Motorcycle Repair: 1969 honda dream 305

Question
was working on lights on the bike forgot and left key on & charger hooked to battery came back to find coil melted. i have changed points condencer coil plug wires energy is building up in coil but not releasing out to spark plugs.can you please help me. thanks.

Answer
Darcy, first check the coil's primary winding impedance with an ohm meter. You should see readings of about 4.5 ohms on the two small wires. If the readings are in the 2-3 range or above 5 then the coil is not appropriate for this bike.

If you have full battery power into and out of the coil windings, then the "trigger" or switch to turn the coil on and off is the point set.

Turn the engine over until you see the points open as wide as possible. Measure that gap. It needs to be between .012" and .016" wide. Adjust as necessary with the adjustment screws. Once the gap is established, turn the backing plate until the points just OPEN at the F mark alignment on the rotor and stator marks. Use a simple 12v test light to check when the points open and close. If the light doesn't go out, then the points are not closing, usually due to some preservative coating on the point faces. Clean the point contact faces and check again. I usually ground the pointed end of the test light in the point cover screw hole and then use the wire clip on the point spring or on the end of the little terminal hardware nut.

If the test light doesn't come on, then the points are grounded due to improper lead wire connection, generally. That little terminal end on the point wire must be connected to the outside of the point set spring. Sometimes, the terminal end gets twisted and grounds out on the contact base. The points are just an adjustable switch for the ignition coil to charge up and then dump the magnetic field energy, but they must be able to close, then open to energize the circuit.

Dreams used two different types of point contacts... Nippon Denso and Hitachi. The points do not interchange, by design. The other unfortunate factor is that most of Daiichi-brand aftermarket replacement points are not accurately made, so they are nearly unusable with the N-D point plates. If you bought new points for a N-D point plate, be sure to use OEM Honda (N-D) parts and not the replacement parts on the aftermarket.

Bill Silver
vintagehonda.com