Coils getting hot - normal or not?

I burnt my hand on one of my 850's coils yesterday. I'd ridden about 10 miles and both coils were too hot to touch. I've never given this a thought before and the bike is running fine. Is this normal or a sign of trouble?

Thanks for any feedback

Mitch

Too hot to touch is unusual. They are out in the breeze below the tank to disapate heat, but they are also designed to shed heat pretty fast. Is there anything blocking the air from getting to them? Do you still have the ballast resistor in the circuit? I assume these are stock coils, how about the ignition, are you running points or electronic??

Russ

Feels like trouble already heated them. HOT is expected if key left on in points systems so current flows constantly through one or the other coils but not both. Electro brain sparkers should cut the coil charge dwell time so merely warm to touch. I'm at a loss on what would over heat both coils while traveling and yet still run, at least to get ya stranded a ways off. In points system only one coil fires at once but on electro's both fire together so common denominator would seem to be the 'puter brain gone weird. Points usually have 6 v coil with a ballast resitor to cut their voltage from 12-ish once running a bit so coils don't over heat. Electro's eliminate the ballast to run 12v coils or coil pack. I've checked coils after running when one of them pooped out or just fell off broken mount and could handle them immediately to wire back on or tape around to insulate a shorted coil to get back on both jugs. I await a new mystery trouble shooting here to learn from your frustration.

Thanks for the replies. Bike has stock coils with Boyer analogue ignition and Boyer Power Box regulator/rectifier. No ballast resistor - wouldn't have thought it necessary with full Boyer set up?

Think I might be creating a problem that doesn't exist, 'cos I did spend a bit of time tweaking the carbs (new Amal Premieres - so far, so good) during and after the ride, so the motor was running stationary for longer than normal. I'll keep an eye on it......

Regards

Mitch

In the original coils you will see a screw on the top of the coil (well "top" if you take it off and have the wiring connections facing up).

That screw can be removed and the oil level checked. Oil is used both as an isulator and to aid in heat disapation.

Don't know that this is part of the problem, just a random thought that may/may not apply.

Another idea is to check for overtightening of the clamps. Many have shorted out and overheated from the now crushed thin aluminum bodys touching the internal winding. Only 4 lbs. torque I think.

On the 2 coils I had over tightened clamps either by me or DPO, so they shorted to the coil case, the coil did not fire the plug till it was held by hand or by tape isolated from the frame earthing. I now put a washer or two as spacers between clamp flanges where the two bolt secure to frame. I first tried just not so tight but had them vibe loose on the fly, still working fine failing banging in the breeze. Rather rare both coils going bad at same time, so think beyond coils. Its been so long since I had coil issues on Peel I'm not sure how hot they get with Black analog boyer, which I will not capitalize any more d/t its famous lets downs I had in spades.

Lucas coils have screw cap to top off but others are sealed no access to top off. The oil cools the insides out but and helps keep internal arc ing down but lack of oil would not make coils hotter than normal. I found Lucas coils low on oil when I had them off for non coil reasons and topped them off with compressor oil, but didn't notice coils too hot to handle running.

Maybe just maybe there is too much R factors in the, HT leads, plug boots and plugs so voltage/current must increase heat too much to fire a spark ?? Analog boyer fires just fine I found with no R items in the HT path. R factors in A-boyer is just to avoid annoying others electronics near by or being targeted by a drone looking for terrorists.

Thanks Guys

Pleased to report a false alarm. Been out for a long ride today and coils not even warm. Must have been the heat from the engine whilst setting-up the new carbs in the workshop.

Have to say I cannot believe the difference the new Amal Premiers have made. Straightforward to set up and it feels like a new bike - easy first-kick starting hot or cold, rock steady idle down to 500rpm (if you want - too slow for my liking) and pulls like a train through the whole rev range. I guess the old carbs were more worn than I thought.

Best wishes

Mitch

The old carbs are always more worn than you thought. Think of the violent shaking they go through ,yikes !