Topic: 1980 SR500... In search of spark

[Scott S]

Picked up a 1980 SR500 that's been off the road for more than a decade. It is my understanding that the SR500 doesn't need a battery to get spark.
 Out of curiosity, I pulled the plug today and grounded it on the head. Key on, kill switch ON, kicked it over..... No spark.


I ran through the test procedures here: https://drive.google.com/file/d/1ds48JON5ZCEoU92-dm269MFteAf1Pj-t/view

I installed a new NGK XB05F cap and a new NGK BP7EX plug, gapped correctly.

I also followed the procedures to test the coil from another post on the site.

I failed to write down the numbers for the kill switch (my Dad was calling out the procedure and I was relaying the readings), but everything passed.
All of the readings for the stator/magneto/generator...whatever it's called...also all passed. I do have those numbers written down and can scan it if you really think it's necessary.

The ONLY thing that threw up a flag was the Secondary reading from the coil. The factory manual and Rex's said it should be ~11K ohm's (Rex's said 7-14K). I'm seeing EXTREMELY high numbers on the secondary. I saw 38.2K to 39.0K without the plug cap, and 49.0K with the cap.
I'm kinda dumb when it comes to electrical, but that all points to a bad coil, no?

The only other thing I can't rule out is a bad TCI/CDI unit, and you can't really test that other than trying a replacement.


BONUS QUESTION: I noticed that the outer generator cover didn't seem to have a ton of magnetism to it. I've worked on some Honda CB/CL twins and they would actually grab a screwdriver away from you. This one IS magnetized, but it seems a bit weak. Does that mean anything? This bike probably hasn't run since at least 2006.


 Sent Rex's and email and they agreed that their bet would be on the coil. Ordered a new coil.

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

Installed new coil today. I still don't see a spark. I can't see a spark when grounding the plug to the head. I also put my multi meter on 20V DC and grounded it to the head and put the POS lead into the spark plug cap. I checked to see if it changed when kicking it over and didn't see any voltage.

I plan on getting a fresh battery for my meter and doing all the tests again. I also have a new AGM battery for the bike I can install, but it's my understanding that has nothing to do with seeing spark.

I sent Rex's a follow up email. Any ideas or suggestions on what to check next?

[briandk]

I know for sure you don’t need a battery as my garage buddy has a SR500 without, but he has a capacitor installed instead.

[Scott S]

 I'm not trying to run it this way, only checking for spark. I guess I'll put the new battery in, since it's going in anyway.

[Scott S]

I now have a new coil and new CDI and I still don't have spark.

 I installed a new battery in my meter and did these tests again: https://drive.google.com/file/d/1ds48JON5ZCEoU92-dm269MFteAf1Pj-t/view



 I did the test procedures and originally got high ohm's on the coil, so I installed a new coil. Still no spark. Then I installed a new CDI. Still no spark.

 Today, I did the test procedure again. I *think* that everything is OK except maybe test 1C on the ignition switch/kill switch.

 Also, I have a cheap meter (new battery for this round of tests) and the sheet says "0.95-1.1R" for the Primary resistance. I'm not sure what the "R" means. I used the 200 OHM scale as that is as low as my meter goes and, since the coil is new, I left the cap on so as not to disturb anything. I got 9.0 ohms on the Primary vs. the "0.95-1.1R" but, like I said, I'm not sure what that R scale means.

 Would the 5.0 Ohms on the test 1C be my problem?

 I did notice this time that even with no battery installed, I saw the Neutral light come on when kicking it over. I just don't see any spark.

 Test page attached. Any help you can offer is much appreciated.

[CBJoe]

I had thought that R = Resistance which is measured in Ohms....I'm pretty sure that 1.1R = 1.1ohms

I was looking for electrical diagram for the SR500 and found this thread on google....someone breaks down the SR500 Ignition System a bit down the page (post by JoeSchmo)   https://yamahaclub.com/forums/topic/8213-78-sr500-no-spark/  Also indicates primary resistance should be .98 ohms (1 ohm) and the secondary should be 12,000 ohms.  So if you are reading 9ohms on the primary thats not right.

Maybe it wont tell you anything you don't already know but I thought to pass it along.  Seems the SR500 had some stator issues...

On your Multimeter...did you ohm out your leads to be sure you aren't having inflated resistance readings due to bad leads?

Joe

[scottly]

It looks like the SR ignition system is similar to the FT Ascot. The only part of test one that allows the engine to run is 1D, which your test was good; the other parts are the switch conditions that prevent the engine from getting a spark, by grounding a lead to the CDI unit.
The very high 9 ohm resistance of the coil primary is the only measurement waay out of line; perhaps it was actually .9 ohm?
A word about self-generating CDI ignitions: at low RPM, such as when kicking, they tend to produce a very narrow, fast spark, not like the fat spark seen with an inductive discharge system. It can be easy to miss in broad daylight. Got a nephew that pisses you off? Have him grab the shank of a screw driver shoved into the spark-plug cap while you kick the bike over. If his arm involuntarily jerks violently, you have spark.  

