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Discussion Starter · #1 · (Edited)
So I've started a few threads about this but I wanted to bring it all home, since I've found out a lot since starting this process. A little background, I picked up this bike for $150. In general the bike structurally seemed to be pretty sound. But it definitely was a basket case with issues. I found out I had poor compression in 3 or 4 cylinders and that there was no spark to boot! Before I decide to dive in and put new rings in I wanted to confirm that I could get spark. I have never seen this thing run.

Hope y'all aren't getting tired of this, but I have greatly appreciated the help, and one of the things I'm finding frustrating on other forums is that once the problem is solved, no one checks back in. So here are things I've found out since this discussion as taken place. And I can say that this is true for a '99 YZF R6. Also I want to clear up some of the language we have used to make sure that also does not get confusing:

The charging assembly essentially has nothing to do with spark in the case of my bike. We have discussed the stator which produces AC voltage that then goes into the regulator/rectifier which essentially converts AC voltage to 12V DC voltage that won't fry the battery when charging it among some other things as well. These parts are not necessary to create spark. In-fact I did hear of a lot of people that take them out to reduce weight in their bike for racing. Granted, they must recharge their battery by other means more frequently.

Taking these things out of the equation, if I go to the repair manual, with a spark issue or ignition issue it lists none of those charging components as needing to be checked, further confirming they do not tie in - for now. Based on what the book says I have checked the main fuse and the ignition fuse to make sure they weren't blown, I've bought a brand new battery and it tests out good as well. I have brand new spark plugs, although they were probably fine before. I have tested the ignition coil resistance (primary [0.204-0.276 ohms] and secondary [8.5-11.5 k ohms] - all checks out), I have checked the pickup coil resistance which is pretty easy, it read about 286 ohms (spec is between 248-372 ohms). (Sidenote: testing ohms under 1 ohm is a giant PITA, because most ordinary multimeters do not read accurately that low, so for instance on primary resistance for my ignition coil packs the ohms were so low, the best my meter would read was .3 however it was .3 for ALL OF THEM, and I doubt all went bad and my multimeter was incapable of reading anything more specific - this was also the case with the stator resistances where I believe they needed to be around .25 to .33 and it read .4, again doesn't matter for what I'm trying to do here since I'm not yet worried about charging, but still I think its probably fine). BTW, none of this do you have to take off the components to test them, just find the end of the first connection loom. I have checked the continuity of the main switch, engine stop switch, neutral switch, sidestand switch, and clutch switch.

Second to last thing before I conclude that my ignition control unit is bad is to check the SCCR (starting circuit cutoff relay) ignition circuit diode. It instructs to connect an ohmmeter postive test lead to sky blue terminal and to connect negative test lead to relay's blue/yellow terminal and the diode should have no continuity in this direction (for me that checked out), next you reverse the leads and you should have continuity. Well of course this is where I ran into a problem - first off, my continuity tester in this position did not make the continuity beep sound (which I would guess means, hey, this relay is bad) - however while not making the beep sound I saw that the display read like 627.... not sure what that meant.

At this point in time I'm looking into what a new SCCR may cost. Also confirming that my test was accurate. I'm really hoping this may be the culprit. I'll check back in if and when I find out more.
 

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Mr. HER6
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That sucks that you don't have a better meter to use, but your reasoning about the low resistance readings is sound. I would also consider those results as likely to be good, but not with full confidence.

Your multimeter's continuity test mode is really a diode test mode. When the meter sounds the continuous beep, that means there is no (well, almost no) resistance and the display reads zero. While this is convenient for continuity checks, it doesn't work for diodes because they still have resistance. The number it displays is the diode's resistance. Your meter should have some indication of units, so I'm guessing that 627 is actually in milli-ohms. If it reads "0L" that means the circuit is open so either the diode has blown or a connection isn't being made. I don't know the spec for that particular diode, but in regulators the upper limit is usually 0.6 Ohm so you might be ok there.

Regardless of the spec, it is indicating that the diode is allowing current to flow one direction with some resistance, and no current to flow the other direction, so that's a good sign. Maybe someone here with a 1st gen bike can check theirs and tell you what the diode resistance should be. It's possible that it has degraded and the resistance is high enough to prevent it from functioning right.

Maybe I have missed it, but have you done continuity tests from the CDI box across to the coil packs? All that small gauge wire and especially the crimped connectors are potential failure points. Undo the connections and probe from the very ends on the connectors. Wiggle them around a bit too to verify that the connections aren't intermittent.
 

