Weak spark from Boyers Bransden electronic ignition
Posted: Sat May 09, 2020 10:35 am
1973 GT750. I replaced my points with a Boyers Bransden electronica ignition several years ago and I’ve struggled every since to get with consistent spark. After I chased my tail with timing and carburetion I realized I was a weak spark because it was running poorly at idle and high rpm when the bike was hot but operated just fine when it was cold. It would also stall out at idle when hot by switching on the headlight. I swapped out the coils for another set of used coils it made no difference. I hotwired the coils directly with a toggle switch to give them a little more juice and did help, but still lost power the longer I drove. Fast forward and I have completely rewired the bike with new wire looms I purchased on eBay, and replaced the coils with aftermarket (admittedly I went cheap on these but the specs were as good or better than OEM). The bike starts first kick and performs beautifully for the first 20 to 30 minutes of riding BUT if I get stuck in traffic in the South Texas heat (I live in San Antonio) or ride at high rpm for an extended length of time my old ghosts come back. It loses power and is a bear to keep alive at stops. Not overheating, and it coughs like there’s I burned fuel heading out the pipes.
Here’s my theory: the Boyers Bransden electronic ignition fires all three spark plugs together, basically resulting in three times the firing rate they were made for. I spent much of the last few years eliminating loss of voltage from old wires but at this point I think the coils themselves are fatiguing due to to the firing rate. Has anyone else seen this? Does anyone make an aftermarket electronic ignition that doesn’t fire all three plugs together? What about race ignition, possibly better quality components will illuminate the fatigue? Any other tests I could run to help solve the problem? I think I’ll order cooler plugs to see if that makes a difference. New battery, new adjustable voltage regulator set slightly “hot” at 14.5V.
Here’s my theory: the Boyers Bransden electronic ignition fires all three spark plugs together, basically resulting in three times the firing rate they were made for. I spent much of the last few years eliminating loss of voltage from old wires but at this point I think the coils themselves are fatiguing due to to the firing rate. Has anyone else seen this? Does anyone make an aftermarket electronic ignition that doesn’t fire all three plugs together? What about race ignition, possibly better quality components will illuminate the fatigue? Any other tests I could run to help solve the problem? I think I’ll order cooler plugs to see if that makes a difference. New battery, new adjustable voltage regulator set slightly “hot” at 14.5V.