Ignition system questions on Buddy 50

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I guess I'll just drop my specific questions right up front, and then if you want to know the full story you can read on about the diagnostic hell I am currently going through.

-I can't find specs on the pickup wire (blue/yellow coming off the stator). I'm reading only 0.1~0.2V while cranking the starter. Is that too low or is it fine? Should I try to adjust the gap of the pickup?

-According to the wiring diagram in the service manual I am looking at (http://modernbuddy.com/pdf/buddy50_service_manual.pdf), that blue/yellow wire goes directly into the CDI. The thing is, my CDI only has 4 wires going into it - red, black, red/black, and blue/white. I looked to see if the blue/yellow had somehow escaped from the connector, and I even cut back the tape a little ways on that pack of wires, but couldn't find it. It doesn't look like it was ever there. Is that normal? Also on a related note, while I was testing for voltage from the ignition coil terminals, I was getting a little blip of something there but then looked back and noticed my stator was still disconnected from when I was looking at it earlier. It spooked me at first, thinking how can I be getting voltage from the CDI output if the trigger wire isn't plugged in??? But considering the other end of that blue/yellow wire is MIA anyway, it makes me think that maybe the bike somehow just doesn't use that wire to determine timing for some reason. It doesn't make sense to me, but I'm in over my head here.


So if you want the long story - back around January I took the bike out of town to visit a friend. When I went to leave, the bike wouldn't start. It would crank, but not fire. Sure it was cold out, but I've started it in worse weather without a problem. I ended up having to leave the bike there overnight and my friend took me home. The bike has 13k miles on it and this is the first time it's ever stranded me like that. The next day I tapped another friend who has a truck, and she took me to pick up the bike. For shits and giggles I cranked the starter, and it started right up, so I just rode it home and chalked it up to the cold and maybe the weird incline of my friend's driveway where I had parked it.

Maybe a week later, I rode the bike to church, and came out after service, and it wouldn't start again. This time I had to push it back home, uphill, in the cold, through the snow, and that reeeeaelly sucked. When I got it home I pulled the spark plug and it looked pretty fouled with crusty carbon buildup and also what looked like a bit of dirty black oil residue. So I walked to Auto Zone and bought a new plug, and it started up immediately. I couldn't remember the last time it had been replaced so I didn't think much of it and figured I had fixed the issue.

And then it was fine up until last week, when it stranded me for a third time, and I had to push it home again. I pulled the plug, and it looked blacker than I had expected for a plug that had just been changed, and thought maybe there's something else going on that I should be looking at. I went to Auto Zone and bought another new plug, but this time it didn't come back to life and I haven't been able to get it to fire since then.


I have spent all week tearing it to pieces in my garage trying to pin down a diagnosis but can't figure it out. The battery is not healthy, but I normally kick start. It does sit above 12V and it is enough to run the lights and get a few solid cranks out of it before needing a charge. The electric starter works fine, so I'm assuming I can rule out the ignition switch and killswitch, but someone feel free to tell me if I'm wrong on that. I'm getting 30~50 volts on the red/black (ignition charge?) wire when kicking/cranking the starter, so I would think that should be enough to charge the CDI. My ignition coil is looking a little worse for wear. The resistance readings are about 8.9k on the cap, and 0.1 ohms on the primary leads. Although I couldn't find exact manufacturer specs for the Buddy, other generic information and forum posts I found around the web suggests this is about normal for a coil on one of these machines. I am also getting a blip of a voltage reading across the ignition coil terminals when cranking the starter. My meter reads randomly anywhere between a fraction of a volt and maybe 4 volts. I am getting similar readings from the cap. Now according to what I have read, you need a tool called a peak voltage adapter to read those momentary discharges from the CDI to the ignition coil. Unfortunately I don't have one of those, so the best I can say is "it's doing something" but not resulting in a spark. I have tested the spark plug itself (well, all 3 of them that I now own) in the cap by holding the plug against the engine or another ground while cranking the starter, but I have not seen it spark. Whatever other issues may exist, I really need to get the bike running at least so I can go grocery shopping. I'm hoping if I throw a CDI + coil at it, along with the new spark plug, it will fix the problem... but I have not been able to find a smoking gun to say that either of those components are definitely bad.

