stumped on 71 - no spark

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bigjake

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Hello. This is my first post. I could use some help...

I just bought two xs650s off of a guy, one runs (72) and the other (71) sat for 25 years not running and it has me stumped.

I started troubleshooting - using a good shop battery - and discovered the key switch was working on position I, but not II. I cut the switch out and tied the red and blue wires together to get power to the handle switch. However, the handle switch was missing the run/kill slide lever, so I bypassed the switch and twisted the red-yellow with blue, and added green and yellow wires (to test the headlight - it works).

Next I tried to kick it over with a screwdriver in the plug wire next to the block and no spark, so I tested continuity on the coils and I got a reading between the red and brown leads on each. Next, I cleaned the points and ohm-tested the rotor. It read 0 ohms from inner to outer, which seems wrong. Rotor and stator look old and dirty, but no obvious damage.

Still no spark. Where should I go from here? Did I miss a step, or wire something wrong when bypassing my bad switches?

Appreciate any help.
 
Hi jake and welcome,
try bypassing the lot and hooking the coils directly to the battery.
And yes, zero resistance shows the rotor is shorted out.
A good rotor should read between 4 and 5 Ohms so if you have your meter set to one of it's higher ranges or if it's an el-cheapo meter that only has a MegaOhm setting it won't see a difference between 5 Ohms and zero Ohms.
 
Thanks Fredintoon. I did have the ohm meter too high. It's reading 5.1. Can you elaborate on how to hook up the coils to the battery? There's a red and brown lead coming from each and don't know what to hook up to positive/ground. Also, once they're hooked up, how would I test?
 
welcome jake :thumbsup:
this video might help . Its basic but it explains how the charging system works and how to test the rotor with a multimeter.
I would suggest you remove the electrical connector to the stator and the brush connector block if the rotor is still on the bike.

Basically you need 12v+ going to the outer ring on the rotor and the inner ring on the rotor should connect to ground (chassis) .
When you have 12v+ and 0v connected to the rotor you should get a magnetic field in the rotor windings.


When you switch your ignition on you should get a direct 12v+ going to both of your coils from the battery .
If you do not have 12v+ at the coils and you are going to try connect 12v+ to your coils directly with a wire from a battery I would suggest that you remove the original red and brown wires on the coils first,.... in case there is a short in your wiring loom or something hasn't been connected correctly.
 
BigJake: If you are easily angered, ignore this post and carry on.

Basic suggestion: One thing at a time, troubleshoot/repair the ignition circuit, then move on to the charging system.

Read up on setting points, it's a fine, near forgotten art. Old worn out points are difficult and sometimes impossible to set. The condensers are often/usually bad. The stock coils were just OK when new, 40 years has taken a toll on every electrical component and connection. Grounds matter as much as the +12 volt side of the circuit.

Cut and twist wiring just scares me. Shortcuts and a lack of understanding of design component function while electrical trouble shooting will bite you in the ass every time.
The key switch positions are Off - On - Park, the last position is for parking, tail ight only, yes that is silly)

Slow down, fix each item THEN move on.

Are you aware of the value of stock early bikes? There is a ratty no title 71 on sleasebay right now bid to $1800 with a few hours to go!
Just say'n you reduce the market value of your bike with each clip and twist.

OKAY I'm off my high horse. Please keep talking with us and post up some pics? We LOVE pics!
 
Last edited:
Thanks peanut, I'll give that a try.

gggGary, appreciate the note. It is actually bone stock, but I want to focus on getting it running before deciding what to do with it. I can appreciate the scariness of cutting and twisting wires, but I'm not going for a restoration and I don't have much into it yet... I've got to learn how the system works somehow and the diagrams and youtube have only gotten me so far In understanding each piece of the system.

Now the nugget of information you've shared about the key positions really makes better sense of the wiring diagram to me... no wonder I was confused. I'll check rotor, coils, points and test or replace condensers.

What's not clear yet is where the line between the charging system and ignition system is, but I think your insights about the key position will help with that.

