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Motorbike 125cc not running good


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Hello everyone

I have a small 125cc motorbike for the last few months second hand and it has done great, almost 10k miles now

Resently after the cold weather my motorbike is stuttering / bogging and even losing power then throttling

I've oready taken out the Carb and cleaned it the best i could at the time i had (working nights + was midweek)

After cleaning out the bowl, + the jets

The motorbike will now not even start (idle) at all now, it will sometimes fire then die instant with choke and without

After afew days messing about with the carb + getting lack of sleep for my shifts i gave up and brought a new carb off ebay

I installed the new carb, and the motorbike will start / idle, but when i give it some rev's it will bog down then trottle up after 1-2 seconds (on centre stand)

I've let the engine warm up, and i took it out on a ride, and instantly, no power, bogging, stutterin... and it will not allowed me to go passed 30mph without very bad stutterin

Im starting to think fuel filter clog / air filter (box) clog...

*checked / cleaned spark plug, was some carbon deposits but used some sandpaper* *white deposits*

If anything can think of something i've missed please help!!

thanks sonny

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First thing I'd do would be to fit a new spark plug. They can look ok but still fail to produce a good spark. Plugs in bike engines work much harder than in cars so need replacing more frequently.

As said, make, model, year, service history are important to know.

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As [mention]Mississippi Bullfrog[/mention] says, the spark plug can degrade quickly in a short time on bikes. Had the same problem on my ybr, the spark plug died 10 seconds after I have started the engine, looked alright from the outside. Got a new spark plug and it fired up staight away.

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