Bike wont start.

Oldfartaussie

Oldfartaussie

XS650 Addict
XS650.com Supporter
Messages
250
Reaction score
858
Points
93
Location
Brisbane, Australia
G'day all, my 78 special with vm34 carbs and xs1 exhaust system will not start and does not fire at all or have any response. I ride the bike everyday to work and back and it runs great. Two weeks ago one morning it was only running on one cylinder. I found left plug would not spark so I replaced both plugs and it ran great. Last week on the way home it backfired then ran very rough and sluggish but I made it home. Checked plugs and carbys , points, cam chain, tappets all good. Removed alternator case and found the alternator rotor had come apart!!. The front face of the rotor with the slip rings which is secured with six screws underneath black plastic caps had all come loose and spinning around inside the stator smashing of the brushes and the brush holder. I have installed new rotor, brushes and holder, all replaced at no cost from Geoffs xs as it was less than one year since I bought the rotor and a solid state reg/rectifier because I had charging trouble. I now have no power at either brush, fails slap test but would that stop the engine from starting. Any ideas would be greatly appreciated
 
On a '78 charging system, the regulator supplies power to the alternator rotor. If the rotor became shorted to ground during its decimation, the solid state regulator's driver could've been cooked, or its power wiring could be toasted. Normally, the fuse would blow before all that. Time to get the '78 schematic and a test meter...
 
Thanks for the reply Twomany, I figured the reg/rectifier is fried, not sure why it didn't blow the fuse. Will see if Geoffs xs will replace it as it was the faulty rotor that caused it or its $165aus for new solid state reg/rectifier unit, and $295 for a stator. The new rotor reads 5.2 on the slip rings and I get no reading with one wire to slip and one to engine?. No power on the green to outer brush. 4.6 ohms on the three white to stator. Can't see why it won't start though, I even replaced the fuel and plugs but it is dead like its shorted. Will get the reg unit and keep trying but happy to hear ideas.
 
Check the brown wire on the ignition coils for voltage.
Disconnect the regulator and try and start it .

Green wire on brushes I think should be grounded.
 
Thanks Team junk, that's a good idea I'll try starting with reg unplugged. The green wire goes to the outer brush ungrounded and black to inner brush which is grounded to stator frame. Will check coil volts. Hope they are not fried, but I am getting plenty of spark. Appreciate all the help.
 
Ok, disconnected the reg/rectifier like team junk suggested and it sounded like it was going to start, but it was late so left it thinking I had made some headway and i would start it up next day. No such luck, it will not fire at all. Checked compression,138 left, 145 right. No fuses blown. 12.5 volts at coils. Spark at plugs but not the brightest I've seen. New solid state reg/rect is on its way. Drilled hole in stator face for the newer type brush holder to seat. 12.65 volts at battery. Red wire at switch 12.65. Brown wire at switch 11.95. Red to rectifier 12.65. Stator has 3 white, green, black and sky blue at 6pin connector none of which have power.?.rectifier 5 pin connector has 3 white, black, and the live red. The 3pin regulator connector has brown, red, green. The new solid state reg/rectifier has seven wires, red, 3white a green, brown and a black . Any advice is welcome, and appreciated.
 
Hi
Since the problem was loose parts in the rotor region this now replaced ..and up to standard
New rectifier coming in
I would check the stator before connecting anything else.
And then check the ground connections.
 
Thanks jp, curlys white wire to white wire test at stator side of 6 pin, all three .9 ohms.?? No change with yellow unplugged. White to battery negative 2 wires 32ohms, 1 wire 20 ohms.? White to frame or engine i get no reading.? Haven't found an earth strap other than the battery negative. Still trying to figure out why it won't fire.
 

Attachments

  • alternator rotor.jpg
    alternator rotor.jpg
    231.8 KB · Views: 134
  • alternator rotor.jpg
    alternator rotor.jpg
    209.8 KB · Views: 124
If the stator is OK ( have not checked values but the test method is out there )
Rotor is OK
New rectifier incoming
And now
Spark at plugs but not the brightest I've seen.
That is still possibly a bad Ground ...

Something like that

Points.JPG


Contact breakers and Condenser ground needs to be connected to Battery frame Ground.
Grinding those frame connections clean with Carborundum paper and applying contact grease.
Or draw a separate wire to battery minus for fault finding.
Bad ground has been a common problem on close to ten bikes last 6 - 8 months
So that would be a first in my view.
 
Ok, bare metal under earth strap on top engine mount and earth to coil bracket. Earth strap from reg/rectifier mount bolt to negative battery terminal and earth wire from reg/rectifier to frame. Brown wire at regulator 11.95 volts. No power at brushes and still won't ,fire/start!!?? No melted wires anywhere and no fuses blown. All ideas will be tried and appreciated.
 
There are different types off Regulators pre 80 and past 80 depending a little on market
Please check that it is the right one perhaps a picture and a description and work on until you have power to the Brushes
aka check connections .once more
11.95 is on the low side ..please check what it is on battery
Any sparks ?
 