Last year I had the regulator/rectifier go bad and I only found out when my battery went flat and my lights stopped working. The dealer sold me another bad one for like $40, which instead overcharged my battery and blew my headlight. I took it back to the dealer and told them it was bad, they charged me a restocking fee to return it, and also charged me for a new headlight, and then I assume they put the damn rectifier back in the stock bin to sell to the next poor unsuspecting sap. So I figured if I'm going to be rolling the dice on unreliable parts, I might as well just try one of the $8 ones from amazon instead of letting the dealer rip me off. I bought this along with a volt meter that I wired in place of the USB port so I could keep an eye on it, and that has worked fine ever since. The whole incident has me wondering what other latent electrical failures might have been caused by that whole overvolting episode though.

If taking the bike to a real mechanic was an option, I would be all over it. I could go on a whole rant about the dealer, but bottom line is it's just a proven waste of time and money dealing with them. So I am basically on my own with this bike. I've already been down there to try and buy a coil + CDI, but they didn't have either of them so I am going to probably have to order from Scooter Dynasty and pay up the ass for fast shipping.

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Okay I looked at the cranking voltages again this morning on a fully charged battery and got 68VAC on the exciter coil, and 0.2VAC on the pulser pickup. Resistance on the pickup measured 112k. I don't know if these pickup numbers are good or bad, I'm curious if anyone else can provide a reference value for these from a working system.

Either way, I can't even tell if or how this pickup is even used in the system. That blue/yellow wire just seems to disappear into the harness somewhere, and doesn't come out anywhere else. The CDI output will still produce a "blip" on my meter with or without the stator connected. How does it know when to trigger if the pulser is not plugged in? Given the "blip" I would like to be able to say that everything upstream of the CDI is working correctly, but maybe the CDI is not putting out strong enough voltage, or the ignition coil is somehow not stepping up the voltage to produce a spark. I would really like to solve this mystery of the blue/yellow wire because unless I understand how the pulser pickup works and exactly where it's connected, I don't think I can rule it out. Can anyone shed any light on this?

My dealer does not keep any Genuine parts on hand so I'm probably going to have to bend over and have parts 2nd day shipped to me from Scooter Dynasty. Seems like I can't get out of a position of having to shotgun the issue, so I'm going to order a CDI and an ignition coil for sure. The stator is much more expensive and also inflates the already wild shipping prices, so if I can at least rule that out it would be huge.

All this cheap electrical junk I am replacing on the Buddy looks for all the world nearly identical to the impossibly cheap GY6 junk you can have overnighted from Amazon for a fraction of the price, and I've been really tempted just to try it and see if it fits. Don't get me wrong, I love my Buddy, but I don't understand why it has to be so difficult to get parts for the Buddy without waiting weeks on end. Say what you will about the Chinese bikes, but if I had a Taotao right now I'd have had this issue fixed last week with minimal interruption to my life and livelihood.

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Not sure if nobody knows this stuff, or just hasn't seen it yet, or doesn't really care about it, but I guess I'll leave my experience here for anyone on this path in the future.

Found a different wiring diagram (http://www.epfguzzi.com/scooterpunks/ma ... wiring.pdf) that looks more like my Buddy with only the 4 leads going into the CDI. It shows the blue/yellow wire is actually terminating at both the ignition switch and the killswitch. The killswitch just grounds out the signal, and the ignition switch connects it to the blue/white wire which is how the timing signal ends up in circuit with the CDI. This is a different setup from the Ligero 50 model's diagram that has been linked on this site before. Interestingly but also unrelated, the starter is nowhere in circuit with the killswitch, which is a surprise to me; I assumed the starter would not crank with the killswitch off. I guess maybe I somehow have never made the mistake of trying it, but now I want to, just to see.

I verified all of this on my Buddy by checking continuity with all switch positions. While this information does help me to rule out the switches with a little more certainty, unfortunately I still don't think I can rule out the pulser coil. I wish there was some way I could generate a little bit stronger pulse signal from some other source, such that I could be reasonably sure the CDI should be discharging to the ignition coil. If I can get a spark that way, I think that proves it's the pulser pickup. If not, then it's still either the CDI or the ignition coil. Either way I would have fewer parts to have to order.

