magneto being rebuilt, I would say that timing would be the first thing I would check and confirm. I know that my B was very hard starting coming out of a restoration, it was due to the fact the timing was too retarded.

The spark is great. How do I check the timing though?

I haven't had one apart in a long time but possibly the impulse coupling was assembled wrong. To retime it, loosen the mag bolts and roll the top back all the way. Roll the flywheel through compression on both cylinders then till #1 is coming up on compression. Turn it slowly till the L H Impluse dot lines up with the timing mark and stop. Then roll the mag forward slowly till the impulse trips and clamp it there. If you have the wires disconnected at the mag, watch where your hands are when you turn the mag or you'll get a surprise.

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Agree with all others that it is a timing issue.

You might consider checking the timing on the No. 1 (flywheel side) cylinder.

To prevent the tractor from accidentally starting:

Remove the spark plug cable from the No. 2 spark plug.



Make sure the gas is turned off.

Lock both brakes.

Transmission should be in neutral and the hand clutch should be disengaged.

This is one method of checking the timing.

Remove the No. 1 spark plug on the flywheel side.



Place your finger over the hole and rotate the flywheel in the running direction (counter-clockwise) until you feel pressure (compression) of air in the cylinder.

Continue rotating the flywheel counter-clockwise slowly until the ?[b:654c4848f0][i:654c4848f0]L. H. IMPULSE[/i:654c4848f0][/b:654c4848f0]? mark on the flywheel lines up with the reference mark on the gear cover.



Loosen the two cap screws securing the magneto.

Tap the top of the magneto toward the rear of the tractor a little at a time until the impulse trips.



Tighten the cap screws and continue rotating the flywheel counter-clockwise until you see a spark at full pressure (compression) for No. 1 cylinder.



Hope this helps.

Mea culpa. John got it right. Top of mag forward first, then back till it trips. It's been a while.

I leave the plugs in & check timing by looking at the timing marks & rolling flywheel. When #2 exhaust opens, #1 is near TDC with both valves open between exhaust & intake so there is no compression in the engine. Watch the marks & listen for impulse trip. With #1 in transition (both valves open) and #2 in exhaust it's easy to roll 'em back & forth. Roll it backwards until you feel compression to re-set the impulse dog then go forward watching the timing marks and listening for the impulse trip. I find it much more accurate than the "rocking the mag" process!

Just get it close by the method listed in the book and bolt the mag down then rock the flywheel watching the marks & listening for the impulse trip. If it trips early, loosen the mag & move the top forward a bit then try it again! I set 'em between zero and a nickel's thickness AFTER but never before!

Years ago we had a bar with one of the steering wheel cranking pins welded to it & regularly used that to crank start a long hood A. Once you've been kicked by an A who's mag tripped early you'll make absolutely certain to NEVER again have a mag trip BTDC! At 0? or after is OK but never BTDC!