Yamaha Banshee magneto swap

[pdxs]

That would be great! I bought extra aluminum in case I messed up but got it right the first time. I can whip another one up in an hour or two.
I did a little work on the ignition today and have most of the toyota setup together. I am going to try and trigger a vespa coil/cdi with it since I have an extra of those and I know they work well off magneto setups. They are pretty basic with not much if any advance built in. downside of those is they are about $55 each.

I would defiantly welcome any tips or ideas on what would work best running just off the magneto. I'm really just fumbling my way through this!

[mrriggs]

I did a quick Google search on that CDI. The first page I read said that the capacitor is charged with 6 volts. That doesn't sound right. They also said it was triggered with a "Hall sensor" but the diagram shows only two leads coming from it, signal and ground. Hall sensors have three leads, signal, ground, and power. I suspect it is a VRS, same as the Toyota. Based on the diagram, and not what was written, I'd say it will work with your setup.

[pdxs]

i guess it is a hall sensor type. it does three connections (technically) . its got 2 marked verde which I know is power. one connections is power in and the other goes to the kill switch. bianco and rosso for ground and trigger and a yellow tail for another ground.
vespamaintenance.com/elec/cdiwork/index.html

I guess it wont work with the toyota parts but maybe it will with the banshee trigger mounted in their place. does the mallory/gerber setup send the same type of pulse as a hall sensor? I've been looking for dirt bikes with dual output coils but haven't come across any yet...

[mrriggs]

That is the diagram I was looking at. The "Hall" sensor in the diagram only has two connections. The text says, "The Hall Sensor measures the hall effect, the instantaneous point where the flywheel's magnet changes from a north to a south pole." That is not the "Hall effect", that is how a VRS works.

Try wiring it like this...


On the charge coil there is a red wire and a green wire. As long as there are no diodes built into the stator then it doesn't matter which one goes where.

For the Toyota sensor, it DOES matter which wire goes where and since you are the first to do this you'll have to figure it out. Unfortunatly it won't be as easy to check as it was with the junk yard ignition since you have to spin the crank to get a spark. Hopefully you haven't taken the starter motor out yet.

[mrriggs]

pdxs said:

I've been looking for dirt bikes with dual output coils but haven't come across any yet...

Since the CDI has a single output coil built in you will have to use two CDI modules. Unless you built an adapter to convert the single output to a dual output. I've never done it or seen it done but that doesn't mean it's not possible. Maybe a few turns of spark plug wire around a large toroid?



I have absolutely no idea if this would work or not.

[pdxs]

I had planned on using 2 of the vespa cdis if that works. I already have 3 bikes that run the same cdi so its just easier to keep spares around if everything stays the same.

my thought on the dirt bike stator was that it would work well with a magneto output. I have seen plenty of "dual spark" street bike heads so I was hoping there was a common dirt bike conversion that I could rob the coil from. Haven't found one yet.

thanks for the thoughts on the cdi. You've given me the insight I needed to try some things. The starter is blocked off and the battery gone. I've been kicking bikes for years so a little more exercise wont kill me. I've been push starting my daily rider since I broke the kick start off it 2 weeks ago so I can be glad I don't have to push the xs ;D

[pdxs]

No luck with the vespa setup. The vrs wont trigger it. I even ganged the power to the coil off a bike running in the driveway to make sure the cdi got enough juice.

I either need a different cdi or a hall sensor. Or a little battery to power the HEI setup.
I had an idea and hooked up the banshee pickup to the vespa cdi and hammered out quick bracket (since I hacked off the original). It made sparks just fine off the flywheel. unfortunately the banshee pickup wont quite fit under the points cover in its plastic. I'm not sure if that would work well anyway. Seems like a small shaft for the magnet to spin on.

[pdxs]

I just had another idea... I have a few old vespa cdi stator plates that I could rob the pickup off of. those are much smaller than the banshee pickup... hmm...

[mrriggs]

If I remember right, the Toyota VRS only puts out one volt at kicking speed. That is obviously not high enough to trigger the CDI. The next step would be to find out what the threshold is to fire the CDI, it's probably under 5 volts. When you know that, all you have to do is apply a bias voltage to the negative lead of the VRS. For example, say the CDI fires when the input reaches 2.5 volts. Right now you have the VRS hooked to ground so the zero crossing point is zero volts. When the VRS puts out 1 volt the CDI only sees 1 volt which is why it won't fire. Now if we hook the VRS to a 2 volt source instead of ground the zero crossing point is 2 volts. When the VRS generates 1 volt it is on top of the 2 volt bias so the CDI will see 3 volts and fire.

So don't give up yet, you have all the right parts you just need to get them talking to eachother now.

[pdxs]

sorry I disappeared. got a boat load of parts in last week so I've been working on other stuff. Fzr rotors and calipers, 81 forks (they don't drop into a 72, stem is 1/2" or so longer), 78 front hub. finally got my pile off to the powdercoater.

I realized I made a stupid mistake before when I was testing with the points. I'm not even gonna say what it was its that stupid. anyway the banshee stator setup works fine when mounted up with a points setup. fires coils green wire to coils red to ground. makes juice (yellow wire). black is ground. I could probably go out and start the bike right now (i'm tempted to...) but its on my lift with no wheels on it. wheels wont be back from the powder coater for 2 weeks! then I have to lace them and put tires on.... AHHH. this is gonna drive me nuts! I could ride it!

[mrriggs]

pdxs said:

... fires coils green wire to coils red to ground. makes juice (yellow wire). black is ground. ...

So how do you have it wired? You are running the stock points ignition off of the yellow wire? What regulator are you using?

[pdxs]

stock coils and points off the green wire with the red to ground (This may be backwards but it works). Yellow wire will power everything else through the regulator. You can run AC power to everything with a regulator or run a regulator/rectifier and run a battery. For a battery you have to float the ground on the stator.
info on floating the ground here:
www.dunereview.com/electricalupgrade-1.htm

I have both the reg/rect and the regulator from here:
www.rickystator.com/catalog/index.php?cPath=23
they are also the guys who make the 200 watt stator.

I have a bunch of stuff to play with. I don't want to run the points but it is good to know that they will work. I have all the parts for the toyota conversion now. I also picked up a 3 amp AGM battery that will be easy to hide.

[mrriggs]

I am amazed that the points ignition works wired like that. That leg of the stator puts out high voltage AC to charge the capacitor in the CDI. A breaker point ignition is generally hooked to a low voltage DC source. Your configuration is more like a conventional magneto where the rotating magnets cause an AC signal in the primary of the coil. In a conventional magneto the points must be timed so they open when the AC signal is at it's peak. You must have lucked out and the rotor/stator relationship happened to coincide with the opening points.

[pdxs]

I think you are right cause I took the flywheel off to make some timing marks and now I cant get them to fire again. I hooked it up with the agm battery for now just to start it. It started after a couple kicks, first time its ran since the PO holed the piston.

[leaddirt]

It may sound simple but my cdi on my 81 got full of water and I rewired the igition with the ignition unit from a 83 s-15 jimmy. this also got wet and stoped working. I then used a ignition unit from a 87 cadilac. one wire from battery one to ground. I cant remember the color of the pick up wires but there are three on the xs. the ignition unit has two poles in and 2 out, one goes to coil and one to power. I had to connect two of the three from the pick up together and then connect to the two poles on the input side of the ignition unit. dont ask how it works but it does. If anyone needs a drawing of this let me know and i will sketch it for ya. As to the banshee stator set up there are aftermarket one that will light up 2 150watt offroad lights. They use these for those crosscountry races.