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78 dt175, wont run after hot


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hi all, i came across a 78 dt175 enduro and the last owner said it would glug after

riding it for a while, die, then wouldnt start again til it cooled down. bike isnt running at all currently and

he said thats what happened the last time he rode it then it never started again, i cleaned the carb one day and got it started, then it died. im going to screw with it a bit more and try to get it at least running. any suggestions on what to do after i get it running to fix the drops when its hot problem?

also just another little thing, i guess the bike was running with no battery, as far as i can tell anyway.

the thing is, there are no battery connections in the wiring harness, where do they usually come from, i will be trying to run it with a battery again so i can make it street legal.

thanks for any help you might have!

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thanks a lot jason, i appreciate it! i dont have the finances to pick up a shop manual just yet so any help you have is awesome.

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There should be a red wire with a connector on it near the cdi, that doesent go to the cdi. Not to be confused with the red on the 7 wire cdi set up don't connect that to the battery.

The - or black wire may have broken away it connects to the chassis using the voltage regulator retaining bolt on the later models.

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natedogg,

Try some anti-seize lubricant on your spark plug and see if that helps the hard start when the bike is hot. I have the same bike as you and had the exact same problem. On a cool morning it would be a first or second kick starter. If I ran a few errands around town it would get progressively harder to start and once hot wouldn't start at all, but a new spark plug would make it start right up despite the old plug looking perfect.

I used Permatex Anti-Seize for a $1.99 solution and my bike is almost always a first kick starter now at any temp. Just use a dab though on the middle threads. Hope that works.

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thanks man im gonna try that as soon as i get it running.

the current problem is that the new carb i bought has a piece that i dont know the name of thats usually on the throttle cable going into the top of the carb actually mounted on the carb so i got the cable stuck in the old one trying to drunkenly manhandle it after a night at the bar. i know this sounds dumb and it is, anybody know an online store that sells a throttle cable for the 78dt15? or another one that will fit?

ill be posting pictures in the next few days so you guys can see whats going on.

and i think the bike was rewired for no battery... this might sound stupid but is there some way that the lights could be working without a battery, obviously when running, but is that possible? it just seems stupid to me that someone would go through all the trouble of rewiring all that but not take the time to unbolt the headlight ears or take of the one bolt that keeps the blinkers on...?

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Powersportsplus.com has the best prices I've found on the web for OEM. Sometimes shipping is fast, sometimes slow but customer service has always been awesome if I want to add or change something on an order. Here's a link to their parts list for cables. http://www.powersportsplus.com/parts/search/Yamaha/Motorcycle/1978/DT175E/HANDLE+-+WIRE/parts.html

I tried an aftermarket throttle cable for my bike and it was unusable garbage. I ordered a new OEM throttle cable from the above that I'm going to install next week.

Your bike is wired from the factory to run the headlight only when the engine is running. Signals and instrument lights are on the battery.

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if u lift your tank off their should be a rectifier with a red wire and a double white wire connected to it, it mite be somewere else on your bike mine is an 81 but id say their similar on mine its bolted to the frame under the tank next to the indicator flasher relay,the red wire on that should go back towards the battery and that should be your + and your black - will be next to your voltage regulator thats the little silver box with a single yellow wire you can use the earth next to that as your - black wire.im at the wiring on mine al day trying to follow lines tru the manual and this seems to be the way mine is going to work out

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hi all, i came across a 78 dt175 enduro and the last owner said it would glug after

riding it for a while, die, then wouldnt start again til it cooled down. bike isnt running at all currently and

he said thats what happened the last time he rode it then it never started again, i cleaned the carb one day and got it started, then it died. im going to screw with it a bit more and try to get it at least running. any suggestions on what to do after i get it running to fix the drops when its hot problem?

also just another little thing, i guess the bike was running with no battery, as far as i can tell anyway.

the thing is, there are no battery connections in the wiring harness, where do they usually come from, i will be trying to run it with a battery again so i can make it street legal.

thanks for any help you might have!

I have a '78 DT175, and the battery connections should be underneath the air cleaner rubber. There should be a red wire with a clear plastic fuse box connected to the harness at one end and the + terminal of the battery at the other. Should also be a double black lead for the - terminal same place.

As for the not running issue IMHO a carb disassemble would seem in order just so you know what you got, unless that's what you mean when you say you cleaned it. Wasn't till the 3rd cleaning on mine before I got all the air holes unplugged on the main nozzle. If the float sticks to the closed side and fuel doesn't get to the float bowl it will die, same thing if the breather hose to the fuel cap is clogged.

When it dies is it sudden, or does it gradually bog and then die?

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  • 3 weeks later...

Might be a failing source coil winding for the cdi, its a classic symptom. Pull the rotor and carefully heat it with a hot air gun and watch the resistance, if it suddenly drops or changes its faulty. It will gradually incresase with no sudden change if its ok.

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