I thought I was an ok mechanic untill.....

Uggh. Groan....

:lol:

 

Did I ruin your day?

 

Haha. No, my friend. Not a chance.

I'm thinking that since it's raining buckets here anyway, I may grab a scope and wander out to the garage and see what I can see.

Would be nice to have some pics for the no-spark discussion....

 

No, but Tiny's bike still won't run. The only thing running is us running out of ideas.

 

I have scoped the pickups, and any bias is probably nothing more than unintentional DC offset from the TCI box. The signal is very AC and gets up to an easy 80V p-p at higher RPM's. You should be able to read the signal much better on AC even with an analog meter.

Cheers,
Paul

 

Suppose the resistance of his pick-ups is bad (out of spec)?

Like way out of spec? Like if the pickups are out of the wrong model year bike, which are specified at 120 ohms, and his pickups are supposed to be 700 ohms (or vice-versa)?

What goes ka-blooey then............?

 

Cool. Thanks for the details.

Wow. That 80p-p is a little scary... I don't know about the 650 TCI box, but on my 550, the first thing they do with the signal off the pickups is to hang a .047UF 50V film cap to ground.

Seems at +/- 40V they're running closer to that 50V rated voltage than I would have been comfortable with. Call me conservative? :wink:

 

Its over 20% which is a standard guardband limit but I like 50% or more on caps. Interesting maybe the 650 differs - larger pickups so higher peaks?

 

Haha. Yeah, granted that most of this banter isn't getting him any closer to getting his bike to run, but it's not like we're out of ideas yet!

We've still got two big cards yet to play... The coils, and the TCI itself, right? :wink:

If he's got:

1) ground where and when he should have ground
2) power where and when he should have power
3) pickups that are functioning properly
4) a TCI that is functioning properly
5) coils that are functioning properly
6) plugs that are functioning properly

and after all of that he still doesn't have spark... THEN I think we're out of ideas!! 8O

 

Yeah, exactly. My margin of safety is more like yours. Especially with something of this expected longevity and rated operating temperature range...

I don't know if the 650 is the same or not. My only hard experience is with the 550 as that's the only thing I have here. I don't know why the 650 would have to be any different. I'm not sure larger pickups buys you anything. It's not like they need to be sized to the cc of the motor or anything... :?

Just looking at the big picture circuit diagram of the 650 it's clear that all the concepts are identical with the only difference being the inclusion of the side stand safety interlock on the 550. I don't know if they have the exact same component hanging off the pickup in there though.

Burnarr

 

If you're running out of ideas then we must be narrowing it down. I'll go measure the changes in voltage on the coils in a/c and d/c and post my results tonight. I'll double check the coils and post those results but I know they're good. I'm still going through the wiring with a diagram and ohm meter making sure everything is how it should be but between work and not having light to work on it at night it's going slow. Can anyone tell me what runs through the diode pack? I appreciate all your guys help and know that if I can keeep my cool we will get this bike on the road.

 

Tiny, the diode pack is used for turning on the oil indicator when the starter button is pressed and for energizing the headlight relay when the engine finally starts. (I hope soon)

 

Wow. I've got to say I am impressed with this thread. Sorry, Tiny, I don't know much about the electrical components of these bikes, so I can't help you. But let me just say that this thread exemplifies what this site is all about...people helping people. There are guys on here who genuinely want to help. You can feel their passion for wanting this bike to run. You'll get it going, Tiny. There's no doubt in my mind. You've got an army of XJers behind you.
Thanks to all of you XJ masters out there. I feel better knowing that when I encounter a problem I can look to you guys for help.

 

I'll be doing tests here and there as I have time. But my work on bike time has been reduced drastically as I have a friend whos moving and when she gave me the puppy dog face I caved and offered to help. There goes the weekend. It kills me to not have time to work on it when we're so close. I suppose the next logical step would be testing the tci on a bike that we know runs good. On the bright side if we can't figure it out by the fourth of july it's gonna make a hell of a firework :twisted:

 

do you have a relay right under your tci box? If so make sure you are plugging the right connecter into the tci. I put the wrong plug into the tci box and fried 2 of them b4 i realized i was using the wrong plug I was plugging in the headlight relay into the tci thus sending power into the wrong places

 

*UPDATE* I noticed that the bike still turns over if its not in neutral. Any ideas?

