Hello guys,

Currently I've been working on the charging system on my bike. My magneto broke so I've ordered new one. When it arrived i opened the case to find out that maybe the stator is not in line with the magneto which may caused the previous magnet to break. After installation of the magnet I've noticed random bumps when the engine is idling ( like sudden stopping and skipping a beat ) which was probably the magnet hitting the stator coils. Since the generator was not charging the battery ( rectifier outputs only 4VDC ) I've opened the cover again to find out that the stator is twisted, deformed and also in short between all three wires. I've decided to remove the stator to eliminate more damage to the magneto and continue to use the bike with charging the battery from home while the new stator and generator cover arrive but the bike wont start without the stator coils. I've reviewed the wiring diagram and I can't find out what the coils have to do with the ignition. Since the pick-up coils are on the other side of the engine im not sure why the engine wont start. The bike is 2004 GS500F.

The ignition simply gets it's power from the alternator. You need a good stator and rotor. Yours has been damaged at some time.
The pickup coils on the other side only make and break and time the sparks.

@Getafix
What you're trying to do is called a "total loss ignition system". And I share your expectation that it should work on the GS500 - provided that the battery can cope with the additional load of the starter. Most total loss systems are either bump started or use an external battery for the starter, e.g. racing bikes.
Have you tried temporarily disconnecting the headlight? The battery is fully charged, isn't it?

Here is a good description of a total loss system: https://www.russianiron.com/Total%20Loss-750cc.htm

Quote from: Joolstacho on July 21, 2020, 05:18:06 PM
The ignition simply gets it's power from the alternator. You need a good stator and rotor. Yours has been damaged at some time.
The pickup coils on the other side only make and break and time the sparks.

I don't get because it I could bump start the bike without the magnet in place and the bike was running just fine with charged battery, but without stator coils it won't start. All 3 wires coming out of the stator coils goes to the rectifier as  input AC voltage ( that are all the wires coming out of the generator system, no signal wire or anything ), the rectifier outputs on 2 pin connector which is probably DC- and DC+. From the wiring diagram i could say that the signal generator from the other side of the engine is supplying the ECU which then sends signal to the ignition coils.

Quote from: SK Racing on July 21, 2020, 11:20:45 PM
@Getafix
What you're trying to do is called a "total loss ignition system". And I share your expectation that it should work on the GS500 - provided that the battery can cope with the additional load of the starter. Most total loss systems are either bump started or use an external battery for the starter, e.g. racing bikes.
Have you tried temporarily disconnecting the headlight? The battery is fully charged, isn't it?

Here is a good description of a total loss system: https://www.russianiron.com/Total%20Loss-750cc.htm

Yes, the battery is fully charged. No headlights, I used to disconnect the headlights while i ride at day. The bike was going fine while the new magnet arrived.

Quote from: Getafix on July 22, 2020, 12:35:24 AM
I don't get because it I could bump start the bike without the magnet in place and the bike was running just fine with charged battery, but without stator coils it won't start. All 3 wires coming out of the stator coils goes to the rectifier as  input AC voltage ( that are all the wires coming out of the generator system, no signal wire or anything ), the rectifier outputs on 2 pin connector which is probably DC- and DC+. From the wiring diagram i could say that the signal generator from the other side of the engine is supplying the ECU which then sends signal to the ignition coils.

It doesn't make sense to me either. You're correct in thinking that the rectifier/regulator receives AC from the stator and converts it into 12V DC (nominal). It has nothing to do with the ignition system. So, the bike should start without the stator. As a test, you could connect 3 resistors of about 0.5 Ohm in STAR configuration to replace the stator and try starting the bike, but I doubt that it will make a difference.
Btw, the GS500 doesn't have an ECU. It has an electronic ignition system.

Stator hitting the rotor was in the hey day (somewhere around 2005-07) of this site called Goat's Syndrome. No didn't have anything to do with a real goat unfortunately.

Cos a user called goat was the first one to get it.

Lots of us have had it happen. Including me.

You have a bend in the alternator cover and it can happen repeatedly. You need to replace the rotor and the stator and make sure the cover isn't bent.
Others have also had it happen when their starter clutch goes bad and that clunk noise makes enough vibration to break stuff in there.

Whatever its cause is, you ahve to find it and eliminate it, as well as flush all that crap out of the oil pan.

Cool.
Buddha.

Try disconnecting the output side of the reg/rect to see if that fixes the no-start issue. On a total-loss system you'd have no charging circuit at all. I don't have an internal schematic of the GS reg/rect but suffice to say there's a fair chance that it puts a load on the batt when it's connected sufficient to knock the voltage down enough to prevent good ignition if there is no AC voltage on the inlet side.

Quote from: The Buddha on July 22, 2020, 05:02:21 AM
Stator hitting the rotor was in the hey day (somewhere around 2005-07) of this site called Goat's Syndrome. No didn't have anything to do with a real goat unfortunately.

Cos a user called goat was the first one to get it.

Lots of us have had it happen. Including me.

You have a bend in the alternator cover and it can happen repeatedly. You need to replace the rotor and the stator and make sure the cover isn't bent.
Others have also had it happen when their starter clutch goes bad and that clunk noise makes enough vibration to break stuff in there.

Whatever its cause is, you ahve to find it and eliminate it, as well as flush all that crap out of the oil pan.

Cool.
Buddha.

It's true, the cover is bent. I've already cleaned the oil pan, changed oil and filter when the new magnet arrived. Has't been 1k km since than. Got the stator coils on the way but it will take month or two till they arrive. The alternator cover would take much less probably, since I'm ordering from UK. I'll need some solution to ride my bike till the parts arrive

Quote from: mr72 on July 22, 2020, 05:15:40 AM
Try disconnecting the output side of the reg/rect to see if that fixes the no-start issue. On a total-loss system you'd have no charging circuit at all. I don't have an internal schematic of the GS reg/rect but suffice to say there's a fair chance that it puts a load on the batt when it's connected sufficient to knock the voltage down enough to prevent good ignition if there is no AC voltage on the inlet side.

Tried, no luck

Total loss isn't a useable solution IMHO. On battery alone without any lights you may manage 15 miles on 1 start. So a simple way to temporarily do total loss is to disconnect all the lights (headlight, dash, tail/brake all are easy to do) and just run it without the stator/rotor. Keep it on a charger when not riding.
Remember 15 miles on a full charge on a good battery, you wont even be able to push start if its dead cos nothing coming in from the stator to keep spark alive. Race bikes are often setup with a skeleton charge system where its only got like 1/3rd the coil poles on the stator. Not true total loss. So it will need a tiny tiny battery and needs to be started with an external starter but once started it will run till its out of gas. That's too much work for a temporary bike you just want to test ride etc.

Cool.
Buddha.

Been left without juice in the battery so i know how it feels  revs drops down and goes up every second even with a steady opened throttle, up until the voltage drops so much that the engine stops running completely.

Good thing is I'm working as UPS technician so batteries are not problem I got 2 12v 9ah hooked in parallel which fit perfectly. I've been riding like that without the magneto for a while now, mostly commuting to work and sometimes even riding the twisties or doing short trips near the city in the daytime. I just cant manage to start the bike since i removed the stator. The start button does noting, I've checked if the bike is in neutral, the sidestand is up and the clutch is in but it wont crank the engine. Shortening the two contacts on the starter relay cranks the engine but no sign that the bike is trying to start whatsoever

UPDATE: The problem was loose negative connection which was causing the starter relay and ignition control unit to malfunction