Low AC Voltage? Wuxi Nooma By fufsgfen (Read 2,101 times)

[fufsgfen]

I wish someone could give me little pointers, my moped is not exactly scooter, but before I had a scooter and this one is electrically very similar.

Model in question is Wuxi Nooma NM50, Chinese moped.

Engine is Honda 50cc copy with starter motor on top of the engine, 4 gears and manual wet clutch.

Issue I'm having is what I would guess being weak spark, very poor low end torque and cutting out at part throttle, weak starting when warm, mixture adjusting does not help much.

I get 7 Volts AC to yellow wire that is connected to Rectifier, this wire goes to lights.
From stator/magneto wires (two yellow) yellow one 15V at idle, 60V at max rpm, Yellow 2 gives 9.5V idle and 33V max rpm. Some information I have got claims that both wires should give same voltage. I have swapped wires around and not much change from that.

I'm not sure if it is full wave or half wave setup, but compared to GY6 stator this bike seems to have floating ground where as GY6 had not, but that is one thing I need help to figure out.

I have two rectifiers, testing with another gives exactly same voltages. I have added ground wires and cleaned ground contact points.





Brightness of rear license plate light for example fluctuates a lot, it gets steady with increasing rpm from idle about 100-200rpm, but then it starts fluctuating again.

If I put +12VDC from battery to yellow wire of rectifier, there is lot more low end torque, starting is easier, and it does not cut out at all when driving, feels to have more power, but I'm afraid that might burn up something, I have had such connection about 1 hour, when I took wire off and restored original connection there was again less low end torque no any new issues, but all old issues comes back.

I bought this at October and issues with poor lights were there, seller gave instructions at December to change wiring for the lights so that now headlights is connected to battery, but since then they haven't answered to my mails and are not sending parts that were broken when I got bike (I bought it new), so now I have to find what needs to be done by myself and fix then from my own pocket, which I will try to then get seller to pay.

I get bit of carb icing too, but that is cured by fuel anti freeze additive, also I have set mixture several times, checked leaks etc and all that seems to be ok now. (as new it had broken intake insulator that is between carb and intake manifold).

I guess my CDI is AC unit and it might not like from DC voltage for long, but I don't understand why adding +12VDC makes it run so much better, does it help coil to give better spark is only guess I can make?

What I think is that I would need to get somehow 7VAC to 12VAC, but as headlight is no longer in AC circuit, AC voltage is still same, no improvement.

Seller originally wrote that stator would be broken and he sends new one, but he never did that, instead instructed to change wiring for headlight, that is what I would need to verify, should I get new stator should it give same voltage to both wires?

Seller also claimed originally that headlight is in DC even I did measure it being in AC, he wouldn't believe me, then he sends instructions where he claims headlight being in AC and needs to be moved to DC, seller is nations leading expert on this model, so I guess experts here are not much good?

Sorry about lengthy post, but I guess there are still some things I forgot and you need to ask about.

[fufsgfen]

I changed rear light to 12VDC and while AC voltage is still only around 7VAC, engine starts up easier, also pulls better at low rpm with less cutting out.

What stator test videos I have seen, it looks like they always have same voltage from both wires, so I might order new stator from China unless I find something from europe. Bit unsure if that really is causing the issue, but if not, then I have new spare part and 25-30 less money.

[jct842]

I just tried to look up your bike and did not get any hits. Where did you buy it?

There used to be one fellow here who was an expert on stators and cdi and he has not posted in quite some time. With out some sort of an electrical diagram it will be tough. In our library here there are quite a few posts about electrical problems and some diagrams. If you go over all of them you may find some similarity. Should you find one to go by let us know which it is.

Are you in the USA? If you are, post the name of who you bought it from so some one else does not get into the same situation. It seems strange the seller would be instructing you to change wiring on a brand new model.

[fufsgfen]

Feb 28, 2017 13:07:19 GMT -6 jct842 said:

I just tried to look up your bike and did not get any hits. Where did you buy it?

There used to be one fellow here who was an expert on stators and cdi and he has not posted in quite some time. With out some sort of an electrical diagram it will be tough. In our library here there are quite a few posts about electrical problems and some diagrams. If you go over all of them you may find some similarity. Should you find one to go by let us know which it is.

Are you in the USA? If you are, post the name of who you bought it from so some one else does not get into the same situation. It seems strange the seller would be instructing you to change wiring on a brand new model.

I'm in Europe, Wuxi Nooma is Chinese manufacturer of bike and it is sold under various names around the world (like Baotian). For example Jingchen Q7 has similar engine and I guess part of electrics, but that is still different so much that 139qmb diagram is almost as little help with wires and I don't know if that is any more familiar model in US. Anything with Chinese Z50 clone engine would be actually similar.

Seller is not giving electrical diagram and Chinese manufacturer refuses my request of diagram, but I have somewhat charted out wires already, wiring is quite simple actually.

I would say one should stay clear of Wuxi Nooma made bikes, quality is quite bit worse than Baotian, this is bike model and manufacturer which I managed to trace:
wxnuoma.en.alibaba.com/product/1843053901-219362926/hot_selling_50cc_110cc_chopper_motorcycle_NM50_C.html

I just found out that seller has sold his whole business to bigger supermarket chain, that might not be any good for my situation and might explain why so poor customer support, they did run out of money probably or knew they don't need to do anything as they get out of the picture, great.


