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Author Topic: Help me find spark on my SR500  (Read 2515 times)

Offline scott s

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Help me find spark on my SR500
« on: Sep 10, 2018, 08:58:55 »
 I recently picked up a 1980 SR500 that's been off the road for years:  http://www.dotheton.com/forum/index.php?topic=75801.0

 I can't get spark for the life of me. I did the test procedures from Rex's Speed shop.

https://drive.google.com/file/d/1ds48JON5ZCEoU92-dm269MFteAf1Pj-t/view

 Initially, the only thing that came back wonky was a very HIGH reading on the coil secondary. Usually low or open is bad. Either way, ordered a new coil from Rex's. This is the proper 1 ohm coil with proper grounding for CDI, etc.

http://www.rexs-speedshop.com/epages/es143131.sf/en_US/?ObjectPath=/Shops/es143131/Products/HTC10

 Installed that and still no spark. The test procedure tests the wiring going TO the CDI, but there's no way to really test the CDI. So, I ordered a new CDI from Rex's. Still no spark.
 I've gone through the test procedure twice more. I've done it with and without a battery in the bike (the SR500 will run without the battery. The battery has nothing to do with the ignition). I can't find anything wrong.
 One slight oddity, and I don't think it's an issue, is that my Radio Shack meter reads on a 200 ohm scale, then goes to a 2K ohm scale. Some of the stator windings are supposed to be 330 ohms. I use the 2K ohm scale and get readings with a decimal in front. BUT....isn't .330Kohms the same as 330 ohms?
 Rex's is telling me to sort out the issue with the meter, but if I understand it correctly, those readings are good.



 -I checked that the stator and flywheel are matched. They are.
 -Tried a new plug and the old plug.
 -Pulled the sprocket cover and checked for frayed wires from the stator (even though tests are good). Found nothing.
 - Checked from the coil to the CDI and get the same 0.9 ohms (good).
 - Tried unplugging the kill switch. No spark.
 -Checked the gap on the pickup and got .030-.032, so good.

 And on and on and on. What next? Why don't I have spark?
 

Offline scott s

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Re: Help me find spark on my SR500
« Reply #1 on: Sep 10, 2018, 13:39:20 »
I tested the kill switch.
 I have continuity from the connector in the harness all the way to the CDI plug on both the Black and Black/White wires. I get 0.9-1.0 ohms on those wires.

 I tested the operation of the switch itself and I get:
 OFF 0.4 ohms
 ON  Open, or infinite
 OFF 0.5 ohms

I tested the key switch, going from the Black to the Black/White in the 4 prong plug.
 OFF 0.2 ohms
 ON Open, or infinite.

 I am pretty confident at this point that I do not have a broken wire anywhere in the wiring harness. EVERY test that I do tests good, at least to the best of my ability. I'm stumped and frustrated.

Offline Hoofhearted

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Re: Help me find spark on my SR500
« Reply #2 on: Sep 22, 2018, 03:03:41 »
I never had an SR.  I did have an SRX which had a habit of losing the spark,  I don't know if your SR came with a sidestand "kill" switch.  The SRX had one.  If you do have a sidesatand switch take a look.
El Mirage record 500 APS/PG 129.817
El Mirage record 500 SC/PG   122.240
El Mirage record 500 SC/PF    120.157
Bonneville record 500 SC/PG  119.667
Bonneville record 500 SC/PF   117.186
Bonneville record 500 SC/PBG  111.494
Bonneville record 500 SC/PBF   112. 600
Bonneville record 650 SC/PF   128.703
El Mirage  record  650 SC/PG   130.224

Offline scott s

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Re: Help me find spark on my SR500
« Reply #3 on: Sep 22, 2018, 07:46:25 »
 No sidestand switch.

Offline scott s

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Re: Help me find spark on my SR500
« Reply #4 on: Jan 19, 2019, 09:14:56 »
 Bumping this up because, guess what? I *STILL* have no spark!

 After testing, testing and more testing, I sent it to my friends shop in Charlotte. He's had it for a few months now (he's mostly European bikes these days, so I was thankful he'd take a look at it) and he can't get spark either.

 His tests on the stator came back bad/low. I may have missed that because I was using a cheap meter and my scales jump from 200 oHm to the kilo-oHm scale.
 He sent the stator to Rick's for a rewind. When it was returned, one of the pick-ups was hitting the flywheel. Sent it back to Rick's and they fixed it. Still no spark.
 My mechanic has traced out the entire harness, just like I did, and found nothing. Tried removing the B/W wire from the CDI (it grounds the spark, killing the engine) and that didn't work, either.

 We confirmed that I ordered the correct CDI from Rex's (I did). We asked Rex's to test both the old and new CDI units but they declined, saying that taxes, import duties and fees make it not feasible.

 -New correct coil from Rex's (includes cap)
 -New plug
 -New CDI
 -Stator rewound
 -Harness and controls checked
 -Confirmed stator/rotor/flywheel match
 -Confirmed rotor has't spun on the crankshaft
 -Checked, tested and cleaned multiple grounds

 Now what?

Offline J-Rod10

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Re: Help me find spark on my SR500
« Reply #5 on: Jan 19, 2019, 10:02:50 »
If the CDI is a spark box like on the DOHC Hondas, it sounds like you've gone through every thing but the ignition system itself.

Charging system shouldn't be the cause of no spark, until the battery is drained.

Offline scott s

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Re: Help me find spark on my SR500
« Reply #6 on: Jan 19, 2019, 10:16:37 »
 I've gone through the ignition system. The coil/wire/cap was replaced with a brand new, correct coil from Rex's. The CDI was replaced with a brand new, correct unit from Rex's. That stator was rewound at Rick's.

 And, correct me if I'm wrong, but the battery isn't needed to make spark on an SR500.

Offline J-Rod10

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Re: Help me find spark on my SR500
« Reply #7 on: Jan 19, 2019, 13:24:58 »
I believed a battery, or capacitor, is needed. Though, I could be wrong as well.

Certainly sounds like a head scratcher. Hope you get it sorted.

Offline scott s

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Re: Help me find spark on my SR500
« Reply #8 on: Jan 19, 2019, 15:34:55 »
 I've tried it with the old, dead battery and a brand new battery.

Offline wozza

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Re: Help me find spark on my SR500
« Reply #9 on: Jan 19, 2019, 22:20:21 »
Have you tried removing the plug and checking the spark with the bike in  high gear and spin the rear wheel ?
sometimes the magnetic field is weak and the kick starter cant spin her fast enough to throw a spark..push starting can sometimes work....
also have a look ere maybe there is something that will help
https://yamahaclub.com/forums/topic/8213-78-sr500-no-spark/