Confirmation on CDI wiring bypasses (trying ro remove variables on a weak spark situation) - Kawasaki KLR 650 Forum
1987 to 2007 Wrenching & Mods For maintaining, repair or modifications of Generation 1 KLR's. 2007 and earlier.

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post #1 of 18 Old 01-19-2020, 02:22 PM Thread Starter
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Confirmation on CDI wiring bypasses (trying ro remove variables on a weak spark situation)

Hello. I am not new the KLR or wrenching on machines, though I somehow am new to this site. In 15 years of owning my 03 this is the only time I've been totally confounded. I am approaching the point where I have to set this thing on fire and take it in for scrap--I just can't track this down, and these days this has become a commuting tool 60 miles to/from new york city... which means a failure to start could yield tow bill in excess of the bike's value. The problem is an intermittent hard/no start. I have been through a lot of diagnostics and believe it is spark related. All electrical components ohm out ok (exciter coil, p/u coil, primary and secondary, CDI) and the loom also ohms out (ie there is not a complete lack of continuity apparent between the corresponding ends of any circuits). I have tried a new plug, and have also swapped in a believed-and-tested-good CDI and primary coil/wire/plug cap from another KLR with no effect. The standard safety switches and the starter safety relay were eliminated 50k miles ago, the stator is stock.

If you hold the plug electrode to bare metal, it *has* spark, but it's anemic and yellow. I suspect it is an intermittent break somewhere creating either a poor connection in something that should be conducting, or a worn insulation allowing some juice to leak to ground, but careful visual inspection hasn't turned anything up. Also, my inductive timing gun can't pick up the pulse in the sparkplug wire (I discovered this while trying to confirm the timing was correct, even though I know we can't adjust it). So we DO have spark, but the spark is terrible, verging on nonexistent. Once/if the bike manages to start, it ran/runs fine, for whatever that's worth.

I bought a thing like this



...to try to objectively measure the spark strength, and I can't get it to jump at even the "small engine" setting. In fact, I have to be about 1 turn out from fully closed before the spark can gap, and you have to have your eyeball right on the thing in the dark to see it. I've of course never used it on a healthy KLR so I have no baseline, but I've seen specs for Kawi dirtbikes in the 20-30k range, so I have to believe even a lazy KLR should manage 10k, and I'm WAY under that.

I want to use jumper wires to bypass the loom and the igntion switch entirely so the CDI is in a permanent "RUN" state, and see if the spark is healthy then. I believe with all the safety crap out of the way the starter will still run, but I can jump the starter to spin the motor if I need to, I just need to confirm the ignition circuit is all wired for running.

I started here:



...which simplified down to this after skipping all the safety crap...



which is:
PICKUP COIL (2 wires) <--> CDI
EXCITER COIL (2 wires) <--> CDI
12v+ <--> CDI (B/Y wire by itself)
Chassis ground <--> CDI (B/Y and also R/B, which used to go to diode pack)

I would appreciate any confirmation that this is logical. I've read you can toast a CDI if it doesn't have correct grounding (ie you turn it over with the plug lead disconnected) and while I've definitely done that on many engines accidentally, I'd like to minimize my losses here.

Thank you.

Luke
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post #2 of 18 Old 01-19-2020, 02:58 PM
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The onset of intermittent hard-starting is often a sign that the valve lash has become too tight.

Have you checked the valves for proper clearance? They should be set towards the maximum amount of clearance.

Tom [email protected]

“I still held his automatic more or less pointed at him, but he swung on me just the same. It caught me flush on the chin. It was meant to be a hard one, but a pansy has no iron in his bones, whatever he looks like.” -Philip Marlowe

“'Why' and 'How' are words so important they cannot be too often used.” -Napoleon Bonaparte

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post #3 of 18 Old 01-19-2020, 04:00 PM Thread Starter
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Quote:
Originally Posted by Tom Schmitz View Post
Have you checked the valves for proper clearance?
I agree with that, but the valves are correct. Also has good compression. KACR is intact and functioning. The hard/no start doesn't seem at all temperature related (neither ambient nor engine temp related)--it has occurred from a cold start in the low 40's to a warmed up engine with upper 80's ambient. I thought maybe the timing chain had jumped and reset it as part of pulling the stator cover off, but the problem is still there. The bike won't cough on ether, which to me rules out fuel, though I've gone through the carb twice just for fun. Air cleaner has been cleaned, and I've tried cranking without it entirely. I also tried jumping around the ignition switch, in case it was failing internally such that it would allow cranking but also ground the B/W wire at the same time. I really think it is somehow ignition related. I would like to confirm the timing is still correct but the spark pulse through the plug wire is too weak to trigger the timing gun... which I've used on everything from a 1950's tractor to aircooled VW's to my wife's modern subaru without fail.

