Is my Boyer ignition failing???

i am helping a freind troubleshoot his ignition system on a 74 850 Commando. What the bike does is just die or stutter for a second. When it dies is usually will start up after a little while. When it fails and quits running I pulled a plug and grounded it to the frame and NO SPARK. I had previously installed a used Boyer on his 850 Commando. i hard wired every connection from the switch to the boyer. i jumped the kill switch and grounded the boyer securely. The ignition switch seems fine and it does not misbehave when jiggled?? I cannot find any type of intermittant connection whatsoever so my question is are older Boyer units prone to fail in this way??? I inspected the sending unit at the points and all wires look good and all connections look good?? Any other ideas?? As I said I had carefully hard wired all connections to the boyer and It worked flawlessely for several years only to now have this intermittant failure. Thanks or any ideas--Mark Cigainero

Mark

You should be able to see voltage variations at the lead coil (the coil the black wire from the Boyer connects to--the negative terminal on the coil) as the bike is kicked over. The voltage should vary widely--say 2V DC to 10V DC as the magnets in the points cover make or break contact to fire the coils. If there's no variation in voltage, the points wiring may be grounded, the voltage to the Boyer may be too low, the Boyer stator or rotor may be bad, the system may not be grounded properly, the coil may be bad or the box may be dead. I've had Boyer boxes fail intermittently and completely, but it's worth while to check out the cheaper components first--good luck


Tim Kraakevik
kraakevik@voyager.net
Two Commandos

Another place to look for problems is the timing side of the crankcases, where the stator wires enter. It's common for the insulation to be worn off the wires there and get shorted to ground.

Other than the intermittant wires at the stator, these little beasties are amazingly reliable. I did have one fail once, but only after 25 years of flawless service.

The pickup coils have very fine wire connections that can break just inside the potting and you'll tear out lots of hair before you replace the stator.

...or it could be the black box which in my experience are susceptible to several already-mentioned failure modes, not to mention others.

Coils seem to be least likely.

Check the Boyer troubleshooting guide for tests to run.

The magnets on the spinner weaken over time. The common test is to see if the centre bolt can be suspended from one magnet. I have now got 3 retired analogue Boyers and went over to the Pazon Sure Fire.

Mick

My experience is that when they go, they go. No gradual degradation of functionality. Check battery voltage for 12.5 v plus and that the stator is charging as designed.

pvisseriii said:

My experience is that when they go, they go. No gradual degradation of functionality. Check battery voltage for 12.5 v plus and that the stator is charging as designed.

Click to expand...

I have had two Boyers fail intermittently exactly as the original post described (both with good batteries).

The replacement Sparx units are still humming along nicely on those two.

Maybe it was the Texas heat...