I still appreciate your help and insights. Thinking my goal for this bike should just be to get it running, learning what I can, and sell it to make room in my garage for doing a cafe job on my 72, which has front disc brakes and already runs... might keep me married too.
 
Hey, bigjake, welcome to the forum. Would like to see pics of your '71.

Felt a disturbance in the force earlier today. Now I know why. I think that gggGary was gritting his teeth hard enuff to enduce a space-time causality warp. (Nicefication???) Probably others too.

Kinda like hearing about a fellow who found a Stradivarius violin in his grampa's attic, and uses it to crack walnuts.

Take yer time. Try to avoid cutting wires and such. We have plenty of info on this forum to cover many of your resurrection attempts. Or another option, your '71 can easily find a new home.

Here's a '71 schematic.
 

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Thanks TwoManyXS1Bs. That's a good schematic. I have determined my rotor tested out fine and is getting power. Need to test coils and set points still.

Sorry I'm not a purist... I knew where Gary was coming from. I just prefer custom bobbers and Cafe bikes. However, the stock '71 isn't what I have my eye on for butchering (completely). I just want to get it running, make room in my garage, get my money back out of it and put that money into doing the custom build on my '72. It runs, but was assembled from parts from various year XS650s - perfect for cutting up. I respect the guys who are into restoration bikes, and maybe there's someone who will think it is a good deal - minus a couple of temporarily bypassed bad switches... or recently replaced ones.
 
BigJake,

I think you I should save you the frustration and heart ache of trying to get that one running.

I'm a purist and lover of these early XS's and I'd gladly take that one off your hands for you to keep your wife happy and keep gggGary from having just one more too many XS's in his stable!

Seriously...
Vincent
 
The only place the charging system and ignition come together is they both hook to the battery. The charging system does just that it charges the battery. The ignition draws a bit of power from the battery to get the plugs to spark.
Do you have a repair manual. The Clymer is ok, the Haynes is ok, I like the Yamaha shop manuals. I got most from Ebay, 70-80 paper books. The 81 up as downloads.
By reading the books you will better understand how each system works and how they relate.
Leo
 
Vincenthdfan, based on your profile, looks like you and gggGary are competing for who can own more early bikes...

Thanks XSLeo. I have the Clymer, which seems just okay. The responses in this thread have been a huge help in understanding how the system works, and how to troubleshoot. Looks like it's a right side coil issue. I couldn't find condensers. Is it possible the early bikes didn't have them?

Jake
 
Hi Jake,
perhaps you meant capacitors? My bike has the later iggy which don't have them but I remember a post that showed that the capacitors are hidden on the frame someplace.
Follow the wires back till you find them.
 
Points "always" have condensers. Look at the connector in the wire from the points to the coil it has 3 wires, one to the points, one to the coil, one to the condenser. there are 2 condensers together in one housing it is bolted to the inside of the left hand top engine mount.

You can see it in the middle of this photo.

$_57.jpg


You can see the connectors and leads to the condensers (AKA capacitors) in this 5twins pic.

CondenserHook-up2.jpg
 
Yes, the condenser "pack" is pretty much buried on the backside of that engine mount. Here's a bit better pic. You can see it hanging out below the mount a little bit .....

CondenserHook-up.jpg


I would suggest getting some new points. You're going to need and want them anyway for the '72. Try them out on the '71 first to see if the ones on there are the problem. As mentioned, they can look good but be bad, and there's no telling how old or how many miles are on the points in there.

You can try a static timing check to test the points you have now. Hook up a little 12v bulb to one set, then the other. With the key on, rotate the motor with a wrench on the rotor nut. If timed right and with functioning points, the light should come on when you get the rotor mark around the "F" mark on the alternator. That indicates the points have just opened. An inch or so past that, the light should go out again when the points close. Keep rotating the engine around and the light should come on again when you reach the "F" mark again.
 
Indeed. You guys talked me out of butchering it... for now. Reserve not met, so I guess it's still a possibility. The (non-original) '72 is going under the cutting wheel as soon as the '71 moves on to a 'nicer' home.

Thanks again for everyone's help. I'm sure I'll ask more dumb questions when I dig into the '72.
 

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