After hitting a nasty bump on the road a month ago, which stalled my bike immediately, the engine will occasionally go from providing normal amounts of power to about 25% of that power, and it will stay in that low power state for a seemingly random amount of time, could be 30 seconds could be 10 minutes. The engine will make a deeper noise when it knocks into that state, and it will have to rev to 4-5k RPM to get moving to 10 mph, normally something it could do with 1-2k rpm. Basically making it slow as hell and unridable when it gets like this.

It used to happen once a week, then once a day, now the bike cannot even get down the street without running into this low power state. It consistently happens when stopped at a light or going down a steep hill.

I know the problem was caused by the bump but I don't know what it did. I replaced the spark plugs, recently cleaned out the air filter, exhaust is coming from both pipes when it's like this so both cylinders should be firing. My bike is carbureted and google searches are leading me to believe there might be a problem there, but I have never pulled carbs before and am not sure what mess I'd be getting into. A couple days ago I sat on my bike to try to figure this out and the headlight and taillight wouldn't turn on, so there is probably a wiring issue somewhere. Could that be related to this low power problem?

Looking for guidance on what part / area of the bike I should be troubleshooting to narrow it down. Does it sound like a carb problem? Electrical? What can I do to eliminate some potential causes?

thanks 1980 gs250t

  • Welcome to Motor Vehicle Maintenance & Repair! Commented Sep 23, 2019 at 21:54

1 Answer 1


I would check your fuel line. If it cuts out on you like that then its either lack of air, fuel, or spark, right? First I'd check the fuel line and then I'd examine the petcock mechanism. Id definitely start there before embarking on a carb rebuild. That being said, depending on the last time they were cleaned it might not hurt.
First things first, start with the fuel delivery system. Also double check your tank vent and make sure it's not clogged. Hope that helps

  • Had a similar issue once with a carb motorcycle after hitting a bump the rubber mixture intake pipe connecting the carb to the engine(being dry and less elastic due to age) got a crack and additional air messed up the mixture...
    – kokobill
    Commented Nov 11, 2019 at 14:02

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