Question about Honda Motorcycles
I have a 1974 honda 100 XL I did a new coil and new points but no spark do I need to trim the cord or set the points if so how do I set points @
Hi, Adam and the usual suspects are:
1. Fouled spark plugs.
2. Severely discharged or a damaged battery should have 12.5 volts or more and be able to pass a proper "LOAD" test if necessary, you may have a preliminary reading of 12.5 volts or more but little or zero amperage the battery is faulty and must be replaced, AGM batteries fail in this scenario more so than lead-acid batteries.
3. Check battery terminals for damage or corrosion, check the battery cables at "BOTH" ends for loose, corroded, or broken connectors, "INSIDE" and outside the cable harness, perform connector wiggle test and check cables with an ohmmeter if necessary.
4. Loose connection at ignition coil or plug between ignition sensor and module.
5. Spark plug cables in bad condition, shorting/leaking, spark plug cable connections loose check for spark leakage in the dark.
6. Faulty ignition coil or electronic control module.
7. Faulty pulse coil.
8. Faulty CKP, CMP, or BAS sensor.
9. Faulty ignition switch.
10. Faulty run/off switch
11. Tilt sensor needs a reset.
12. Security alarm failing to disarm needs reset
For more information about your issue and valuable "FREE" downloads that you will need for viewing or printing please click on the blue links below. Good luck and have a wonderful day.
1974 honda xl100 no spark
How to Check for Spark
Posted on Jan 07, 2018
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Posted on Jan 02, 2017
1979 Sportsters were electronic no points unless they were changed during the life of the bike.
If it is points they are located on the right side of the motor under the little round plate.Points set @ .018 with the piston a TDC.Either use a screw driver in the plug hole or take the timing plug out and set the flywheel mark ( the line or the dot)inthe center of the hole.Set points.If you cant find the marks or the hole take it to a shop
Posted on Dec 27, 2008
SOURCE: wiring harness 1974 sportster???
I am assuming your bike is stock, or close to it. In 1974, all h-d's used a battery coil ignition with wasted spark. Battery positive flows from the ignition switch to the coil, through the coil primary winding to the points, then open or shorted to negative (through the chassis) depending on the points being open or closed. When the engine is turning over, this is what happens: The small cam that operates the points has the points in the closed position, so battery current is flowing through the coil primary, through the closed points to negative. This causes the primary winding inside the coil to set up a magnetic field. When the cam starts to open the points, the current tries to bridge the gap. If we let this happen, the big arc between the point surfaces would burn up in a hurry, and the plugs would not fire for the following reason: The ignition coil is a transformer. It has a primary and secondary winding.The secondary winding has many more turns of wire than the primary. When the secondary winding "cuts" magnetic lines of force a larger voltage is induced in the secondary. In the case on your sporty, we are boosting 12 volts to over 10,000 volts. This depends on 2 things: The number of lines of force and the speed they are cut. So, when the points just start to open, the condenser absorbes the current until the points are open enough to prevent arcing. Then the current flow through the primary winding stops. The magnetic field quickly collapses, cutting through the secondary windings that are connected to the spark plugs. The resulting high voltage (pressure) Jumps the gap on both plugs and lights the fire. One of the cylinders is on the exhaust stroke so that spark is wasted. So: ignition on : 12v at coil positive. With points closed, 0 volts at coil negative. If you read voltage here, the points are dirty or open or the wire from the coil to the points is open. Points open: 12 volts at coil negative. To check for spark, you don't have to crank the engine. Just manually opening the points should fire the plugs. After you get the plugs firing, post again and I will tell you how to razor tune this thing. It should start instantly with a perfect idle. Hope this is clear.
Posted on Jan 01, 2009
SOURCE: no spark
alrighty, I had the same issue with my bike. It took days of tracing the issue with a volt meter and I discovered an intermittent short that would "fry" my coi. This made the bike not start and when I replaced the coil, because I had removed the old coil and moved the wires the issue disappeared for a short time. It is known that SOMETIMES when the coil is mounted the two wiresthat go to the coil somhow get stretched. This over time cause an intermittent short and the coil is rendered "dead". The Fix: 1.get a replacement coil. 2.you need 6 inches of #18 wire 3. two aluminum wire splicers and two aluminum circle fittings for the coil posts. 4.take off the old coil. 5.cut back the wires that go to the coil about an inch. 6. using the aluminum splicers splice the wires making them about 3 inches longer. 7.splice in the aluminum circle fittings. 8.mount the new coil. 9. fire the bike up. Enjoy riding.
Posted on Jun 06, 2009
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