Tutorial - YZ450F (06 & up) Electrical System For Lights

I might do exactly that. size is an issue though, wanna find the smallest/lightest possible

you don't want to do a stator rewind swatdoc?

Gray - go ahead and post that info when you can - I'm tracking down some electrical gremlins in my bike now and getting frustrated. Thinking about going to a total loss, battery only setup for my lights and am interested to see what kinda battery setup that system uses than can power a light for 3 hours.
I know it's a Li-Ion battery. Some of the high current models at the link I posted on page 8 are very interesting.

This one, for example, is rated at 6.4 Ah, and is capable of a 30 amp discharge rate. It's also small enough at 2x2.5x6 that you could conceivably get to of them in the airbox corners. It weighs just over a pound and a half.

HID lamps draw heavily as they light up, but settle back to a pretty thrifty 35 watts for an 8" Trail Tech (which is a very bright lamp) once they're up and running. At 12 volts, 35 watts is just under 3 amps. At 6.4 Ah, that's over two hours of light on one of them. And it's not the biggest unit they make, either, and the Trail Tech may not be the most efficient HID you could choose.

X - might do that too - first I gotta figure out why my bike isn't running now. After i swapped out both a new Moose stator and put the stock CDI back in, my bike started right up, idled great, and as I was blipping the throttle, it suddenly died after about a minute, and about 200 kicks later, still won't start again. Soooo, first on the agenda is putting all electrics back to stock configuration - i have a sneaking suspicion something is frying my CDI's. Has to be either electrical or carb, and i pulled the carb out and cleaned it and all the jets i could remove already.

when I get things running again, i'll prob do one of 2 things - either run a staight battery powered system, or go with a DC system that will be totally separate from the bike's ignition circuit. As it stands, the AC output of the Moose/Electrosport stator runs thru the common ground of the frame, and I can't help but start to think that may be an issue.

Gray - I think that battery would be great for a battery only system - small and light.

As it stands, the AC output of the Moose/Electrosport stator runs thru the common ground of the frame, and I can't help but start to think that may be an issue.

And you are running an AC light circuit that also uses the frame as ground? In any event, any DC system -- whether or not connected to the stator -- will not use the frame as ground, but instead will be an independent system. Not sure why hooking a DC system up to the stator or keeping it separate as a total loss system would make a difference with respect to the issue you are having. Guess I'll find out myself soon.

Couple of follow ups:

1) can you get more than 50W out of a stator rewind?

2) swatdoc, did you have to relocate the CDI in order to mount your headlight?

3) As noted above, the 5 Ah Turn Tech battery fits no problem in the airbox. It is resting just a bit on the air filter, but not enough to create any issues. I could slide it back and down to create even more room, so as I noted, I think the 7.5 Ah battery would also fit.

And you are running an AC light circuit that also uses the frame as ground? In any event, any DC system -- whether or not connected to the stator -- will not use the frame as ground, but instead will be an independent system.
I think you have that reversed. DC systems have used a chassis ground since before I can remember, while AC subsystems have been isolated from the chassis except at the ground stub of a rectifier. Only in pure AC only systems, which the stock YZ is, does one expect to see AC chassis grounds. On the other hand, it would be just as valid to keep the DC side isolated with discreet ground leads if it was being added to an existing AC circuit with chassis grounds in place.

That does raise a question as to whether there might be problems sharing a common circuit segment, such as the frame, between an AC and a DC circuit in this case.

1) can you get more than 50W out of a stator rewind?

I haven't seen anyone get more than 55w AC from a rewound YZ stator yet. That drops to around 35w when converting to DC due to losses in the rectifier.

Thanks for the clarification Gray. I guess I see no reason to use the chassis for a ground in a DC system so I just assumed it "floats" (if that is the right term to apply) -- i.e., the DC system is a closed loop to and from the battery (and the reg/rec of course) but negative never touches the frame. OTOH, on my YZ (and on other MX bikes like my KTMs) I see frame connections all the time in pure AC systems, so I just assumed in all AC systems the frame is used as ground.