If I could find out if my stator is full wave or half wave, then I could probably get new parts ordered from China and see what happens, I'm stuck with this anyway. Another possibility would be to put in new bigger motor (around 300 here) and be done with it, 50cc is bit slow at hills anyways.

[jct842]

How many wires and what color are they. There are several common configurations.

as an example 3 yellows indicate a 3 phase stator. In any case there are some tutorials for checking stators and what ac voltage to expect that are in the library.

There used to be a link at the top here for this forum,
49ccscoot.proboards.com/ They may have the help you need.

[fufsgfen]

Feb 28, 2017 17:03:14 GMT -6 jct842 said:

How many wires and what color are they. There are several common configurations.

as an example 3 yellows indicate a 3 phase stator. In any case there are some tutorials for checking stators and what ac voltage to expect that are in the library.

There used to be a link at the top here for this forum,
49ccscoot.proboards.com/ They may have the help you need.

Two yellow, which are typically yellow white, but in this both are yellow.

Yeah, three yellows are in bigger motors, this is almost same as GY6 50cc, but difference is that stator windings are not grounded to body.

Yellow from regulator/rectifier (Regulated voltage, I guess it is AC) is what is connected to one yellow at stator and also to lights, another yellow from stator continues as white to regulator/rectifier (AC output to).
Red from regulator/rectifier goes to battery, that is regulated 12VDC, then green from regulator goes to ground.

There was other wires in stator too, rpm signal was one I think, neutral gear indicator it will start only on neutral and rest can't remember, must check tomorrow when it is light again.

Basically, if I understand correctly, system is similar to dirtbike/pitbike, where there is light coil and charging coil, this one has 6 pole stator which 2 are light coils I guess?

When I have all lights connected to battery (DC circuit), there still is plenty of charge, 14.7V at 2000rpm or so, so lights are not much of problem, I can keep them at DC, running leds anyway, but ignition is bit more of problem, it does work much better when all lights are connected to DC, but still AC voltage is low and I haven't used it enough to be 100% sure cutting out was cured, all rides I have done after change have gone flawlessly though so no more cutting, but well see.

I have checked stator by instructions, it is single phase I guess and I don't get even close to same voltage from them, but would I get if there are 2 coils for lights and 4 for charging?  edit: oh, now it hit me again, do I have 2 or 1 for lighting, my memory is shorting out, I guess I check that too tomorrow.

Every year brain starts to be more foggy, so I might get things wrong way quite often already, never really have understood bike electrics so things tend to be confusing even more because of that, but with enough crashes to walls I end up usually to solution

edit: What confuses me is because there are stators that are exactly like mine like this:
www.motopartsdealer.com/6coil-fullwave-magneto-stator-for-50cc125cc-electrical-start-atv-dirt-bike-go-kart-p-1456.html

It says full wave, there are also regulator/rectifiers that look exactly like mine and those are full wave too, but if my parts are full wave, then why light coil and why it connects to regulator which makes it 7 Volts AC, that creates confusion.
With full wave, I would except both wires from stator to go to rectifier and nowhere else.

Then power to CDI, it might come straight from one of the wires of stator, that is what I need to check tomorrow as my failing memory fails me again probably.

[fufsgfen]

I'm now even more confused, CDI seems to get power directly from the stator, is this then 3 phase with 2 of the phases being regulated and one running CDI unregulated?


It makes even less sense to me that one of the yellows is tapped to run lights (not anymore really as I run lights from battery).

Between two yellows there is very low resistance, between yellows and ground there is no connection.

Between black with red stripe and ground (green) there is around 500ohms, no connection to yellows.

I still have lights running completely from battery and again engine started much better than before when rear lights were connected to one of the yellows, I don't know what is happening really, but I think that now as yellows are not connected anywhere else than a regulator/rectifier there is nothing to confuse phases, but is that real reason or is there something else to this?

[jct842]

scooterdoc.proboards.com/thread/6179/generic-150-diagrams-dc-cdi

[fufsgfen]

Mar 1, 2017 11:56:01 GMT -6 jct842 said:

scooterdoc.proboards.com/thread/6179/generic-150-diagrams-dc-cdi

Thanks, my CDI is AC version and seems to run directly from stator AC voltage by black wire with red stripe, single 6 pin connector with 5 wires in CDI end.

Other than that, colors of that diagram seems to be matching to function of wires what I have, even yellow wire to lights, weird stuff!?

What I'm thinking is that reason for yellow wire to have only 7 Volts AC is because it is only half, I might be wrong, but I think that yellow + white (which starts as another yellow) together makes 14 Volts and each only 7 Volts, both go to rectifier which makes 14.7V DC out from them.

One yellow alone can't put out more than 7 Volts then or maybe I just don't get it at all how these things work, but that is what I have measured from those wires.

Then there is black with red stripe that goes to CDI, that is other half from the stator I guess, because it is 30V on idle, so there are 3 phases on stator after all, I guess?

Do CDI units usually run on unregulated AC? That is lot of voltage, imo.