View Full Version : '73 Bonneville power loss

04-25-2012, 5:37 PM
I posted a few weeks ago about my '73 Bonneville that was having major electrical issues. Fast forward to now, and with help from Dan at Franz and Grubb I put in new coils (two 12v), new condensers, plugs, a new battery, and new points. I rewired everything and set the timing, and it was running perfect, better than ever, but today after ten minutes of riding without any problems it began to sputter and lose power.

I limped home and with the engine running checked the voltage. It was low and jumpy, going from 12.2 all the way down to 5.4 and hitting everything in between. I wonder if the new condensers could be fried, or maybe a problem with my tympanium?

Also, yesterday the bike wouldn't start at all. I checked the battery and it was at 12.1, so I charged it for an hour and it started up first kick. No problems until now, and I thought maybe this was because of the charging system, probably a weak rotor. Does anyone think that could be the issue causing the power loss and erratic voltage?

Torch, I've been reading all of your posts and am grateful for all the info you've passed on. If you're reading this, do you think switching to one of those Pazon units and a battery eliminator would be a way to fix this? Of course, I'd want to put in a new rotor, too. Do you guys still sell complete battery-less kits?

Thanks in advance, you guys.

04-25-2012, 7:46 PM
Yes we have the "No Battery kits" available, and Pazon ignitions are great to have as fas as a maintenence free set up but if your points and advance unit are working correctly then you don't really need a Pazon,
if you charging system is working well.. ( but it kinda sounds like it isn't ) then maybe...a new rotor might be necessary,
but I need a little more info on what you have in the bike to help you make the best decision..
1. what sort of charge unit do you have? the stock zenor diode? or a Tympanium or ?
2 . have you ever check the running voltage with a volt meter at idle? and then turn the lights on and check it at about 3k rpm you should be getting at least 12.8 volts back into a fully charged battery with all the lights on.

if you get all scrambled, just call me at the shop 714 974-1438 during the day.

04-25-2012, 10:28 PM
Torch, thanks for the reply!

The points are new, and as far as I can see they're working fine. The advance unit is pretty okay still, but it's the original one from '73 so even though it's working I wouldn't rule out replacing it. I'm leaning more and more to this being a charging system problem, but the last time I had crazy sputtering/power loss like this, new condensers sorted it out. Frankly, I just want to upgrade to an E/I and Sparx with a new coil and just be done with it.


1. I'm running a Tympanium, and
2. I'll check the running voltage at idle and 3k first thing tomorrow and get back to you.

In any event, if you guys have the "no battery" kits available, I'll probably end up swinging by your shop sometime in the next week to take one off your hands.

Thanks again.

04-26-2012, 4:58 PM
Rolled the bike out after the rain this morning and checked the running voltage. It was still all over the place, so I did what I definitely should have done first and I checked all the connections (huge DUH) and found that one of the condenser grounds had rattled loose. Tightened it up and with everything back in place the bike runs great again. Voltage with the lights on, around 3k, is a steady 12.9.

Thanks for the help, Torch. Regardless of how it's running now, I think I'm still gonna upgrade to one of your no battery kits. I'll be in the shop as soon as my nickels will allow. Thanks!

04-28-2012, 8:15 AM
yea, it's a fact on a motorcycle, the more electrical connections you have, the more chances of a problem you have.

2 sets of points, 2 condensers, 2 coils, 2 battery connections and a 40 year old advance unit .... when all that is gone, a lot of problems are gone.

05-07-2012, 8:07 PM
That new rotor you sold me the other day has the bike running incredibly well. Thanks, Torch! I'll still come back for the no battery kit.