Yea, I say ground, because the AC output has a black and a yellow output wire. The yellow is the hot lead to all the lights, and the black is grounded to the frame. You can run a wire from anywhere on the frame to any of the lights as the secondary power line or "ground".

I'mjust getting a feeling that since the bike's electrical system is also usingthe frame as a "ground", even thoughit's AC, that there is something being affected by having 50 watts running through the frame that the stock sytem isn't liking. Just a theory, but I think I'm gonna be isolating the 2 sytems totally from now on just to be on the safe side. I hate reliability issues, and replacing electrical components is costly!

And Lumpy - you dfinitely wouldn't want to use the frame as a ground once you've converted your lighting output to DC - keep it seperatefor sure!

You can always use the chassis as a ground. Simply becomes a shared conductor in the system. The automotive industry as a whole has been doing this for at least 100 years, if not longer. The battery is the source, in the typical DC setup, and has one lead attached to the chassis as a "ground". Then you run a power wire to a device and a switch (in either order) and at the end of that run, back top the chassis ground again. So the current flows from the source to the switch to the device to the ground, and then through the chassis back to the source. (Technically, in a negative ground DC circuit, the electrons actually flow the other way, but you can nevertheless think of a circuit logically the way it's described here, regardless of polarity).

The same holds true for AC circuits like our YZF's. Any circuit needs to be a closed loop in order to work. The chassis ground simply becomes a shared conductor, so you only have to run one wire out to any device. The snag is that in AC circuits, the polarity of any element of the circuit, including the chassis, is constantly reversing itself from positive to negative and back again. DC circuits cannot be exposed to that kind of thing. Connecting a battery to a grounded AC system would result in the negative lead of the battery being connected to a constantly alternating polarity, instead of the constant negative polarity it needs. Solid state devices that are not designed to protect themselves from AC sources the way the YZ CDI is can be blown out almost instantly by the reversion, and to a battery, it looks like an amp in, and an amp out, for a net zero.

There is no electrical reason why you should ground one circuit type and float the other. In other words, if you have both AC and DC on board, it doesn't matter which one grounds and which one "floats", or if they both float. But at least one of them has to. Manufacturers of cars, motorcycles, etc., usually just go by which circuit will need more wire to run a fully closed loop with, which is why most bikes with mixed systems from the factory have the AC floated.

What really confuses people with regard to grounds in AC circuits is building wiring and the wiring of devices made to be plugged into the wall power. The grounds in buildings are for safety purposes only, connect eventually to the earth, and carry no current at all when everything works as planned. The actual current in the building flows through "feed", or "hot" leads, and returns to the source via "common" leads. Only when the electrons get loose are they supposed to run through the grounds. Bikes aren't like that at all.

All of what Gray says is consistent with my understanding of electrical conductivity, and it's a nice write up. In summary, the chassis can be used as a ground, but only in the sense that it is just a conductivity path for either AC or DC current (but not both for the reasons he states) so that you can avoid running another wire back to the source. In my case, I have left the AC ignition circuit in its stock form and have an isolated DC circuit for the lights/horn/computer in that it does not involve using the chassis to complete the circuit. More wires but better reliability. If I ran an AC circuit for the lights etc., I would do the same thing.

Some pics:




The battery box came out well IMO. And the pigtail for the trickle charger escapes through the rear shroud hole (I have Acerbis white plastic). The IC relay for the LED turn signals is to the rear of the battery and is mounted using a single bolt through the rear fender.

The Polisport MMX headlight (35w/35w) comes with extenders so that it can be made to stick out farther from the triple clamps, thereby ensuring that the rear of the light on the inside of the mask doesn't interfere with the CDI. I didn't try the mask without these extenders b/c it looked like it would for sure hit the CDI, which others have reported with our headlight masks. The downside of the mask sticking out farther is that you can more easily see all the wires behind it, but not sure what can be done about that. I suppose I could move the CDI but that would present the challenge of where to put it. I have my reg/rec under the neck of the frame between the rads. I have seen some people put the reg/rec behind the upper most part of the skid or glide plate, so that's another option.

