Subject: Re: parts needed
Author: Patrick Hayes
Date: Mar 6, 2005, 11:18 AM
Post ID: 1718499077
andy hill wrote:
| is there any way to test an ignition coil? the other bike still has no fire. 12volts in, 12 volts out, no spark. tried a new napa coil, nada. |
Trial and error unless you have a coil bench tester. Rare items. Since
you have used a new coil with the same results, I'd start looking elsewhere.
The coil gets "energized" when the points are closed and contacted.
When the points open, the 12v circuit to the coil is broken. The
energized magnetic field within the coil collapses catastrophically and
"induces" a huge whack of high voltage spark in the process.
The breaking of the 12v coil circuit happens by opening the points.
However, this is a dynamically slow, gradual process as the points are
levered open by the rotating cam and there is some voltage bleedoff at
the contact surfaces as they open.
So, we use a condenser as a small, temporary electrical storage device.
It is there to keep a good voltage supply in the 12v circuit until the
point contact surfaces are fully separated. Then the condenser finishes
its discharge INTSTANTLY and this leads to the catastrophic field
collapse and subsequent spark generation.
What's the condition of your point contact surfaces? Are you sure there
isn't any debris causing a short of the 12v circuit? Have you
substituted a replacement condenser?
Patrick Hayes
Fremont CA