YD-100 engine backfires and won’t start anymore

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dillon_gard

New Member
Sep 8, 2024
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Hey ya’ll

Was hoping to get some of your input on a problem that just occurred today.

I have a YD-100 motorized bike that I built probably about 7 months ago that has been running fine up until now. I was riding around today and all of a sudden the motor backfired and started to bog down. No amount of throttle input made a difference. I pulled in the clutch and the motor immediately died.

Tried to start it a couple of times to no avail. Every time it would just backfire and bog. This is super surprising because I have never had any engine trouble in the 7 months I’ve had it. It is also completely stock with no carb, filter, or exhaust mods. It’s also got only week old gas in it with some stabilizer.

I haven’t had a chance today to do a run down but I thought I’d get some opinions on here first anyway. Let me know what you think it might be. Thanks.
 
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dillon_gard

New Member
Sep 8, 2024
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A little update for yall,

The spark plug was completely toasted so I replaced it with an E3.32. I also had another stock carb laying around that I decided to put on as a means of eliminating the carb possibility. This carb had been on the bike previously, but got replaced with a new one because the choke lever loosened out of place and got lost on a ride.

The new plug seemed to get it atleast starting, but it is running really rough. It’s definitely got an uneven idle and sputters when revving higher. It doesn’t quite make it to the top of the RPM range.

Maybe the carb switch out was a bad decision? Not really sure what could be wrong, the motor ran fine with this carb on it the last time.

I see a lot of people with similar issues to my original problem talk about the magneto. Any opinions on that?