From:Dave Hennessey
Subject:RE: RE: RE: RE: RE: RE: RE: RE: Battery & Starting Question Date:Tue Oct 1 10:59:48 2013
Response to:18831
Checking for spark - Battery-Generator models (S & ST)

The kicking test for spark is conclusive, in both the positive sense (Yes spark - definitely OK) and negative sense (No spark - definitely a problem)

The kicking test is sometimes difficult to perform especially in bright sunlight without a helper.

The following tests are IN-conclusive in the positive sense (Yes spark - MAYBE OK), but conclusive in the negative sense (No spark - definitely a problem).

1) Remove spark plug, attach plug wire to plug, lay plug on cylinder head.
2) Remove points cover.
3) If points are open, move starter lever by hand until points are closed.
4) Turn on ignition
5) Open and close points with finger.

Each time you open the points, the spark plug should fire with a nice healthy spark. It's hard to describe "healthy", but you should be able to see and hear the spark.

If the plug fires, then the battery, ignition switch, wiring, coil, spark plug, plug wire, etc. are good.


The reason this is IN-conclusive in the positive sense is that the points may be pitted/corroded and work OK at finger speed, but NOT work at running speed.

Another test is similar to above, except

3) If points are closed, move starter lever by hand until points are open.

5) Use a screwdriver to short the movable point arm to the fixed point frame. When you remove the screwdriver, the spark plug should fire with a nice healthy spark.

The reason this is IN-conclusive in the positive sense is that you've completely bypassed the points, so you have no idea if they are good or not.

I'm a firm believer in replacing the points and condenser when a machine gets hard to start. Here's some examples that might be illustrative of the old points problem:

My 1954 Ford tractor (battery-generator) was getting harder and harder to start. One day I decided to spend a few dollars and replace the points and condenser. I removed the old points, and found a stalagtite on one point and a matching deep pit on the other. The metal of the points was all discolored. Ah-ha - that's the problem!

When I opened the box, I found that the auto parts store had sold me the wrong points. Ugh. I put the old points back in so I could use the tractor until the next day, but no matter how I adjusted them, it just would not start. I picked up the correct points, and when I installed them, the tractor started right up.

Magneto machines are the same. My 1948 Farmall Cub and 1970's Gravely walk-behind both suffered from hard starting, but replacing the points and condenser in their magnetos fixed their problems.

I had one magento Hummer that had bad points, but I was too cheap to replace them. Every time I wanted to start it, I had to run a points file through them - just a couple of strokes - or the machine absolutely would not start. I'm not sure of the chemistry/physics behind this one, but that's the way it was.

The price of replacement points and condenser for these old machines is pretty high, so many of us defer replacing them. But just think - your points and condenser may be 20 or 30 or 50 or 60 years old! For about the same cost as two delicious, nutritious McDonald's meals, you can give your Hummer-series bike a badly needed tune-up with new points, condenser and spark plug. has points/condenser for both the generator-equipped Model 125(S) and Model 165(ST) and for the magneto-equipped Hummer(B), and 1960's (Super 10, Pacer, Scat, Ranger, Bobcat models. Other sources may have them as well.