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Discussion Starter · #3 ·
HIS OWN 6-Nice to have you on board this topic, you seem quite knowledgeable about the ends and outs of this bike. The description you gave of how the diode works and the tester sounds spot on. I actually spoke briefly with the motorcycle shop here in town to investigate how much one of these relays cost (about $70 or so for anyone who wanted to know). When I spoke with them on the phone they essentially said the same thing you did about it probably being good. However they do have a relay tester, so I will go and get it tested tomorrow just to be sure.

With regards to checking continuity between the CDI unit and individual coil packs, I have done this. I can confidentially say that I have continuity from the orange and grey wires to coils 1-4. There are a few other wires on there I believe I tested for continuity at the very beginning. But tonight my mission is to re-check all those for continuity and recheck my grounds up by the coil packs. Once I have established these are all good I will likely plug all my spark plugs (they are new) back in and pull one out and run through the spark test one more time. If this doesn't check out I will likely start considering a new CDI unit...of which I have two conundrums with: CONUNDRUM #1) I cannot find a new one anywhere. Even if I did, sounds like they are OUTRAGEOUSLY expensive. So the other option is to try to find one used online they go for around 100-200$. Even if I do replace it, what if it doesn't fix my spark issue? I mean if it didn't I might suspect that the CDI unit I bought was bad OR I may conclude that maybe the new one I buy is good, and maybe I replaced a good one and still my problem lies somewhere else. Moving on to CONUNDRUM #2) I have cranked the engine and put a voltmeter on the loom that plugs into the coil pack (in other words the voltage should not be ramped up yet), when I do this I get a fluctuating voltage 50-100-150-200V ish and it bumps up and down, I think the reading is negative for some reason (although I don't know if this is significant). Well this seems acceptable to me, it seems as though voltage is passing through the CDI unit and on its way to the coils, where it delivers voltage in a sequence (which would make sense for alternating spark for individual cylinders). I wish it would read ZERO voltage... that would make me almost certain that the CDI unit was bad...

Here is my request, can ANYONE that has the same bike that I have check this voltage going into their ignition coil packs....and tell me if they see the same thing? There are no specs on this that I can find and its impossible for me to tell what I'm actually supposed to be seeing. I know its alot to ask but I'm right crap creek without a paddle.
 

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Mr. HER6
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Are you remembering correctly on measuring 800 Ohm on the pickup coil? I found a service manual and it says that should be 248 to 372.

I'll need more time to read through and figure out how to verify that it's not intentionally cutting out the ignition.

One thing I do notice in the wiring diagram is that the coils are paired together and they daisy chain the CDI signal across these pairs. After going through the second coil, this signal goes to ground somewhere. If you haven't already, check continuity of the line between the coil pairs (orange on one pair, and grey on the other), and also from the second coil to ground (black for both pairs). You can check this one against the chassis or negative battery terminal if you don't want to trace it. If you're measuring the signal voltage against the chassis you may see voltage, but it doesn't necessarily mean that the circuit is closing and allowing the coil to see the voltage.
 

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Discussion Starter · #5 ·
In terms of the pickup coil I'll double check the recommendation from FSM again tonight. If i recall it was higher than what you read, but just to make sure...

I have checked the daisy chain, but one thing I forgot to check was both of those grounds you pointed out. That's one of the other things I was going to check when I got off work tonight. Also good point for monitoring voltage, and having the coil not recognize it, I'll be interested to see if those grounds check out. Honestly if they do I'm about to reach the maximum puzzlement I've had in a while... This is worse than doing the headgasket/clutch on my tacoma that I had to do recently... unbelievable.

Thanks for the help so far, hope y'all can hang in there with me.
 

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Discussion Starter · #6 ·
Ok, workin on the bike now - the pickup coil resistance for the 1999-2002 models is supposed to be between 248-372 ohms at 68 deg. F. I'll edit my first post, I'm not sure what I was talking about there, but I can say that my pickup coil resistance is 286 ohms. So we are all good there. About to go check some of the other things I discussed.
 

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Mr. HER6
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Some other lines to check for continuity are

red/black from CDI to the SCCR and the handlebar kill switch
white/red from pickup coil to CDI
black/blue from pickup coil to CDI
good contact across the pickup coil harness

If that relay we talked about tests good, and all the other continuity and impedance tests check out, then I think it'll be time to try getting another CDI box.
 

