Franken 550

Hmmm, i feel like it wouldn't be an issue 99% of the time as the engine would have to be turning with the ignition off, which would be rare, but maybe i should do it to be safe. Why would you coast down hill with the motor off? you'd still be pulling in fuel.

The cap battery was totally dead and as i first attempted to start it last night. kicking would keep the dash lights on but didnt have enough juice for the headlight or the ignition coils so I had to charge the caps a bit and then it kicked right over. The aftermarket LED headlight i put in acts kinda weird in that it doesn't seem to turn on till the bike is running. I'm thinking it has some sort of smart circuitry.

I might just keep a lipo around to quickly jump the caps up to 12v if it ever dies. I went full LED so i have little parasitic draw.

Now if it didnt start snowing last night.... gah!

Some people fool around with the kill switch in tunnels etc to create a big backfire. And other tom-foolery.
It can also happen if the throttle were to get stuck and the motor red-lined and you kill the ignition. The alternator would still be putting out a lot of power as the motor slowed to a halt.

Capacitors will drain pretty much instantly. They do not hold any significant charge compared to a real battery. It's the alternator that provides all of the energy. In one kick, the alternator/rectifier has to fully charge the empty capacitor and then give power to the ignition. It can do it easily if the kick is fast enough, but not if there are lights on. Lights act like a dead-short until the filaments heat up and start making light.

The capacitors are really just acting like a filter so the regulator can regulate properly. They are not meant to be a power source.

The portion of the kick required to charge the capacitor will vary depending on the size of the capacitor. If the cap is too big, it might not work, but it would have to be really big for that to happen. You can always add a little 9-volt battery to charge the cap through a diode for safety. But I haven't found that to be necessary.

I definitely have too large of a capacitor bank. I sized it for the 550 when I still had a starter. Its rated at 16v Max and 83 farrad. A bit of math and that's about a 330mAh battery.

I can't take any cells out because they're 2.7v cells wired in series to be safe at these voltages.... I wonder what the ideal size is for a motorcycle with LEDs and kickstart only...

Edit: hmm actually I could probably measure the power usage of the bike while running off of a battery and use that to find the ideal size.

Saablord wrote: I definitely have too large of a capacitor bank. I sized it for the 550 when I still had a starter. Its rated at 16v Max and 83 farrad. A bit of math and that's about a 330mAh battery.

I can't take any cells out because they're 2.7v cells wired in series to be safe at these voltages.... I wonder what the ideal size is for a motorcycle with LEDs and kickstart only...

Edit: hmm actually I could probably measure the power usage of the bike while running off of a battery and use that to find the ideal size.

I guess I don't know what you are really using. A simple capacitor doesn't have cells. All you should need is a single 50v capacitor in the range of 5000 to 10,000 micro-farad. 83 farads would be 10,000 times more than you would need. The voltage rating on a capacitor is not the voltage a capacitor provides, but is the maximum it can safely handle. Because of possible over-voltage issues and because it's easy to get caps in higher voltages, 50v to 75v makes for a good safety margin over the expected 14v it will likely handle.

The capacitor typically, when used in our bikes, is not an energy storage device. It is a ripple filter, like any other ripple filter on a classic power supply. The energy comes from the alternator in pulses. The capacitor just filters the pulses so the regulator can regulate it properly.

Here's the one on my bike. I actually installed two, but only one is connected. The other is a spare. I think they are either 5000 or 6000 micro-farad (uf). I installed these 10 years ago and have never had to use the spare. The bike sits in an unheated garage, in subzero temps during the winter. These are cheap (relative to batteries) industrial capacitors, around $20 new, but are good quality ones. I think the light blue one is a Mallory made in the 1980's or 1990's and were used 10 to 20 years before I installed them in the bike.



If your 650 has a 3-phase alternator (3-yellow wires) then you would probably use about the same size cap as I did.
If it's a single-phase (2 yellow wire), then you might be able to use that size or may want to get a slightly bigger one. Maybe 8000 to 10,000 uF.

Something like this:
www.digikey.com/product-detail/en/vishay.../4334PHBK-ND/2258685

Haha, sorry, cells was the wrong term. I am using this:


Capacitors in series you add voltage and 1/(1/c+1/c.....) capacitance. so i have a safe limit of 2.7v*6 =16.2v. and capacitance of 1/(6*1/500F) =83F. I know this is large and at this point it is more like a battery. I measured the voltage the next day after running it previously and the voltage was 10.5v. This is more of a car battery replacement and i bought this to handle the 550 with a starter. Ill probably eventually buy a starter for the 650.

The estimation for the equivalent battery size is based on capacitors being a linear device whereas they are clearly not as energy stored decreases significantly as voltage drops. Also, micro farad is 10^-3 farad so a 5000 to 10000uF are 5 and 10 F. So they are 16 or 8 times smaller than mine.

Again, sorry for the confusion.


Anyways! The bike! I flushed the water out of the tank (cleaned it one last time before install) and carbs so that the damn thing would actually run right. It also started a bit easier when the carbs were actually delivering a combustible liquid, haha. The tach is still stuck but i think that has something to do with the sub freezing temps and some lube would help.



Some videos:
walkaround
some revs

Dang, I freaking love these noises.

Saablord wrote: H
The estimation for the equivalent battery size is based on capacitors being a linear device whereas they are clearly not as energy stored decreases significantly as voltage drops. Also, micro farad is 10^-3 farad so a 5000 to 10000uF are 5 and 10 F. So they are 16 or 8 times smaller than mine.
.

Micro-farad is actually 10^-6, farad not 10^-3 farad. 5000 uF is .005 farad.

Saablord wrote: H
The estimation for the equivalent battery size is based on capacitors being a linear device whereas they are clearly not as energy stored decreases significantly as voltage drops. Also, micro farad is 10^-3 farad so a 5000 to 10000uF are 5 and 10 F. So they are 16 or 8 times smaller than mine.
.

Micro-farad is actually 10^-6 farad not 10^-3 farad. Thus 5000 uF is .005 farad.

The bike sounds great!

Ah crap, my bad, brain fart.

I didn't get all the water in the tank apparently though so its drying out for a while. Now I wait for ride-able street conditions

Using the 550 carbs wasn't workign out so i bought some 650 (vm24ss) carbs and fixed them up.




I was going to put the carbs on the bike but it was so dang cold the carb boots wouldn't slide on.

A few hours and some cursing and this thing is running like a top! Had to fix a severely cracked overflow tube and do a second cleaning of the passageways.

The weather was threatening snow tomorrow so I enjoyed a quick zip around the block (at 11pm, sorry neighbors). So now I'm just waiting for the new plates and I can fine tune the Jets until then. And I have an AFR gauge so I can do it the easy way :laugh:


Oh and I still had to use a heat gun and a lot of grunt to get those carbs to fit the boots!

FYI those are not Mikuni VM24SS carbs. They are Mikuni VM22SS carbs (22mm). They were used on the 1978 KZ650-B2A and D1A models. Ed

Gah! I wasn't gonna mention it but now.... I bought these on eBay and the part number was for the 79 model, so that's just another thing the seller lied about.

It was.listed as in perfect clean condition besides having a broken fuel screw but when I got the carbs, there were no top cover gaskets, no bowl gaskets, the fuel tee leaked, a leaking over flow tube, a broken choke lever and they we're definitely not cleaned.

I got a partial refund so it only cost me $30, but I had to spend $70 in parts and hours fixing them!

Whatever I guess, they run great now, and I shouldn't be too surprised for eBay stuff.