 

Nuetral safety switch is not working.
Check THIS thread and the Haynes manual for some help

 

I know the switch isn't working. My question is could this be why my bike wont start? I don't care that the switch isn't working I just wanna hear my bike fire.

 

if i read that link correctly, the neutral switch would keep the starter from turning over.

i believe the case here is that the bike turns over, just no spark.

have you tried brand new plugs yet? this spring i had 2 plugs that didn't look that fouled, but wouldn't spark. replaced the plugs and voila! spark.

the spark is pretty weak until the engine revs up a bit. (granted, i may need to replace my starter brushes as well . . .)

edit: nevermind - if new plugs would solve your problem, you would've got jolted when you stuck your finger in the wire.

 

According to the wiring diagram posted earlier, if the engine is spinning, there should be spark.

No relays, no interlocks, no safety, no diodes, no nothing...

You spin? You spark.

 

Can we get a confirmation that this is the correct wiring diagram for the bike in question?



I know it's a long shot, but... What if?

 

I grabbed that clip from the Yamaha XJ650G service manual.

My bike is an XJ650H and it's a 1981 model. The G model is 1980, which I believe is what Tiny has.

 

The 80 model only has starter lock out - no TCI grounding according to the haynes manual

 

Another note:

The diagram I posted is the simplified version just showing the ignition circuit. There is also a complete wiring diagram that shows all the plugs and connectors which can be found in the Haynes manual and the factory service manual. He would definitely need that if he is going trace every wire in the harness.

I hope when he finds the fix he posts it - I would love to know how this turns out.

 

Gitbox, do you think I would drag you guys through this and not post the answer when I find it? Of course you guys will be the first to know. Well the second, my buddy that thinks I should sell it and get a "good" bike will be the first to know.

 

Get GRANULAR here. Get downright freaking molecular.

This is an INANIMATE OBJECT built of wires and plastic and metal and rubber; it was created by human beings.

WE are human beings (ok, mostly, sorry) and therefore MASTERS of this damn object.

MASTER it already, willya? This is exasperating...

Seriously; this IS a "good" bike, as soon as it runs. You cannot let it win.

 

since the suspense has been killing me - i collected all the information from tiny's posts and summarized them here.

this may not be everything that's been checked, but i don't see a kill switch check in there. anyhow, in the interest of not having to comb through 9 pages of thread to see what's been checked and what hasn't . . . please say you haven't checked the kill switch, please say you haven't checked the kill switch, please say you haven't checked the kill switch.

 

The kill switch must be OK or the bike wouldn't crank at all. Also, there wouldn't be power to R/W wire at the TCI.

I'm putting my money on the TCI. I don't like the looks of this:

"ignitor unit drops from 12.8V to 12.2V when engine is cranking"

Well, that and the part about it sparking when it hit the frame... :lol:

Nice summary Skeeter.

Burnarr

 

oh - my bike will crank with the kill switch off (just no spark) - although i don't think the wiring is "stock" either.

 

My 81 max does not do anythng if the kill switch is set to stop. My 82 will spin, but no spark.

 

Lets just assume for a moment i haven't checked the kill switch. How might one go about doing that? If it is the kill switch I will feel like a moron since wamaxim suggested that almost two weeks ago. But I was told if it was the kill switch it wouldn't crank at all and after reading what skeeter said it couldn't hurt to check. Thanks for the summary skeeter. I have another tci box that to the best of my knowledge is good. If I don't figure this out soon I will send all my tci units out to robert for a check.

