heat related electrical failure ?

[whynot2]

After trying Iridium plugs in my '81 H I went back to stock plugs and discovered a charging problem. I tested rotor, stator, rectifier, and coils by the books, Yamaha, Clymer, Haynes and Chilton. My rotor was out of spec, everything else was okay. I bought and installed a rebuilt rotor from Ricks. Charging 14.4 volts at 3000 rpm, I'm happy, almost. I can ride as long as I want, but if I stop and the bike sits in the sun too long and gets hot, it run like crap, missing, won't idle and tries to die. Yet I believe it is still charging the battery, it is higher when I finally get home then when I left. I have yet to have it happen when I have my meter with me.
Any Ideas?
Whynot2

 

[retiredgentleman]

After trying Iridium plugs in my '81 H I went back to stock plugs and discovered a charging problem. I tested rotor, stator, rectifier, and coils by the books, Yamaha, Clymer, Haynes and Chilton. My rotor was out of spec, everything else was okay. I bought and installed a rebuilt rotor from Ricks. Charging 14.4 volts at 3000 rpm, I'm happy, almost. I can ride as long as I want, but if I stop and the bike sits in the sun too long and gets hot, it run like crap, missing, won't idle and tries to die. Yet I believe it is still charging the battery, it is higher when I finally get home then when I left. I have yet to have it happen when I have my meter with me.
Any Ideas?
Whynot2

Could be ignition coil failing with the heat, or could also be the TCI failing.

Can I assume you have already replaced the stock fuse panel with more reliable fuse holders?

 

[rebel542]

Doesn't figure. A running engine gets a lot hotter than one just sitting in the sun. I'm assuming that it doesn't happen all the time from your comment about not having your meter with you when it occurs. Think about it hard. It's probably telling you whats wrong, you just got to listen. Any more info? Anything different happening when it craps out. Does anything you do make it better or worse.

 

[jd750ace]

A good charging system trying to supply an ould tired circuit is soon over-worked. Fuse holders is a good start, and if you have the original coils, they are probably going south as well.
Better help comes with more details about your bike.

 

[whynot2]

MY H still has the original fuse holder in it. Since the bike sat half its life without a battery installed, and I remove it for 6 months out of the year, and the fuse holders themselves still have spring to them and grip well, I think they are okay for now... The coils are original, 32 years old this October and stuck up under the tank where once the bike is stopped, they don't get to cool much. To compound the problem I positioned my Fiamm horn up in the triangle which further blocked the cooling flow to the coils. (Since removed.) I have a set from my 1980 SG which tests better than the '81's, but the orange and red/white wires have bullets, not the same connecter as the '81 and I don't want to butcher either right now. Maybe later.
Any suggestions to aftermarket, besides Mikes, and Michael's?
Thanks for the input.
whynot2

 

[whynot2]

Since it bothers me when someone posts a problem and leaves it hang out there with no resolution, I shall finish this so someone else will be spared the embarrassment. Yes that is why I've waited, I'm embarrassed. I missed something I should have checked.
The problem was misfiring and erratic running once the bike was hot then parked for a short time. It would start fine cold and run fine as long as I kept moving, but once I stopped and let it sit then I had problems. The solution quite simply fell off into my hands when I removed the spark plug cap from the spark plug. I can still hear an old mechanic telling me to "check the damn caps". "Yeah, sure Mike".. Well I screwed the damn thing back on and have not had a problem since.
Thank you for suggestions,
whynot 2
I shall now go write 100 times " I shall check the plug caps..." I'll put in in the lid of my tool box next to the page " I shall clean the points with solvent..."