what problems can a bad stator cause

[jason3249]

Hi all just wondering what problems can a bad stator cause


Thanks all.

[WD Forte]

Basically.
It wont/cant charge the battery.
This means the battery is the sole supplier of electrical power and
soon goes flat.

Occaisional stator testing is pretty quick and easy
and knowing how to do this realy helps as sometimes
it isnt the stator at fault, but a bad battery or connectors and wiring


While I'm rantin on....
there are stators and stators
A bike with CDI ignition may have a 2 part stator
where most of the windings generate power to the battery via the Rec/reg and have another part, say two coils that power the ignition

Sometimes it may be just the generating coils that fail, sometimes the CDI source coils.
If you know your bike, pinning down the culprit is pretty quick and easy.
____________________
bikers smell of wee

[Islander]

Yep, this. ^^

You can test the output using the AC ranges of a multimeter.

[WD Forte]

Just had alook for some pics
Heres a typical 'charge only' Bike stator
https://thumbs1.ebaystatic.com/d/l225/m/mSYmZ-IMwSmIsXYCzhIySYA.jpg

The first test I do is measure the resistance between all pairs of the yellow wires.
You want to see very low resistance between any pair < 1 ohm
and very high resistance between any wire and the stator body
which is earth or ground.
You want to see megaohms or off the scale here.
Anything in between is often suspect in my experience

If you can disconnect the stator when the bike is running
you can measure the AC voltage between pairs at tickover
and may get around say 20VAC.
This voltage will rise to possibly approaching 100VAC when you rev it
on a healthy stator.
This all depends on the size of bike and stator of course.

Testing and recording your results when its all going well gives you
a reference point for later if it starts to play up.
____________________
bikers smell of wee

[ZebraDriver]

Came across this site the other day. It gives a very clear/concise description of how to find/identify charging faults

https://www.crowitis.com/images/fault_finding.pdf

If you can print stuff its probably worth printing it for the day when you do need it.......


ZD

[jason3249]

Can a bad stator cause back firing and out the carb spluttering and the bike wont run right rev bog etc

[Kickstart]

Hi

Possible, but probably not that likely. On some bikes the stator contains parts of the ignition system, on others little more than the charging circuits .

What bike is it?

All the best

Keith
____________________
Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[ZebraDriver]

A faulty reg/rect, allowing the charging voltage to climb beyond normal limits will cause the symptoms you list.

[jason3249]

It's only a pit bike I got yesterday I've changed the carb to a new one fresh fuel new plug new cdi

The only one I haven't dun is the voltage regulator

But I have tested the batt wires and I'm getting normal voltage and the batt is new

Another problem keep on getting engine what don't work but did know there was a problem as brought it as a non runner got it to this stage


So you think I should change the voltage regulator as there cheap are get one tomorrow and just to be save are get a stator



Just splutters bogs back fires and out the carb just looks like compressed air coming out but getting flames out the exhaust does idol if I turn the screw up so it has to run high and it will stall out and it keeps kicking back and it hurts my foot is feeling it


What else you think it mite be

[RhynoCZ]

[ZebraDriver]

Nope. If it breaks down it can start to let more and more unregulated voltage through. When my reg/rect broke down recently I was measuring more than 18 volts across the battery. At that voltage things like the coil and ignition system start to malfunction, hence you can get shitty running, backfiring etc. It can also fry your battery


ZD

[RhynoCZ]

[ZebraDriver]

Yes, the rectifier is a device that converts AC into DC. The regulator is what holds the voltage output at a steady (suitable) level. On most modern bikes there is a combined rectifier/regulator (reg/rect). The individual component parts can break down so that you still get a DC output but it's not regulated to the correct voltage.


ZD

[ZebraDriver]

It gets more complicated than being a single diode. A lot of bikes have a three phase alternator and have a diode bank to convert this to DC for the bike to use. Rectified three phase is better because it provides a smoother DC. Because it uses a bank of diodes it is possible for one or more to break down, but not all of them, this can produce some strange electrical gremlins.

Having said all of the above if the OP's bike is a pit bike I would guess that it probable does not have a three phase alternator, more probably a single coil, with a second coil for the ignition circuit.

ZD

[Kickstart]

Hi

Regulator / rectifier units tend to be combined and can fail in a few ways. I have had them stop charging totally, and also had them send the voltage too high (which can fry other components). Never had one fail and give out AC instead.

As to the pit bike, I would like to see a wiring diagram for that particular bike. My guess is that the stator includes the charging circuits and the trigger for the ignition. Could be worth trying a timing light on it and checking that the timing is correct.

All the best

Keith
____________________
Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[MartQ]

A diode is capable of failing in two ways.

Most commonly, they go open circuit and therefore do not allow any current to pass at all.

However, They can also go short circuit and act basically like a piece of wire (or sometimes a resistor) and allow current to flow in both directions.

This can cause either no (or insufficient) charging, or indeed, overcharging.

[jason3249]

It was the stator its running now you can ride it but does keep bogging and dying out some times at hight speed

But does start well now and idols fine revs up just bogs some times and at mid range

What you think on that

[MartQ]

Could be a failing CDI unit or carb set up.

I would suspect the CDI though if you've been having electrical problems as one fault can quickly cause others further down the line.

[jason3249]

All ready tried a new cdi been playing with the carb but cant get it any better

gone try the needle settings 

Put new gaskets on the inlet manifold 

Have played with the carb does get a little better but cant get it bang on