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1987 to 2007 Wrenching & Mods For maintaining, repair or modifications of Generation 1 KLR's. 2007 and earlier.

Thread: Confirmation on CDI wiring bypasses (trying ro remove variables on a weak spark situation) Reply to Thread
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  Topic Review (Newest First)
03-03-2020 02:06 PM
Originally Posted by pdwestman View Post
Did you by any chance check for continuity between Exciter coil wires and ground?

Resistance thru the 2 wires could be proper, but could have a high ohms leak in the middle. Might could still test to stator core.
Yes--I checked for continuity to ground on both exciter and pickup coils with nothing amiss...
03-02-2020 07:17 PM
pdwestman Did you by any chance check for continuity between Exciter coil wires and ground?

Resistance thru the 2 wires could be proper, but could have a high ohms leak in the middle. Might could still test to stator core.
03-02-2020 05:26 PM
ldeikis Ok. I am extremely reluctant to say I've solved an intermittent electrical problem... but I think I concretely identified the problem and replaced it, and the bike started right up and I've objectively confirmed healthier measurements several times. So... maybe?

The issue was a worn stator... however it passed all the static resistance tests right on the money. I can only conclude that there's some kind of small break in one of the wires from the exciter coil that is allowing the tiny current of the resistance test to flow unhindered, but that with the increased current of actually charging the CDI, it experiences voltage drop that lowers the CDI to just barely able to fire. Perhaps the exception that proves the rule of modern electronic ignition components either work or don't work. This one worked, but not enough. Extremely close inspection, even once I'd fingered the thing as bad, did not turn up any visible damage to the wires.

Important piece of data was AC voltage measured between red and white wires where the stator harness meets the rest of the bike. Cranking with a healthy battery and a healthy but used OEM stator, correct value seems to be around 60v AC. I am now getting around or slightly above that. I have only found a couple references online to this value and it is not in the Clymer book. When I started this process, I was getting 37v AC pretty consistently. Which is apparently enough to barely sometimes start.

Other troubleshooting points I discovered:
The pickup coil generates around .2v AC.
Also, if you're chasing a no spark situation, meter the pickup coil and exciter coil both at the end of its harness AND at the main harness where it plugs into the CDI. I inadvertently bent one of the little spades inside the p/u coil plug with a probe somewhere along the way and suddenly had NO spark instead of weak spark. It took me a while of metering and jiggling to identify the issue, since when I disconnected and metered the harness from the p/u coil there WAS current being generated there.
Also, yes, the pencil electrical diagram I posted upthread RE CDI wiring is correct. I did go ahead and replace the bits of the harness between the stator plug and the CDI plug with correctly-colored 12g wire, attached via the OEM plugs. Why not.
Also, I still can't get my timing gun to trigger from the induction clamp on the KLR's spark plug wire... so I can't weigh in on the great Y/B wire controversy.
Last, this little Lisle spark tester DID turn out to be quite helpful, though the thumb on the bare spark plug wire is also a useful gauge. Strangely, I am still getting slightly inconsistent spark strength, but even the weaker ones are exponentially stronger than where I started, so...

I am cautiously optimistic that I sorted this out. Time will tell.

Attached are before and after pictures with the Lisle thing. It is imperfect, but useful.
01-25-2020 01:18 PM

I'd love to be able to compare data on objective spark strength if anyone out there has a Prime account and a desire to spend $13 on one of these things...

So I made up a bunch of tiny 12g jumpers with itsy bitsy spades on them and jumped the CDI directly to the appropriate leads from the exciter and p/u coil, and to the ignition coil and a direct ground. I tested it with the little lisle sparkometer and it is definitely a stronger spark--the spark will consistently jump across two full turns out now, and is a sort of intermittent completion at 2 1/2 turns; I no longer can hold my thumb on the end of the spark wire with cap removed. Then I realized that the plug cap wasn't firmly tightened onto the coil wire since I had it off this week to test resistances--tightened that up and am now getting a spark jumping across 4-turns-from-closed on the Lisle meter.

Unless the wires run somewhere illogical inside the loom and build up extra resistance instead of taking direct paths, the only thing I seem to have removed is the possibility that the B/W wire was finding a very weak ground on its way up or within the ignition and kill switch, OR my direct ground to the battery has lower resistance than the loom grounds offer to the coil and CDI (the ground through the safety circuits is solid as I jumpered it before the diode a while back), OR it's an intermittent electrical problem that has gone back into remission.

I pulled all the jumpers out and reconnected all the harness connectors (with the same CDI, coil, plug etc) and it would barely jump 1 turn out on the tester.[/B] I reinstalled the jumpers: 4 turns. Reconnected full harness: 1.5 turns. If I hadn't been chasing this intermittently for so long I'd declare a major step forward, but this is a good sign.

With these jumpers still in place I hooked the plug up and she still wouldn't start, but she DID catch with a shot of ether and some cranking, which was not effective when it was acting up in the past. The bike's been sitting 6 months with minimal prep when parked so I'm not surprised the carb needed a kick in the pants.

I don't feel like I've solved anything, but I'm maybe making progress. I'll untape the loom up to the cluster and look for bare spots, and also try to isolate which circuit is the culprit. If it seems easy I may also intercept that B/W wire near the CDI and rig a temporary kill switch that doesn't have so much opportunity for issues. I am suspecting ignition, kill switch, or the ground. I have an entire spare engine from a wrecked bike and my next step will be to pull the case apart and yank the stator... I have been reluctant to do so because as far as I know that other block is a complete engine and it is more valuable as such than as another milkcrate of parts... Wish I hadn't sold my other other spare engine now.

I would love the chance to compare objective spark strength with someone's healthy gen1 KLR. Replacing the loom is a solid idea, but I might prefer to buy some heavier wire with the correct colors and roll my own replacements for the ignition circuits, at least--between ditching the safety circuits and adding a trailtech I already have a lot of vestigial OEM wires running around that don't do anything.

01-23-2020 08:02 PM
Originally Posted by pdwestman View Post
A brand new main wire harness is less than $70. Ya' I know this is an '07, should be identical to an '03 even if numbers are different.

Maybe I ought to purchase a spare harness & have a fuse on my '87 cooling fan!

I am leaning towards a Weak Exciter coil on the stator.
The only difference I noted with the newer harness, is that the rear brake switch connector is Gen 2 style (better), requiring that P/N switch. A new main wire harness is IMO a cheap way to refresh an old Gen 1 KLR, and improve reliability.
01-23-2020 07:45 PM
pdwestman A brand new main wire harness is less than $70. Ya' I know this is an '07, should be identical to an '03 even if numbers are different.

Maybe I ought to purchase a spare harness & have a fuse on my '87 cooling fan!

I am leaning towards a Weak Exciter coil on the stator.
01-23-2020 07:10 PM
Damocles Maybe the problem ain't the low spark entirely; suggest you try starting the bike with starting fluid (more flammable than gasoline). If the engine runs on starting fluid, but not gasoline, the mixture may be the problem.
01-23-2020 07:01 PM
GreatWhiteNorth 2+ years ago I bought a KLR from motorcycle salvage, got it home, found it had no spark... did a bunch of troubleshooting, swapping CDI box, coil etc (had spares), changed out the main wire harness too (they are cheap from dealer, under $100), so looked at the stator and crank position sensor as a possibility. I found multiple issues, cracked broken wire insulation in multiple spots:

There's even a bad spot inside the case:

Swapping in a spare LH case assembly with good stator and crank position sensor (coil pulsing) fixed it.
01-23-2020 06:14 PM
ldeikis 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.

01-21-2020 06:52 PM
terry_g 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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