Well here goes my attempt at testing procedures. As no one volunteered to proof my work to see if I’m right in my way of doing things don’t assume I’m correct. If I have something wrong or I should add a test let me know. As per brichters request I tried to keep it simple.
These tests shown here are for a no spark scenario with a distributor ignition. I assume that if you know you have no spark that you do have battery voltage. These tests should work on almost any similar engines, including single cylinder. The sequence may differ slightly and some may not be needed depending on how the unit is wired.
The mock up in the photos are, I believe, the way the Cub is wired from what I see on my Cub and what's in the operators manual. It is set up as a 6 volt positive ground. As you can see I used a single spark plug instead of a distributor cap to keep the mock up small. Also you may notice that my volt readings may be a little low, that’s because I’m using a battery that is no good and with it being bad the charger doesn’t put out much voltage.
The Pos. of the meter or one side of a test light goes to the Pos. (+) post of the battery or to a good ground, for all the tests shown here. For all of these tests a volt - ohm meter or a test light will work. I have both hooked together in these photos. Make sure you always have a good connection with the meter or the test light.
Test 1; No light or voltage; Wire between starter and AMP gauge bad or poor connection.
Test 2; No light or voltage; Amp gauge bad.
Test 3; No light or voltage; Wire between gauge and regulator bad or poor connection.
Test 4; No light or voltage; Regulator bad.
Test 5; No light or voltage; Wire between regulator and switch bad or poor connection.
Test 6; No light or voltage; Ignition switch bad.
Test 7; No light or voltage; Wire between coil and Ign. switch bad or poor connection.
Test 8; No light or voltage; Coil or condenser bad. (possibly points shorted also)
Test 9; No light or low voltage; Normal condition. If you have light or normal voltage, wire between coil and distributor bad or poor connection.
Test 10; No light or voltage; Wire between coil and distributor bad or poor connection. (you should already know this from Test 9) or condenser bad. (disconnect condenser from points, if you get light or voltage then condenser is bad)
If after the tests you can’t find the problem, then the condenser or the coil is bad. I believe how to check these may be in the “HOW TO FORUM”
Also remember, each Test diagnosis is based on having passed the previous test.
I also edited Test 9 diagnosis to add low and normal voltage.
Batteries, magnetos, distributors, wiring harnesses and more.
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