Solid state reg/rectifier sold by Geoffs xs to replace separate regulator/rectifier for 1970 to 1979 models. Looks the same to me as the one for sale at Mike's xs. 12.65 at battery. 12.65 at red wire at main switch. 11.95 at brown wire at main switch.? Still have some hair left so I will keep chasing wires.
rectifier.jpg
 
Is your bike an Australian original, or US import............Big difference when listening to advice.

Aussie, (Oceania), XS650S /are/had points only models from 70 till 81. 81 was the last Oceania model.

An alternative to buying an aftermarket SS Reg/Rect is to buy a Bosch regulator, (cheapest alternative here in Aus.
https://www.ebay.com.au/sch/i.html?...fLoc=1&_osacat=0&_odkw=bosh+voltage+regulator

And buy a 3 phase Rectifier, or 2 single ones and wire them in line to crate a 3 phase rectifier. Need to do some minor wiring but way more reliable and Cheaper that buying from GeofsXS.
https://www.ebay.com/sch/i.html?_fr...osacat=0&_odkw=3+phase+25amp+bridge+rectifier
 
Oldfartaussie said:
Solid state reg/rectifier sold by Geoffs xs to replace separate regulator/rectifier for 1970 to 1979 models. Looks the same to me as the one for sale at Mike's xs. 12.65 at battery. 12.65 at red wire at main switch. 11.95 at brown wire at main switch.? Still have some hair left so I will keep chasing wires.View attachment 189654
Click to expand...

Yes that looks to be the right SS Reg/Rect for points models...................GeofsXS, MikesXS and 650Direct sell mostly all the same products
 
Bit Busy now
So if the right regulator the main focus would be to figure out why not any power at brushes
Perhaps remove other fuses except main and and follow the voltage downstream on the charging circuit.
I am out at the yard now but later to night There will be more time
Please give the Right model no and or the right Schematic.

Fault finding manuals can be found there

https://thexscafedotcom.wordpress.com/2011/01/10/xs650-manuals/

Perhaps that please check

https://www.xs650.de/literatur/wsh/pdf/06-elektrik.pdf
 
Thanks for the info 650Skull, Geoffs replaced them but if I ever need a reg/rectifier I'll get the bosch and a 3phase. Not sure if its an import or not, I'm the 3rd owner but going by the engine and matching frame numbers it is a dec 78 SF special with a 4 wire main switch and safety relays removed by po's. No wiring diagram came with re/rectifier so I searched it and mikes xs looks the same but confusing wiring advice says whites to yellow, orange to such and so on. As visible in photo unit has no orange or yellow so not sure i have it correct. Will keep checking for power loss wires and fault finding after work Jan p.
 
I'll make a suggestion here if I may...
Charging and ignition are two different systems. If it were me, I'd ignore the charging system issues for now and worry about getting spark to the plugs. Once you get it running, you can worry about charging. Reading above is just confusing because the idea is to get the bike running and all the talk is about regulators, rotors, stators, brushes and such.... none of which have anything to do with making the bike actually run.
So my suggestion... let's concentrate on ignition. I believe I read above that you have power to the coils, correct? If so, take the lead coming out of the coil and going to the points/condensor.... disconnect it and touch it to ground... then remove it from ground. Kinda like tapping it to ground. Grounding it charges the coil. As soon as you un-ground it, the coil should fire the plug. Tap it a half dozen times or so and see if the plug consistently fires. Does it? If it does, that's a good coil, ht lead and plug... and we're getting good power to the coil. Answers a lot of questions no? Let us know and we'll press on from there.
 
Thanks Jim will try that tonight when I get home from work. Just to recap bike ran great, alternator self destructed and since then bike will not start. Happy to receive and try any and all tips.
 
Oldfartaussie said:
Just to recap bike ran great, alternator self destructed and since then bike will not start. Happy to receive and try any and all tips.
Click to expand...
The alternator destructing and the bike quitting are actually two different issues. It's likely they both have a common cause between them, but troubleshooting an alternator issue on a bike that doesn't run is damn near impossible as the engine needs to run for the alternator to work. It'd be much easier to find out why the bike won't run.... and in doing so, we'll probably discover what's wrong with the alternator. Sorry if I sounded gruff... wasn't my intent.
 
No problem at all Jim happy to have you on board and sorry for any confusion to all readers but my main objective is to get the engine going and totally agree ther must be a common cause as I have spark at plugs and fuel in carbs and it always started 1st touch of the starter every morning but now it does not fire at all and I have the cover off to see the points fire. Will try grounding the coils tonight. Hope it tells me something.
 

Similar threads

JNaw
Rotor melted itself 500km after rewind?
Replies
15
Views
325
JNaw
JNaw
Fingerscrossed
In neutral: kickstart won't move, elec start won't engage
Replies
5
Views
259
gggGary
gggGary
I
Pre recommissioning electrical checks?
Replies
13
Views
422
Its been a long time
I
E
Question about rotor and charging.
2 3
Replies
41
Views
2K
Eric12171
E
Crashedkiwi
Dazed & a bit confused
2
Replies
33
Views
1K
Crashedkiwi
Crashedkiwi
Back
Top