So now that I know where that blue/yellow wire goes, there is still one other mystery, and that's the blip on the CDI output even while the blue/yellow wire is unplugged and the CDI should have no timing signal. Will have to test that again just to make sure I am not going crazy, but I wonder if it is creating weird voltages on ground when unplugged, and somehow triggering the CDI to discharge anyway. Actually that gives me an idea... I would like to be able to pull the pickup off and completely away from the rotor and see what happens. If the blip goes away, I think that can prove the CDI is at least triggering, and the no spark problem is probably the main capacitor in the CDI or else something with the ignition coil. It's frustrating that I can't get a peak voltage reading with my meter. I'm half tempted to just run a couple wires from the CDI and hold them in my mouth just to see what happens. If the voltage output is strong enough, I guess I'll know it's the ignition coil.

The little bolts on that coil are on there really damn tight, though. I am actually kind of terrified to take those off, because I already tried and failed. I would probably have to use my breaker bar, but with that kind of torque I am afraid the heads would just twist right off and then I'd be really screwed. Thoughts, anyone???

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Turns out Big Clive of youtube fame reverse engineered a Chinese CDI a few years ago, it's very interesting. https://www.youtube.com/watch?v=R1wrrsb3RDk. People say these are not interchangeable because they are finely tuned per engine, but after seeing how they work I am skeptical of that claim and even more tempted than ever to try a cheap AC GY6 one.

The current from the exciter coil is rectified via a diode in the CDI and continues in circuit through the capacitor and the ignition coil primary winding. That would explain the blip I am seeing there even with the trigger pickup unplugged. So I think the capacitor has not gone open, but that doesn't mean it didn't fail in some way.

Theories:

1. The capacitor has leaked or somehow lost capacitance due to stress over time and the spark weakened. Maybe that's why the bike was fine for a short while on a brand new spark plug after the first incident.
2. The capacitor is not being triggered to discharge. Could be either due to a fault with the pulser pickup, or the sensing circuit in the CDI. So it could still be either of those parts and that doesn't help me eliminate anything from my order. I really need a way to generate a pulse to feed directly into that blue/yellow wire. If I can force a spark, I can be pretty sure it's the stator/pulser pickup. If I can't, then my pickup is probably within spec and it's going to be the CDI or ignition coil. I wonder if I can just wire in a small battery and tap a lead somewhere to emulate a signal.

(a few hours later)

Had another diagnostic session after church, measured the pulser pickup again on a full battery, and I definitely saw it peak at a little over half a volt. At this point I'm leaning towards the CDI. However, the coil fails visual inspection due to some cracking and deterioration of the boots. I don't think it's necessarily affecting the functionality of the coil, but it could stand to be replaced anyways and then I'd have an emergency backup as long as my old one still works.

From a tools standpoint, I think I may grab one of the cheap chinese CDI's off amazon too. Even if the timing is wrong for my engine, I don't think there would be any harm in using it just to test the ignition outside the cylinder. Would have been a great diagnostic tool to have handy. Wish I knew someone with a cheap scooter that I could borrow from. An oscilloscope, a peak voltage adapter, or maybe just a nicer automotive multimeter with these features would have been nice too. Given all of the electrical problems I have had with this damn bike I should probably invest in one.

I should also try and keep my eyes open for a cheap project bike---a GY6---and get it running as a backup so I don't end up in this absolutely crappy, unbearable, depressing situation where my bike decides to quit just as the weather starts warming up, and I'm having to wait on Buddy parts for weeks on end or else paying absolutely wild shipping fees to get them in a reasonable amount of time. Having thoughts about flipping the Buddy and just picking up several Chinese bikes... but I really don't want to.

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Double checked the timing signal and exciter coil again yesterday, and definitely got over 500mV peak on that signal, as read on my cheapo meter. Hopefully I've correctly ruled them out but it's hard to tell without published specs. I went ahead and ordered a CDI and ignition coil from Powersports Outlet. If I can confirm the CDI failure I'll probably try to de-pot it and leave photos for the community. I bet it can be matched to a cheaper alternative, and they might be worth rebuilding, or maybe cheap to outright fabricate for someone with those skills.

