Forum

[hannly]

I have a 1970 RE Interceptor that just doesn't want to fire correctly. At idle, it will drop a cylinder then come back. With a timing light on it, you can see that it is missing when it does drop a cylinder. We have put new coils, plug wires and plugs, and the timing is on. Could it be the pickup unit or the ignition box itself? It seems to be a total loss ignition as it is firing both cylinders at the same time? We can see with the timing light that one cylinder is dropping out. We may not have articulated this the best, but maybe someone has some insight. It has a Boyer Brandsen Triumph-BSA Twin MK3...an older one.

[Adrian]

Hi.



assuming the wiring and connections are OK, then it could indeed be time for a new TCI box or trigger plate.



The Boyer Mk3 tends to go full advance if the battery is giving less than full voltage and could cause back-firing. You might not have experienced THIS particular problem along with your intermittent firing issues, but it is sufficient reason to replace the Mk3 as it is.



The Pazon Sure Fire electronic ignition was developed by ex-Boyer staff looking to improve the low-voltage performance (they succeeded), and Boyer themselves came back with their own improved version, the Mk4. If you need to replace, then the upgrade (either Pazon or Boyer Mk4) is a definite plus.



A.

[Bullet Whisperer]

Hi, if your ignition is wasted spark and one cylinder is running ok but the 'other' cylinder is not, your ignition unit is probably not the culprit, seeing as how both plugs will / should spark together. Have you tried swapping the connections, coils etc to see if the trouble moves to the other cylinder? It might be a duff or oily plug. Have you got resistor plugs AND caps fitted - you don't want both, but it is surprising how many bikes seem to end up with both, causing all sorts of bother.

[Mark M]

I'll start by saying I haven't fitted electronic ignition to any of my Interceptors but my pal Ed put an electronic trigger unit (not a Boyer) on his Super Meteor and had endless problems exactly as you described. The problem with his was the trigger unit, one failed completely and two replacements went intermittent on one cylinder. I'd do as Paul (BW) suggests but given it is an older unit I'd be budgeting for a replacement. I have an original Lucas points and advance retard unit on my Series 2 and this has worked well until recently when it stuck at full advance which I discovered was the cam and it's backplate parting company with each other! A trip to my friendly welder fixed it but at least it is fixable, the number of folk who come on here with electronic ignition problems really makes me wonder! Good luck with it and let us know how it goes,

REgards, Mark