I agree with Scirocco. In theory you could do it but (and I haven't done the calculations) the capacitor would probably be bigger than the bike itself. Also, capacitors leak down over time. Assuming it was charged when you shut your bike off....it may well be discharged when you go to start it again. A good battery is a better alternative.
I have a couple of Z1B's restored, an '80 KZ1000LTD restored, a 1981 KZ550 restored and a 2008 KLR 650 for off road fun. My wife has a 2019 Suzuki DR 650 for on and off road.
hardrockminer post=846288I agree with Scirocco. In theory you could do it but (and I haven't done the calculations) the capacitor would probably be bigger than the bike itself. Also, capacitors leak down over time. Assuming it was charged when you shut your bike off....it may well be discharged when you go to start it again. A good battery is a better alternative.
And if it's not discharged, a capacitor that big could ruin your entire day VERY quickly, e.g. if it explodes (as caps sometimes do) or you're working on the bike and accidentally discharge it.
To your other point, even if the cap weren't bigger than the bike, it would probably be too big to be practical.
1979 KZ400 Gifted to a couple of nephews
1967 Yamaha YCS1 Bonanza
1981 Yamaha XT250H
1981 KZ440 LTD project bike
2013 Yamaha FZ6R
Assuming it would work, adding a capacitor would be a band-aid fix. Check & set everything as per the factory service manual and especially make sure the battery is good. If necessary, keep a good motorcycle smart charger connected. I have a Ctek US 0.8 smart charger & plug it in whenever the motorcycle isn't being used. My current battery is a Scorpion AGM & is now 3-1/2 years old. The previous scorpion agm lasted exactly 2 years, but I didn't keep it on a charger >> only charged it once a month or so w an old schumacher mc charger.
EDIT: I made a bad simplification in my math, which made my numbers much worse. I would have failed that physics test. Oops. I've recalculated with what I hope is a less bad simplification, and updated the numbers. Super caps are actually closer to viable than I had initially guessed.
Based on your formatting I was trying to find the rhyme in you stanzas.
The short answer is that batteries (chemical storage) hold a LOT more energy than capacitors (electrical charge storage). And while super caps have really big numbers (Farads!) most of them still don't hold much energy (compared to a battery), and are either very large or have high internal resistance (so you can't get that energy out quickly).
Here is the very long answer:
Random numbers for discussion. What does it take to start a motorcycle? I'm going to say the battery needs to provide 50A for 5 seconds. I'll also assume that (using magic), the capacitor starts at 14V and ends at 10V during the starting event.
You can turn these numbers into total energy required.
Average Voltage: 12 V (lots of hand waving here)
Average Power: 600 W
Total Energy: 3000 W-s, or Joules
This time I get 24,000 J, which is actually a lot. That's enough energy for 8 starts. Cool. But it's bigger than the normal battery, costs $600, and will only hold that charge for 7 days due to internal self discharge.
The real answer is lithium batteries. For the same amount of stored energy, they are lighter, smaller, have less voltage drop under load, a higher cycle life, and a wider operating tamp range.
Of course, they also like to blow up, need complicated management electronics, and can't really be swapped directly into a 12V system.
On the other hand, lead-acid batteries are filled with acid which tends to eat the paint off of old KZs, which I personally am really sick of.
But if you're looking to move away from lead-acid, lithium is the direction you should look.
Personally I just buy sealed AGM batteries, bring them inside in the winter, and from time to time put them on a Battery Tender trickle charger to keep them full. They last for years this way.
'78 Z1-R in blue, '78 Z1-R in black, '78 Z1-R in pieces
'95 GPZ1100 (sold) , '00 ZRX1100
Voltage drop at coil primaries on older bikes is often caused by the serpentine route through sometimes corroded connectors and often flakey switch contacts that carry current for other loads as well.
If, as often is the case, voltage at coil primaries is less than battery voltage at rest, that can be safely solved with a simple relay, bypassing the main wiring harness & switches to supply coil primaries with direct battery voltage. An example below: www.wgcarbs.com/index.php/using-joomla/e...-categories/89-coils
slmjim & Z1BEBE
A biker looks at your engine and chrome.
A Rider looks at your odometer and tags.