Topic: Condensor /Capacitor tolerances

[Hondell]

At the risk of offending Hondaman and getting flamed :

" might make a suggestion: since a second backing plate for the 2-3 set is not available, try setting the two so they have equal gaps, by "splitting the difference" of gap sizes between them. Then, adjust the condensor value accordingly, like this:

If the gaps come out to .016", use 0.26uF caps (Honda) or 0.24uF caps (Dyna).
If the gaps come out at .014", use 0.24uF caps (Honda) or 0.22uF caps (Dyna).
If the gaps come out at .012", use 0.22uF caps (Honda) or 0.20uF caps (Dyna)."


Can you really adjust "condenser" values to 10% or less?  In my experience finding 2 electrolytic capacitors (the kind commonly used on ignition systems) that will "match" is a daunting task (even with the Stanford Research LRC in our lab). Calculating the resonance of your ignition system is a fine pursuit but ultimately not very practical for the common SOHC owner.

[SteveD CB500F]

I don't know about ignition capacitors, but when I was a design engineer (1980s) electrolytics came as +100/-50% as standard!

[HondaMan]

At the risk of offending Hondaman and getting flamed :

" might make a suggestion: since a second backing plate for the 2-3 set is not available, try setting the two so they have equal gaps, by "splitting the difference" of gap sizes between them. Then, adjust the condensor value accordingly, like this:

If the gaps come out to .016", use 0.26uF caps (Honda) or 0.24uF caps (Dyna).
If the gaps come out at .014", use 0.24uF caps (Honda) or 0.22uF caps (Dyna).
If the gaps come out at .012", use 0.22uF caps (Honda) or 0.20uF caps (Dyna)."


Can you really adjust "condenser" values to 10% or less?  In my experience finding 2 electrolytic capacitors (the kind commonly used on ignition systems) that will "match" is a daunting task (even with the Stanford Research LRC in our lab). Calculating the resonance of your ignition system is a fine pursuit but ultimately not very practical for the common SOHC owner.

Fortunately, the Honda condensors (or whoever it is that makes them) are manufactured to the tolerance range of .22-.26uF. I first stumbled on this whole thing when working on the Suzy Water Buffalo, famous for eating points in 6 months or less. It turned out that the coils were mismatched at anything below 3000 RPM, and the arcing was pretty at night, nasty on parts. We ordered an entire box of 144 condensors and I measured them with a pulse and VOM recovery (fixed resistor, fixed pulse, time the decay to 63%, all standard electronics stuff). We found the box had mostly 0.24uF (good thing!) and lots of 0.26uf, a few 0.22uF, so I installed those 0.26uF on the 750-3 bikes when they came in for tuneups. The parts fit all the Suzy Threes, and the Honda Fours, so using them up was no problem in a year. The spark on those bikes went from a bluish green to a bright blue with the 0.26uF, and that go me started on the whole "coil tuning" bit for other bikes as well. It became one of my "great tuning secrets" in those days. I used the 0.22uF on my 750 when racing.

[bistromath]

Are those caps really electrolytic? I would have guessed they were polyester film.