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Discussion Starter · #8 ·
Some other lines to check for continuity are

red/black from CDI to the SCCR and the handlebar kill switch
white/red from pickup coil to CDI
black/blue from pickup coil to CDI
good contact across the pickup coil harness

If that relay we talked about tests good, and all the other continuity and impedance tests check out, then I think it'll be time to try getting another CDI box.
Checked the entire CDI unit for continuity to all of the respective wires that seemed important for ignition.

Red/Black = checked out, and checked the switch for continuity when on and off and it looked right

White/Red = checked out from pickup coil

Black/Blue =checked out from pickup coil

Should I be running a test lead to a ground to see if any of these are "grounded out" - feel like sometimes its hard to know whether or not they should be grounded, some seem to be obvious, others not so much.

Anyway, gonna have the relay checked tomorrow - I'm about to re plug everything in and pull plug by plug and check for spark again just in case I bumped something...

Very grateful for the help as usual - Thanks!
 

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Discussion Starter · #11 ·
Wow - ok, this has been a total battle with engine :swordfigh I can't believe it took me this long to get the spark going. So let me first say, what led up to the events briefly tonight, and then what I may do differently next time: Tonight I rechecked continuity as discussed and a bunch of other double triple checks. Then I reassembled everything for the most part. I put 4 brand new spark plugs in, the chincy brand (autolite I think). Then finally when most everything was together (I left the airbox and gas tank off) I pulled one single sparkplug/coil pack and I made an artificial ground to go the negative terminal of my battery by stripping a piece of wire, then I wrapped it around the threaded part of my spark plug to do a hands-free and certifiable ground.

I then turned off the lights switched on the key and the kill switch to the "run" position....AND BAM :cheers :flame WE GOT SPARK. AND IT WAS SOLID BLUE STREAK OF AWESOME ELECTRICITY. It has been a long time since I've been that relieved and happy (well within the last two weeks since I've been working on it anyway). So then after that, I went through individually checking each plug. Sure enough each one of them had spark.

On to the next chapter, I thought perhaps I should push my luck a little tonight since it was going so well, so I grabbed some ether and gave the top of the carbs a little spray.... and turned the engine over a few times with no throttle or anything and cough cough cough cough... my heart stopped for a second, to be completely honest I didn't quite believe what I heard. So real quickly i resprayed some ether and opened up the throttle a little bit and.....VRROOOOOOMMMMMMMMMMMMMM :toocool:

Anyway, lessons to be learned is A) I'm not out of the clear yet, I still got some work to do and I only heard it for a few seconds but those were glorious seconds B) 3 of 4 cylinders in the beginning were reading 30PSI, so I suspected some burnt rings after I dropped a little oil in each of those cylinders and it sealed up C) Pretty amazing it can run in that kind of shape, but next step will likely be trying a continuous gas flow and see if she runs (and not being surprised if it runs crappy - but running would be cool, and go from there, maybe some mystery oil may help free up the rings) D) In the beginning I should have replaced all the spark plugs right off the bat when doing my spark plug test, those babies were old, it makes me wonder if those kept me from seeing any spark whatsoever, I do remember cleaning one of them and still not seeing spark. However, my conundrum is, when I did it, I'm not sure if I had all the rest of myspark plugs set in their cylinder holes. In other words, I'm still not sure if 3 of 4 at all times need to be grounded to a cylinder to have the 4th one show spark. I may do some investigating, but there is a STUPID good chance the reason I wasn't seeing spark was because of bad plugs straight up (I guess I just thought I would have thought of something, and I even tried a single new plug when checking for spark but I can't remember if the rest of the plugs were grounded). Even in the beginning I tried spraying either and I had nothing. So something definitely changed. E) I guess at the end of the day, I wish I would have just kept it simple stupid. Gonna try to see if I can get the ole girl to idle tomorrow.

I really appreciate your help HIS OWN 6 - sorry for being dense on this end, I hope this discussion helps someone else along the way. And possibly the reason I jumped to conclusion is this bike had not been ran in 10 YEARS and raced on a track... I thought all sorts of bad things had happened to it, it was in rough shape. Two weeks later I'm hearing combustion .... WHOOOOOOOP!:usa now that's the sound of freedom.
 

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Mr. HER6
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Gotta love that feeling of joy and relief when you manage to get things working. Good luck with the rest of your project. :cheers
 

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Discussion Starter · #14 ·
Just an update here. Really appreciated all the support. Bike needed a carb clean in a bad way. Wouldn't run without ether. The jets were visibly clogged. Cleaned em all up. And she fired right up. Took it forget maiden voyage around the block today. Probably the first time she has hit the road in over a decade.

Now rebuilding the rear brake master cylinder and caliper.

Everything is good!
 
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