Boyer Bransden Induction Discharge unit on a 1974 450 MKIII

[themoudie]

Whilst rebuilding my 1974 450 MKIII engine, I made the decision to use a Boyer Bransden Induction Discharge unit on my 12v negative earth system, using an Electrex alternator, without intergrated ignition and an Electrex rectifier, points, with the mechanical auto advance unit.

I found that the red LED light that illuminates when the points open greatly assisted in the ignition timing that requires static timing to be at 0°BTDC with this engine.

I have had a challenging time trying to get the engine to run smoothly at tickover and on low throttle openings. I suspect that this has been due to carburation problems, but I wanted to clear an apparent anomaly in the fitting instructions and fitting diagram for the unit. This query was reinforced by a conversation with two auto electrical engineers and by comments from others on this forum. So I post in full my query to Boyer Bransden and their reply in full.

My query:
"I have fitted the unit to my 1974 Ducati 450MKIII and have now run the machine for approximately 200 miles.
I am unable to achieve a steady tickover and the lower rev range running is very erratic.
Whilst I believe this to be a carburation problem, it has been suggested that fitting the condenser between the points may be contributing to the problem!
If the unit removes the current from the points, so that they act merely as an electrical switch, why is the condenser still necessary?
I have read the fitting instructions thoroughly and believe that I have the unit wired as shown in Fig.5 at the bottom of page 2.
An explanation and advice would be much appreciated in my quest to have the engine running correctly.
Thank you."
and in reply
"A faulty condenser can affect the switching operation of the points.
The I.D. unit can be run without the condenser, try disconnecting it to see if the running improves.
Also check for smooth operation of the mechanical advance mechanism."

I hope that this clarifies this anomaly and assists if anybody else chooses to use a points and Induction Discharge system on their Ducati single.

BillR

[Duccout]

Let's hope that disconnecting the condenser cures the problem!