I don't know how to better fasten the wires coming from the tail light to the underside of the fender. I am using a couple of flexi cable holders, one of which is bolted to the front bolt of the tail light assembly and the other of which is bolted to the right side rear fender bolt. It's ghetto for sure, but I didn't want to have to put more bolts through the top of the fender itself, although that would be the cleanest way to secure the wires.

Jim - to clean up your wiring, first,get some white braided nylon wire sleeving to cover up the black wiring so it will be much less visible. To secure it better to your fender without drilling holes in your fender, go to any hardware store's electrical dept and get a pack of plastic tie (zip tie) mounting tabs. they are either white or black (obviously you'd want white) are square in shape, and have an area to run a zip tie thru. The tab mounts with adhesive tape - i removed the tape it came with and used heavy duty 3M adhesive tape they use to mount fender flares and moulding to cars - strong stuff! 2 of these mounted to te underside of your fender should work well. here's a pic under my fender - you cant's see the tab in the pic, but you can see how sleeving the wire helps hide everything.


Something else to do is trim down the plastic part of your baja designs tail light mount. you might consider painting the underside with some white Fusion paint by Krylon, again to help hide it and make it blend into the stock white fender better. here's how I trimmed the plastic on my DRZ:


Swatdoc, thanks very much for the tips. I am running an Edge 2 tail light and plate holder. I'll snap some pics. Great pic of the underside of the fender. Just what I needed. I'll get the tabs and the nylon sleeving.

doc which tail lamp is that a picture of on the under fender shot on the yz? ski

Ah OK, i assumed it was a BD light since i couldn't see the whole thing - def would like to see some pics of your setup.

Ski - the light is the baja designs LED - i just made my own custom mounting bracket.

Ah OK, i assumed it was a BD light since i couldn't see the whole thing - def would like to see some pics of your setup.

When I get the wires underneath the fender sorted out, I'll snap some pics. The Edge is a very clean setup IMO. I picked up the zip tie mounts today and turns out I already had some of the PET nylon braided wire sheathing. I plan to just epoxy the mounts to the underside of the fender. I painted my rad louvers black (Krylon Fusion, as you suggested) and they look decent. I also plan to paint the rads black with temp dispersant satin black I picked up from Eastwood. All tips I picked up from Swatdocs posts on SMJ!

I posted this elsewhere but thought it should be in this comprehensive lighting thread as well. Just FYI that I went ahead and bought the stator and FW from http://www.proracing.co.uk/index.htm. These guys are super nice and easy to work with (Nick and Bev). I confirmed that they have a separate EU manufacturer for their 50w stator -- it is not Electrex/Electrosport/Moose. Kind of like Trail Tech (which doesn't make a particular stator/FW for the '08 YZ450), Pro Racing makes a matched stator and FW that is supposed to deliver superior power over the stock FW/aftermarket stator combo. You can get the FW in stock weight, 5 oz. over and 10 oz. over. I went with stock since I have a supermoto application.

Got to be tough to clean your air filter. In my adding a wr ignition to my yz I needed a battery to make it all work. I got one throught trail tech and it looks to be about the same size as the one you are using. I had it mounted in a little pouch thing I got from them in the back side of my air box on the rear fender. That way to clean my air filter all I had to do was take it out of the pouch to easily get to the filter. But iI was still not happy with that so I moved it to inside the skid plate in front of the engine. It fit and worked fine but I really started worrying about water shorting it out. So, now it is out and tonite I am going to mount it back in the air box but on the lower right side. I think that is the answer. Out of the way, a little lower center of gravity, no air flow restriction and best of all not in the way when changing the air filter. Somebody want to pm me how to put pictures up?

Takes two seconds for me to remove the battery holder bracket (with the battery and all wires attached) and move it out of the way in order to remove the filter. Since my bike will not be seeing dirt, I won't be changing the filter as often either. But am curious to see what you come up with. I didn't think there was sufficient space to mount the battery lower in the airbox without interfering with the filter and in any event if you mount it on the side somewhere I am not sure what would hold it in place.

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