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Looked at my stator again, and found that it has a ground somewhere in one of the charging coils. I ordered a cheap CDI from Amazon just to confirm the CDI failure, or to see if I needed to go back and add a stator to my order of Buddy parts. The cheap CDI arrived in the mail this morning and I'm relieved to say it is now sparking strong. I installed the plug and let it idle for a few minutes just to be sure the ignition parts of the stator were working. I don't know if I want to actually ride the bike with this CDI in it until I better understand how the timing bit works. The Buddy parts are still on order so it's going to be a while before I can get it back on the road.

I know people will often just shotgun these ignition issues and blindly replace all the parts. So after all this time and work and anxiety and hand wringing over which single part was bad and how much it's going to cost me to get spark back, in the end it turns out to be a bunch of independent failures of basically the entire ignition system. In the end all I did was waste my own time by not shotgunning it. I would chalk it up to some kind of freak statistical improbability that all of these parts would independently fail at once, but when I think about all of the electrical problems I have had with this bike it's not so implausible after all.

-spark plug fouled - suspect cylinder may be dirty inside with carbon buildup, need to look into that
-ignition coil deteriorated. just wear and tear.
-CDI box ceased functioning...just because?
-stator charging coil continuous to ground. doesn't look burned or worn out. no idea.

The stator is less pressing in any case, because I think it will be fine for short trips to the grocery store, etc. Besides, trust has been broken now and I don't plan on taking it far from home anytime soon. Since the stator is a more expensive part, and I"m already beyond my budget right now with this bike, I'm thinking I might just try to re-wrap it myself if it becomes a bigger problem. This bike is going to eat me alive if I let it.

[sc00ter]

I skimmed your post. First thing, don't order from Scooter Dynasty. They don't always ship what is pictured. Order from a company that deals with Genuine, like Scooter Works.

Second, IF the stator is bad (rare on a 50cc) then get a NCY brand aftermarket one. The early 125cc Buddy was known for premature stator failing and NCY makes a affordable replacement with good quality.

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I skimmed your post. First thing, don't order from Scooter Dynasty. They don't always ship what is pictured. Order from a company that deals with Genuine, like Scooter Works.

Second, IF the stator is bad (rare on a 50cc) then get a NCY brand aftermarket one. The early 125cc Buddy was known for premature stator failing and NCY makes a affordable replacement with good quality.

Thanks for the warning, I will have to remember to steer clear of them. I ended up ordering from Powersports Outlet which appears to be a Genuine dealer in AZ that is cool enough to ship parts out. They were a few dollars more, but they shipped it USPS Priority $10. A price I'll pay to avoid my local dealer.

Scooter Works is usually the first place I check for anything, but they did not have these parts listed. I also looked for the NCY stator specifically but could not find a Buddy 50 version of that anywhere so I wasn't sure if it even exists or not.

Anyway, the parts came in (ignition coil + CDI) this afternoon, ahead of schedule somehow. They came in sealed PGO bags so I guess they're the real deal. The ignition coil is reading 0.7 ohms on the primary side and something like 7.7k on the secondary, compared to 0.1 / 8.9k on my old one. I still don't know what the specs are for these things although the 0.7 is more in line with the general numbers people seem to throw around so probably a good thing I replaced it. In any case the bike started on the 1st kick with the new parts. While it's too cold and wet today to go for a ride, I did take it for a short spin down the street and everything seems back to normal. Case closed, I hope. Although I still don't know the reason my stator seems to have continuity to ground, but it's charging the battery at 13.5-14V. Everything I have read says that a grounded yellow wire on a stator is bad. No idea, can't explain it. Not super worried about it as long as the ignition parts of it work.

[DeeDee]

Sooooooooo many words. Is there a cliffsnotes version?

[sc00ter]

It's been awhile since I've worked on a Buddy 50 but isn't there a "earth ground" that connects to the transmission case? I seem to remember forgetting to re-connect that and weird things happening.

Anyways, check that ground.

And Power Sports Outlet is a good place to order from.