periodic thumping sound...

My bike has this periodic thumping sound when accelerating, but not when decelerating. The frequency increases with vehicle speed. Any idea what could be the cause, and/or if this is "normal"?

Could be a slight miss in one of the cylinders to having a rod about to let go.

If you got a carb thats a little plugged then as you accelerate it would feel like a thump more so at low speeds. A rod end would be about the same and more of a metal banging sound and be all the time. Carb might be intermitent. If your not sure it could be well worth taking it in.

Or WHat I would do is get a long shaft screwdriver and use it like a stethascope, put it on the engine and one end on your ear and have a friend rev it a bit.....If you have to ask which end to put in your ear ....take the bike to Bill or Ted!!

Quote:

Originally Posted by UltraMax

My bike has this periodic thumping sound when accelerating, but not when decelerating. The frequency increases with vehicle speed. Any idea what could be the cause, and/or if this is "normal"?

Take a close look at your chain and see if there are any stiff links / kinks in it. Could also be a tire problem, but not very likely.



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Turns out to be chain... After I lubed it, in the next ride no more noise. I never dreamed it's the chain... I didn't think the chain would make that big of a noise. Probably should've lubed the chain right after I rode in rain. Oh well lesson learned! Thanks for the help guys.