I guess I'm going to start bypassing the harness bit by bit per the drawing above and see if I can get a quality spark. If not, about the only thing left to throw at it is a stator. I despise throwing parts as a strategy, but this bike is a pile of scrap steel to me if I can't trust it to restart and I'm at the end of the rope.

Luke
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post #4 of 18 Old 01-19-2020, 04:55 PM
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OK. Have you checked the output of the exciter coil at cranking speed and while running and checked the wires exiting the alternator cover for good insulation and continuity?

What I have found, though not so young as an '03, is wires with expired insulation due to exposure to heat and oil/chain lube. I have found the wires inside the cover to be in the same state, though they don't tend to crack and fail because they don't move around.
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Tom [email protected]

“I still held his automatic more or less pointed at him, but he swung on me just the same. It caught me flush on the chin. It was meant to be a hard one, but a pansy has no iron in his bones, whatever he looks like.” -Philip Marlowe

“'Why' and 'How' are words so important they cannot be too often used.” -Napoleon Bonaparte

Sting like a butterfly.
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Last edited by Tom Schmitz; 01-19-2020 at 04:57 PM.
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post #5 of 18 Old 01-19-2020, 04:55 PM
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Couple of things.

First I will ask, Exactly What was your Cold Cranking Compression measurement! I never trust "good enough" statements. Was this reading with Active KACR or De-Activated KACR?

There really is not need for a spark checker tool. Unscrew the plug cap from the ignition coil wire. Hold the exposed end near a valve cover bolt & gently draw the wire Away from the well grounded cover bolt. HOW much arcing distance does it consistently achieve, 1, 2, 3, 4, 5, 6, 7 mm? Are you working in Bright Sunshine or a Dim Garage? Dim garage is best for this.

When in doubt, HOLD on to the bare coil wire and CRANK IT! I have never been able to HOLD onto Both the coil wire and the starter button of a GOOD system. I will let go of one or the other.

pdwestman
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post #6 of 18 Old 01-19-2020, 05:30 PM
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Are you also certain that all of your electrical connections, to the battery and to the frame, are clean and tight? More than one issue has been due to poor connections.

I was going to suggest that if you can hold onto the bare end of the high tension lead while cranking it, then you have a weak spark. I thought it might be taken as being facetious (it's not!) and you are indicating an intermittent issue. As Paul suggested, try it. Neither of us has ever been killed doing this, not even once.

Tom [email protected]

“I still held his automatic more or less pointed at him, but he swung on me just the same. It caught me flush on the chin. It was meant to be a hard one, but a pansy has no iron in his bones, whatever he looks like.” -Philip Marlowe

“'Why' and 'How' are words so important they cannot be too often used.” -Napoleon Bonaparte

Sting like a butterfly.
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post #7 of 18 Old 01-19-2020, 06:25 PM
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Fundamental to igntion power, seems to me, is the exciter coils' output. We're talking AC here; switch your meter! Static testing: W-BK, 61-114 ohms (KLR 600); understand these check OK.

If weak spark appears the problem, have you tested ignition coil (not found in my reading of your posts above) primary and secondary resistances? Substituted a known good ignition coil?

Otherwise, I harbor the controversial notion the cylinder compression specification (70-114 psi for KLR 600) remains too broad for useful, precise diagnosis (without historic pressure readings for comparison). A leak-down test might define compression health more fully, given a functioning compression release.

Clean, tight connections reflect sound maintenance; however, the battery circuit remains separate from the ignition circuit on Generation 1s.

“You better put down that gun. You got two ways to go, put it down or use it. Even if you tie me, you’re gonna be dead.” "John Russell" (Paul Newman), Hombre
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post #8 of 18 Old 01-20-2020, 01:38 PM
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I will 2nd checking coil. I've had a Gen 1 develop weak spark, and it got weaker as it got hotter. A new coil fixed it.
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post #9 of 18 Old 01-21-2020, 06:52 PM
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I went through a nightmare with a Yamaha 1100 Special that had ignition issues that turned out to be corrosion on the contacts of the power switch on the right grip.
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post #10 of 18 Old 01-23-2020, 06:14 PM Thread Starter
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Thanks for all the feedback. I understand "is good" raises an eyebrow when we don't know one another. The bike won't start right now, these tests are with a charged battery (reads 13.1v with the ignition off) cranking in neutral where appropriate. I didn't note what the RPM when cranking is, but it sounds normal.

