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Makotosun

This bike don't exist? No spark, been garage kept for 37 years.

  • Yamafam#1
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I connected black wire from stator to ignition coil turned the light out and had my son Kick it over with no spark. I checked ohms from black stator wire to ground with points open and got 1.4 and the same in the closed position. I have 9.7 k ohms from coil wire to plug boot. 0.6 ohms from coil wire to ground also has continuity to ground if that means anything.
27 Nov 2020 14:54 #11

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With points closed, you must have a zero ohms reading on the black wire to stator.

Your points are not making clean contact when closed. That's the most common problem I've found for no spark on a bike that has been sitting. They can look clean but have a coating of invisible oxide on them.
1963 YG1-T, 1965 MG1-T, Allstate 250, 1970 CT1b, 1971 R5, 1973 AT3MX, 1974 TS400L, 1975 RD350, 1976 DT175C, 1976 Husqvarna 250CR, 1981 DT175G, 1988 DT50, 1990 "Super" DT50, 1991 RT180, 2017 XT250
27 Nov 2020 16:10 #12

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If its magneto it'll have a reading through the condenser& source coil open or closed from the black wire so long as its disconnected from the loom or the plug coil but the variations is only just readable but a definite difference on an analogue meter if you move it carefully over just opening & just closing. If no difference the often just means dirty points. Sorry i'll go read the story lol then come back incase i'm wrong.
To edit--just thinking back, we never used to unhook from up top. Some models had a wire running off the black that you could hook a points meter or ordinary ohm meter to get the moment of opening. Ignition switch would need to be on so its not shorting the system to earth if you did it that way. Switch shorts the source coil & things to stop the motor. Points check by memory was just a 'very' low resistance meter so needle movement was exaggerated & obvious. Didn't use mine once cdi ignition arrived so it sat for 20 or more before i found it with rotten battery so you can imagine--stuffed.
Last edit: 28 Nov 2020 18:23 by RT325.
27 Nov 2020 17:16 #13

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Thank you all for the help with this. So if I search for 69 yamaha gas I get a bit more info but it is odd that there is such limited info. I will order the puller you listed and make sure everything is cleaned up in there and probably will replace the points and condenser. I will let everyone know the results soon. Any additional information would be appreciated as well. Thanks all
29 Nov 2020 10:00 #14

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You could have bad parts... but if you're not getting a "zero" ohm reading with points closed, that's something you need to figure out... and probably not a defective part issue.

Here's a video on a two methods of determining when the points open... you can see what an ohmmeter does... goes from "0" with points closed to somewhere between"1" and "2" with points open. If you aren't seeing that, you'll never get spark. A solid 1.4 reading sounds like point contacts are not making good electrical contact.




P.S. You don't "gap the points" as an adjustment. You adjust the points to get them to open when the piston is the correct distance BTDC. Setting to 0.016" as you said you did might be a little wide but shouldn't stop it from sparking... I'd use a dial indicator to get timing right or start at 0.014" max gap.
1963 YG1-T, 1965 MG1-T, Allstate 250, 1970 CT1b, 1971 R5, 1973 AT3MX, 1974 TS400L, 1975 RD350, 1976 DT175C, 1976 Husqvarna 250CR, 1981 DT175G, 1988 DT50, 1990 "Super" DT50, 1991 RT180, 2017 XT250
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29 Nov 2020 10:44 #15

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