qt50 pro...

i have a qt50 79 model and it ran last summer but the carb needed cleaning so i got it cleaned and it also needed a new spark plug so i got 5 and now it wont get spark not even aweek one i got anew coil sitll dont work i rewired it like 3 different time and still no spark i used this wireing digram


Re: qt50 pro...

Ben Van Zoest /

Any corrosive joint or bulb sockets?

Re: qt50 pro...

ryan winter /

no none once so ever do they just go bad or can i fix it is their a different wiring digram

Re: qt50 pro...


i own 4 qt's. don't quit on this bike.

there is a possibility that the CDI unit is blown. also, that start/run key switch can be deceptive. i don't own any with that type of switch, but i have a close friend with one and i have done a considerable amount of work on it. you can see the spark on the start position, but when you switch to run, you cant see it any more. i was really tired and didn't want to work on it any more, so i just put it together and tried it. it ran. you might not see the spark in the run position, but it's there. i have never experienced anything like it before.

Re: qt50 pro...

Luke Evans /

clean up all the electrical connections with a bit of emery cloth


Re: qt50 pro...

If that wiring diagram is close to your bike's, try disconnecting the engine Stop-switch wire..

If any part of this wire or if anything connected to it is grounded, there can be no spark. A bad switch, a worn section of wire insulation somewhere in the harness, a wrong connection, or a number of other things might ground that kill-circuit.

See attached pic.

I would disconnect it as close to the magneto as is possible and then test for spark. If you then do get a spark you'll have to go through all the wiring and find the fault.


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