- This topic has 29 replies, 13 voices, and was last updated 2 years, 3 months ago by
.
-
Using a ¼" to ⅜" brass elbow (Back in the ’40s you could find such things in the corner hardware) and using ¼" copper and ⅜" glass tubes made a site gauge I could put in place of the needle valve and check the float level without taking anything off the motor but the needle valve. An "O" ring works well on the glass in place of the brass grommet. The antique hardware here in Tampa that had such things burned down about 10 years ago – a national tragedy …
. . . 😥
I have a 4421. I think the coil is bad. Both spark plug wires come out of the one coil. Part #275370
i get no reading from either plug and any one of the coil leads. Between the two plugs there is resistance readings. This coil is hard to locate on the web. Any idea if this interchangeable with other motors?
thx
To test your coils primary windings, set your ohm meter at it lowest setting and undo the one wire from the points, shown in the circle. Hook your meter up to this wire and anywhere on the mag plate, as the plate is grounded by the other wire coming out of the coil and which is soldered to a hold down screw. This ohm reading should be very low, probably less than one ohm.
To check the hi voltage secondary windings, set your ohm meter at a higher range, usually 20K on most non auto ranging multimeters. This reading will be taken off the two terminals on the outside of the coil where the plug wires get soldered to. This reading will be much higher than the first, probably up around 7 – 9 thousand ohms. If your meter shows OL or doesn’t show anything across these terminals, the windings are open and the coil must be replaced. Since this coil is a dual firing coil (both cylinders fire at the same time), the secondary reading must be taken across these two terminals and not from one terminal to ground. The secondary windings are isolated from ground and any reading from one of the terminals to ground indicates an internal short and then the coil must be replaced.
It should be noted that both spark plugs must be installed or grounded and both hi tension leads hooked up for this system to work properly. Having one spark plug undone will open the circuit causing a no spark on the other cylinder. If the other cylinder does spark with the opposite lead undone, then the current is probably completing the circuit inside the coil. In other words, it shorting out inside the coil and destroying it.
Also check for continuity from each secondary terminal on the coil to the plug terminal. This should be a low reading to, around one ohm. Anything much higher or an OL reading indicates a broken plug wire or possibly a poor connection from the plug terminal to the plug wire.
- You must be logged in to reply to this topic.