[Scott S]

 Perhaps it is, AND it was done with the cap on, since the coil is brand new and I didn't want to disturb the connection. I know the cap adds resistance.
 This is the coil I bought and it's supposed to have the correct resistance, grounding ring, etc.

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

[Scott S]

 "Got a nephew that pisses you off? Have him grab the shank of a screw driver shoved into the spark-plug cap while you kick the bike over. If his arm involuntarily jerks violently, you have spark. "

 No, but I have a GF! Can I use my meter in the plug cap and see if I see voltage when kicking?

[calj737]

No, but I have a GF! Can I use my meter in the plug cap and see if I see voltage when kicking?

Yes, you can use a meter. I’ve met your GF, best you use a meter lest you want to be added to the Memorial Board

[CBJoe]

No, but I have a GF! Can I use my meter in the plug cap and see if I see voltage when kicking?

Yes, you can use a meter. I’ve met your GF, best you use a meter lest you want to be added to the Memorial Board

 

[scottly]

The spark plug cap will not affect the primary resistance, only the secondary. 

[Scott S]

 Right...so if Primary resistance should be 0.95-1.1R and I'm using the 200 Ohm scale, and I get 9.0, is that the same as 0.9 "R" if I had a meter that used a smaller scale?
 I doubt it's the coil as it's brand new; see link above.

 I'm being told to check for a mismatched flywheel/stator. I'll probably pull the cover off tomorrow and look at that.

[scottly]

What reading do you get with the two meter leads connected together? And no, you can't check for spark with the meter; the spark is too brief for the meter to react, and the voltage is too high,like 15,000 volts.

[CBJoe]

Right...so if Primary resistance should be 0.95-1.1R and I'm using the 200 Ohm scale, and I get 9.0, is that the same as 0.9 "R" if I had a meter that used a smaller scale?
 I doubt it's the coil as it's brand new; see link above.

 I'm being told to check for a mismatched flywheel/stator. I'll probably pull the cover off tomorrow and look at that.

No....1R should = 1ohm   Pretty sure that the primary resistance should be < 1ohm....so I'm guessing that the scale on that coil reflects that.

For sure ohm out your multimeter leads by simply touching them together and seeing what they say....if you have a reading then the ghetto method is to discount that as an offset.  So if you read 3 ohms just subtract 3ohms from your total reading.  But truly a 200ohm scale to try and read < 1 ohm is guaranteed to not be very accurate.

Joe

[scottly]

Would the meter in question happen to be a Cen-tech from Harbor Freight? I just checked one and with the leads touching it read 009 on the 200 ohm scale.

[scottly]

Just noticed that when the meter is first switched to the 200 scale, there is a decimal point, which quickly fades away, so the reading is actually 00.9.

[Scott S]

 It's a Radio Shack meter. I ohm it out and get 0 or 0.1. This is the reading I get on the primary, so it seems to be good.



 This is test 5 Brown to Black. Should be 330 Ohms. I used the 2K ohm scale and I get .338. Notice the decimal.



 This is Test 7, Red to Black. Should be 330 Ohms, I get .330. Again, with the decimal. Is that a function of my meter? Is that 330 Ohms?

[Scott S]

 This is the flywheel. The number is 03200-077.



 There is also a 3H1-50...



 ...and a 2  10  S

[Scott S]

 The "fat" winding on the stator, which I believe to be the Low Speed Pick-up, is at the 9 o'clock position.



 There is another slightly different colored/shaped winding at about 1 o'clock, but it's not as fat as the one at 9 o'clock. All of the rest of the windings are the same shape/size/color; a brown or copper color and much smaller that the one at 9 o'clock.

[scottly]

Yes, .330 Kohms is 330 ohms.
Don't know about the part #s... Is the flywheel indexed to the crank shaft with a key? If so, is it possible the key has sheared?

[Scott S]

 I'm told that there are at least three different flywheel/stator combos, or more. They must be matched. If someone has changed the stator but not the flywheel, that could be it.
 I checked again tonight with the old spark plug, new plug, screwdriver in the cap, one of those spark plug test light things.... I'm just not getting spark.

[scottly]

Can you post a schematic diagram?

[Scott S]

 I'll look. I have a factory manual that cam with the bike but it only goes to '79, or the F model. I have a 1980 G model, so there may be differences.

[scottly]

I found one, but it's not very clear. Rex's test procedure had you check the coil primary at the coil itself; try making the measurement at the three wire harness plug at the CDI end. Disconnect the plug, and measure the resistance across the orange and black wires; it should be the same .9 ohms measured at the coil. Also, check between the black wire and the frame/engine; should be zero ohms.

[Scott S]

 You mean on the main harness where the CDI plugs in? I think the tests do that too, but I'll do it again.