 

i don't know too much about ignition circuits but to check your switch i would just open the cluster on the handle bar and find the two wires connected to it (they might even be the same color). check the resistance accross the switch, then toggle the switch and check it again. should read 0 ohms one way and open-circuit the other way. i *think* the kill switch is supposed to ground something in the ignition circuit to prevent spark - but i could be wrong. if i'm right, then i'd guess you should read 0 ohms across the switch when it is in the "off" postion. not that it really matters. i think as long as you see a change in resistance across the switch when you toggle it you'll know if it's working or not.

and as far as wiring not being "stock" - my bike will crank over with the kill switch off *and* the key turned off. i've had more pressing issues, but do plan to sort the wiring out at some point. i think it has something to do with that exra wire connected to the battery. course, now i'm wondering if my starter solenoid has been bypassed. aye-carumba. good thing i've never had to crank it for more than half a second.

edit: i'm gonna go out on a limb here (someone PLEASE chime in if i'm wrong - we don't need to send anyone down any rabbit holes). but i think if it appears your switch is working properly - the circuit might still be bad. if you can get 0 ohms across the switch, turn the key on and you should see 12V on one side and have a good path to ground on the other.

 

Follow the link I posted on the last page, #6 is testing the killswitch.

 

Unless Haynes is wrong, or your harness has been reengineered, you shouldn't need to test the kill switch. You told us that you did have solid 12V to the coils and to the TCI. The kill swith on your bike, according to the Haynes schematic, cuts out that 12V and, again according to that schematic, also cuts out 12V to the relay that feeds the starter solenoid.

I guess one thing you could check is to set the Run switch to Off and then see if the starter cranks. On your bike it should not.

 

You need to test the Kill Switch... It will allow the cranking of the motor but suppresses the spark (I got my bike cheap because of this).

 

Simplest way to test the kill switch... when you turn it on and off, you should hear a faint relay click. All 3 of my XJs do this.

 

Yes, but yours is an '81 H, not an '80 G. On the G, the kill switch turns off 12V to all R/W wiring: starter solenoid, TCI, coils, etc.

 

"Simplest way to test the kill switch... when you turn it on and off, you should hear a faint relay click. All 3 of my XJs do this."
I hear a faint click. We're good. My ohm meter is toast so I can't do much until I can get a new one

 

So i noticed something wierd retesting my wires. Three of the plug boots have resistence and one has almost none. Should I have resistence?

 

Yes. All the boots should be about 5K Ohms.

Although I don't think this would be your main problem.

 

Alright I'm back. I haven't touch the bike since june. I haven't ridden anything. There has been no motorcycle related thoughts in my head. Untill....
Yes I did it, I looked under the tarp and saw my bike there. Now I'm going to be going threw it from the spark plugs out. Hopefully testing the components I have to make on a good running bike to make sure they are good before I replace them. But I will replace whatever is required. Once I get spark I'll rebuild the carbs, then all the maintenance issues that pop up on these olds yamahas. I had almost had my xs done when I decided to take a little break from bikes and will probably have that on the road with a little luck (waiting for a gas tank to pop up). So there you have it, I'm back and ready to kick this bikes ass. I need to thank you all for your patience and can't wait to get this thing done.

 

Quick question for the gurus. If one spark plug is not grounded will the other plug on that coil still fire? I know it seems like a dumb question but I remember working on an old chevy that was like that.

 

With waste spark coils - coils that connect to two plugs - both plugs will fire at the same time. One will be igniting on the compression stroke, the other will be sparking harmlessly on the exhaust stoke. If one plug isn't connected, the other on the coil won't work. They form a circuit, you see.

Your problem sounds like pickups or wiring.
Make sure the gap between the reluctor and the pickup is at spec... I don't know what it is, but there's a spec out there.
Testing a magnetic pickup is pretty easy. Connect something that'll give you 'movement', be it an analog needle sweep, or a bar graph on a DMM, or a waveform on an oscilloscope...
Again, I am not sure what the spec is, but there should be an equal amount of 'movement' on both pickups.

For wiring, tear out every wire and connector, and closely examine them all. Replace every wire and connector if you have to. I'm thinking about doing it on my bike - replace those corroded bullet-style connectors with something a little more weather resistant.

 

Bobcharles, you've got it. I plan to make a whole new harness if I have to.