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TOPIC: Restoratin engine start troubleshooting

Restoratin engine start troubleshooting 27 May 2019 14:50 #1

  • DreddwardElric
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So I've got all the accessories working, lights, horn, etc. The fuel tank is plugged in, air filter installed, new spark plug in, she should be ready to start. Thing is, she doesn't.

I tested the old ignition coil and the secondary reading was junk. So i ordered a new one online. With the old or new coil, it won't fire. Is there some other areas i should be checking? I have the neutral light working so i know when I'm in neutral to start. Any suggestions?

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Last Edit: by DreddwardElric. Reason: Misspelling

Restoratin engine start troubleshooting 27 May 2019 16:36 #2

  • DEET
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You might get more help if you were to post what bike you are talking about.
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Yamaha@nc.rr.com

Where the Yamaha Enduro is still a current model...

Restoratin engine start troubleshooting 27 May 2019 17:04 #3

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Right, sorry. It's a 1978 DT 175.

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Restoratin engine start troubleshooting 27 May 2019 17:13 #4

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First thing I'd check is that the handlebar switch on the right side next to throttle is "on" and not shorted out.

It's also not unheard of for "coil bought online" to be bad...

Stock ignition coils on that model are pretty reliable.

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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

Restoratin engine start troubleshooting 27 May 2019 17:59 #5

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"78 looks CDI which opens a can of worms But if you unplug the ignition switch--plus the kill switch too then that'll eliminate any possible faults in that area as the switch/kill switch just short out the source coil to earth to kill it--think i'm right!! he said hopefully. Just trying to keep it simple for a start. Was it running prior to dismantling. No wires pinched coming away from the mag etc.
www.partzilla.com/catalog/yamaha/motorcy...dt175e/c-d-i-magneto

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Restoratin engine start troubleshooting 27 May 2019 20:42 #6

  • DreddwardElric
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I thought about the switch when I was eating dinner. I took the switch assembly apart, cleaned the contacts, and will try it tomorrow.

I'm just going to say here again, I know NOTHING about engines of any kind. I know what parts are, and what SOME of them do. So what's coming now is probably going to sound really dumb.

I haven't had the lower part of the engine/crankcase open. Could something be wrong with the magneto or something that will cause me to not have spark? How do I know the CDI is functional? I've pretty much ruled out any wiring harness issues, as I've cut the wrap off and traced every wire to its home. In some cases, I've cut the ancient connectors off and joined wire to wire (temporarily) just to ensure that old connectors aren't the issue.

I will say, the lights didn't work and stuff until I pulled the regulator off and cleaned the surface of it, the wire connectors, and the ground wire connector. Could I be missing something simple like that which could potentially not allow the spark plug to get spark.

Also, when I push the kick starter down, I don't give a stroke until it engages, which only happens like halfway through the total pedal travel. It seems pretty long before I feel resistance, is that normal?

I know it can be frustrating to guide someone through that knows so little, but I really appreciate it. There is a startling lack of video tutorials and explanations for older bikes on Youtube, etc.

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Restoratin engine start troubleshooting 27 May 2019 20:46 #7

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Also, another weird thing I just remembered. The top mounting hole thing for the ignition coil fell off. I've still been putting that ground wire on the bottom one and just zip-tying the coil in place for now. Does it need metal contact on both mounting holes on the coil for some reason?

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Restoratin engine start troubleshooting 28 May 2019 05:19 #8

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Earthing the coil is only needed by one end of the plug coil. Zip tying it to the frame isn't ideal but so long as an earth wire is to one end it'll be good. You're working things out as you go so far as understanding it goes, that's good. A simple test of the stator source coil would be to check with an ohm meter & i'd expect around 350 ohms from the Black with Red tracer to earth. If it's not that type it'll have a red wire plus a brown wire, so test between them & not sure of the reading but i'd guess more than 350. At this stage i'd be more looking for an open circuit like a break in the windings internaly rather than a specific reading. The trigger will be White with Red Tracer & guessing around 100 ohms. [just not open circuit at least. You could, if you wanted, short circuit all the wiring & just follow the stator direct to the cdi box. Forget the lighting colors. Just Red, Brown, & White/red also a black straight to the box. Then Orange from the box direct to the plug coil. Don't worry about whatever color's on the coil as only one wire in & orange goes to that. Black/white tracer is a kill wire so leave that unhooked or could if ya want to hook it to a kill switch or just get ready to short it if say the throttle is stuck. Anyway, now i've confuse everyone, i hope you can sift through it all & hope someone puts me right as been a many years since working on one of these.
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Restoratin engine start troubleshooting 02 Jun 2019 12:22 #9

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Hey, friends!

I'm back! I looked at the wiring from the mag to the CDI and just cut off all of the old bullet connectors and hard wired everything together. I HAVE SPARK!

However, I still am unable to start the motor. I don't get even a hint of ignition. I hear the piston run through its travel, I smell the gas being dispensed, but no ignition. I don't know if it's just that the spark is weak, but it seemed like a lil spark about the size of what I, a newbie, would expect a plug to make. I also broke 1st and 2nd free and attempted to roll start the bike. Any ideas on what my issue might be or some methods I could use to diagnose it?

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Restoratin engine start troubleshooting 02 Jun 2019 16:42 #10

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does the motor have a belly full of fuel & needs a push around the yard or a tow down the road. Just be sure the throttle is shutting right off if you contemplate either of those options. Have a plan A & B incase it runs away. Click click throttle hitting bottom with idle speed screw backed off etc.
I may have mentioned the flywheel locating key previously as timing will be lost if damaged but in saying that i'd think it'd at least fart, or even explode & try to blow the exhaust off, well it would on a slip on pipe not a bolt on type/

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