Jerry you are doing it correctly, full advance at 26-29 degrees is about right for a twin plug on single or a twin, it really doesn't matter whether it's a BTH or any other set up. It isn't really bout the advance curve, although there are programmable ones out there. It is about where your max advance ends up, anything over 30 degrees on a twin plug set up is likely to cause pinking at best. In 2007 I set my TPV Egli twin to 37 degrees not realizing the effects of the twin plug heads that were on the bike, result was severe pre-ignition and a sheared starter gear. At this time I was using a kirby rowbottom system (which is basically a Boyer) which worked well for many years once I had realized my error and re-set to 27 degrees full advance. About 3 years ago on of the huge (harley type?) coils failed and I decided that I wanted to simplify the wiring and other aspects, so I decided to fit a BTH with twin plug set up. I have run one on my shadow since 2009 with absolutely zero issues (22k miles on the BTH so far) of course this is set at about 36 degrees as my shadow is single plug heads. So far since fitting the BTH on the TPV Egli again I have had no issues (again full advance is set at 27-28 degrees), bike starts easily, runs fine, idles fine and no pinging! I do like the ignition system being independent of the rest of the electrics so if do something silly like leave the lights on the bike will still start, other than that it runs the same as it did with the boyer. I hope this helps.Greg,
What negative effects are there to running my dual plugged Comet with the BTH at 35°?
I just got it running and have advance set at 26°.