In order of questions:
The output from the exciter coil is currently 37v AC measured at the plug near the CDI. I seem to remember it was 42V last winter when I checked but I can't find where/if I recorded the exact value (I just noted it was "ok"). I went through EVERYTHING last winter trying to nail this, and just forced its intermittentness undercover so I thought it was solved or maybe a loose terminal or something, then damn near had to rent a trailer to get the thing home from the city... I kept some of those measurements but not all. Likewise I noted last winter that the exciter coil resistance checked out as ok, but didn't record in my maintenance log what that was. This evening I'm seeing 200 ohms with the ratshack analog meter and 280 with my Flukes. They say a man with one watch knows what time it is, a man with TWO watches is never quite sure. I trust the Fluke more except in places where the higher current of the analog matters (like the CDI itself). Both those values are a bit over the spec of 100-200 ohms.

I can't test the exciter oil output when running because it won't run at the moment.

This thread (https://advrider.com/f/threads/klr65...-query.738488/) offers *cranking* values between 30v and 60v ac (pretty big range!). I have no baseline for the measurement on this bike prior to this issue (never had reason to measure it that I can recall). Interested in input.

The wires from the stator show no visible damage inside the case nor out, but that's one of the definite possibilities. I have a pic of the stator itself I can post (from last winter) but it looks like others I've seen. It didn't occur to me to meter from the presumably bare wire exiting the stator windings inside the case to the terminal end of the wire for resistance. I will certainly do so the next time I have the case open.

Compression: 70-90 with KACR intact, 160-190 with the KACR disabled with a little stub of hose in the works. Those numbers are on a cold engine that hasn't been started for a while and hasn't had oil squirted in or anything; range is because I'd borrowed an additional tester to verify I wasn't using a lousy meter. The bike has around 15k on a fresh 685 and it doesn't live a super hard life anymore... the 685 took it from an oil guzzler to using almost nothing from one change to the next. My chinese static leakdown tester crapped the bed so I can't apply that, but those numbers seem very fine for a 650/685 to me.

With the plug cap removed from the wire I can see a spark jump a 3mm gap to bare metal on the engine. I used a caliper to measure that gap as best I could (tried to brace my hand so the gap wouldn't change while I measured with the caliper after releasing the button). Again, I've never tried that test before so? This is in a dim garage, easy to see what spark there is. Interestingly spark looks bluer this way than across a grounded plug.

I can crank the bike with my thumb held squarely over the end of the bare high tension wire. I can definitely feel the juice, but it isn't painful. I would say I am no more than average on the pain threshold, though I do work with electricity so the sensation of getting "bit" is not as new as I wish. This seems very vague, though, since the path to ground is presumably through my other hand on a rubber grip pushing a plastic button, no? Kind of why I got that metered spark tester gizmo--to remove the estimation.

Battery connections (+ and -) are good and clean. I don't think I've EVER disturbed the negative lead where it connects to the motor near the starter though. The ground up near the steering head is also tight and clean. Part of why I want to jump the CDI into a running state is to cross all that off: With an old CDI ignition like this, as long as the rotor is spinning past the stator and the wires between to the CDI then to coil and plug are solid, the only that's relevant is the CDI back to the block. It seems possible that somewhere in its path through the key and through the kill switch there could be either a lousy connection OR a worn insulation allowing a slight leakage to ground.

Coil is checked and very near spec AND I recently bought a second used coil which also checks to near spec. The resistance on the primary coil is so tiny (.15 to .21 ohms per Clymer) that it's awfully hard to really get good resolution, but it's not shorted nor open for sure:
Original coil .1 (fluke) and .2 (analog ratshack); eBay coil .1 (fluke) and .25 (analog ratshack)
Original secondary with wire 3200, eBay secondary w wire 4450 (spec is 3800-5800)
Original plug cap 4000, eBay plug cap 4600 (Clymer references 5,500 as an unofficial number but says Kawi didn't offer one)
On top of that, last winter I borrowed a known good coil complete through the plug cap off my father's bike (they live 700 miles away but were visiting) and that did not cause the bike to roar to life.

I'm interested in input on any of this and any more guidance. I'm going to try to jump the coils directly to the CDI and make a temporary CDI ground if I can confidently get that much crap into the terminal block without risk of a short. I really need to actually find and resolve this problem; with the way I rely on the bike now, getting it running again won't be acceptable if there's the risk this will recur. I thought I had it licked last spring and it damn near got me fired over the summer.

Luke
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