Dealing With Kick-Back

I am having a lot of trouble with "Kick Back" on my A when trying to start it up. I am starting by hand, as there is no battery/charging system on the tractor now. It has been sitting in storage a couple of years. I put a rebuilt magneto on it and timed it according to the manual. I cleaned the gas tank and carb before trying to crank. It does start, but only after a LOT of pulls, and after "kicking back" two or three times. Once it warms up, it seems to run fine. I have been starting this tractor by hand since I was a kid, and this is the first time I have ever had it kick back. Can anybody tell me what the deal is and how I fix it?

Make darn sure the impulse trips AFTER top dead center. Many say to time it at tdc but that is a recipe for disaster when hand cranking. That piston crankshaft will go back wards just as well as the correct direction when the fuel ignites.

Second, often the impulse is not in good shape and will slip past the trip and therefore it will fire many degrees before top dead center. I would leave switch off, pull spark plugs and crank it many times listening for the snap and if it misses a snap I would repair the magneto.

Having cranked it for years, I am sure you know you don't spin it , just use upward pulls on crank.

The A is supposed to fire on TDC and the only way to change the timing would be to move the rotor a tooth and that will make it hard to start. If your carb is up to snuff, valves set and good compression it will start easy assuming wires and plugs and mag has good spark.

Move the ROTOR a tooth???

Timing the rotor has nothing to do with when the points open and spark happens. Rotate the top of the mag away from the block to retard the timing.

Thanks for the replies everyone. I do only use upward pulls on the crank, just as I was taught as a kid. Now I'm glad I listened! I'll try troubleshooting then retarding the mag and see where that gets me.

There is no retard just make sure the rotor is lined up with the tower where the spark plug wire goes the rotor needs to be on that spot you can make a mark on the body of the mag where the tower is then remove the cap and watch where the rotor is when it snaps if the rotor is off remove the three screws and get the rotor correct. If your carb is in shape one pull up with the crank and it will run.

When you get done retarding the spark so it doesn't kick back, please explain to Gene how you did it.

When you get done retarding the spark so it doesn't kick back, please explain to Gene how you did it.

Only way is to move the rotor and they wont start good BTDT.

If you take the cover off where the gears are that drive the rotor you can change the rotor a tooth by moving the gear. That H-4 mag is made to fire on TDC. When you have the front cover off and the dots lined up the rotor will fire on TDC like its supposed to just worked on one that went to 12v cause it wouldnt start the reason was the rotor was off a tooth.

Can't the whole magneto be rotated a few degrees around TDC?

I just watched a youtube video of installing and timing a magneto on a Cub. IIRC you start with the magneto rolled away from the engine as far as it will go with the bolts loosely installed, then rotate it toward the engine until the impulse clicks.

Time the rotor on the marks on the gears. Then loosen the 2 bolts that hold the mag to the engine & you can rotate it to fire on TDC or shortly after.

I am not familiar with the farmall cub. Maybe the magneto turns opposite of the A, B , C H & M. But the A mag turns clockwise when facing the impulse,(magneto in your hands in other words) so , you push magneto toward engine block, turn engine to just a few degrees after top dead center, never top dead or before, then pull mag toward you until it trips. like I said before, often times the wear in magneto will let it trip before it is supposed to, so that is why I said to turn it several times with switch off while checking for that early trip. It may not trip at all if worn enough. I repaired a quite a few of those mags and the tips of the weights wear, the roller they strike to hold the windupl mechanism wears as does the pivots of the weights. All of these can cause the problem he is having with kicking. That mag has a 35 degree spark lag with impulse so if the impulse does not engage you will get a spark,(although very weak) at any where from trip set to that 35 degrees before. Major kick back. Reason I said to take plugs out is so for easier observation from easy turning and you will also not be sucking gasoline into the engine. The other timing is rotor to cap and has nothing to do with when the spark occurs, just so rotor crosses the contact in dist cap at the proper time to transfer spark from rotor to cap. Also, a magneto like this is also a distributor. So many guys call battery ignition systems distributors. ?Well, with a multi cylinder engine you have to DISTRIBUTE the spark weather you have a magneto or battery ignition system, so, they each have a distributor.

I probably had that backwards. I'm working from memory and can't find the video again.

Regardless, there *IS* some fine-tunability with the timing around TDC.

You must not have any mags as the rotor does need to be lined up with the tower when it snaps if it isnt it just cant start because the spark will not be there when the engine is on TDC and you wont be able to start it the engine. Thats why there are timing marks on the cam gear and the gears on the mag that run the rotor.