Noticeable knocking sound...

[Raffi]

Got my first bike about a month ago now, 2014 Scrambler 900, bought it used from a dealer just north of San Francisco. I pretty immediately noticed a sound that is concerning that I was hoping someone might have some insight into.

When accelerating, especially in 1st, 2nd and 3rd, there is a noticeable knocking sound, like a wooden mallet or wooden baseball bat. Having trouble determining exactly where it's coming from, but it seems to increase in speed as I accelerate, however I don't believe it gets faster as I'm traveling faster, seems to have more to do with RPM- when I upshift, the tempo of the knocking is slower and then speeds up, which suggests to me it's tied to the tranny. Also, I can feel a "grinding" vibration through the pegs that I feel is tied to it, though I can't be sure.

It does not occur when traveling steadily at any speed, only when putting the bike under load during acceleration.

This sound familiar to anyone?

I do have a 90-day warranty on it (that I may extend) and have spoken with the dealer who did say he'd take a look at it. At this point it's just a timing thing, waiting for my Jeep to get back from some repairs I'm having done to it. My concern is that I'm causing more damage by riding it in the meantime.

Any insight is appreciated!

 

[Qship]

I would get that looked at ASAP. Does not sound good from what you describe. Buying used, you never know how the previous owner treated it.

 

[shanered6]

It sounds like eather the out put shaft bearing ( front sprocket shaft bearing ) or it could be the clutch shaft bearing ? ... but before all that check your chain alinment as if its way out it will cause the same kind of symptoms .

 

[Raffi]

It sounds like eather the out put shaft bearing ( front sprocket shaft bearing ) or it could be the clutch shaft bearing ? ... but before all that check your chain alinment as if its way out it will cause the same kind of symptoms .

Thanks for the tip. It'd be great if it were the chain, but I'm afraid it's more in the realm of the first two possibilities, considering how it's behaving... I've got a week or so more of riding before I get my other wheels back, so hopefully it doesn't get worse in that time.

 

[Qship]

A worn or improperly adjusted chain can also contribute to the noises like you described as shanered6 mentioned. If it's not lubricated properly and has elongated(stretched) and the sprockets are worn it will make some strange crunching/grinding noises as it turns.
How many miles on your bike and does the chain look lubricated/cleaned. There are many videos on how to check and maintain your bike chain if you are not too familiar with it.
Not trying to be insulting or anything disrespectful, just don't know your level of mechanical knowledge when it comes to bikes and in particular, chains and sprockets.
Check out this You Tube vid to see if it helps;
View: https://www.youtube.com/watch?v=xQz2kIiJZ6k

 

[Raffi]

A worn or improperly adjusted chain can also contribute to the noises like you described as shanered6 mentioned. If it's not lubricated properly and has elongated(stretched) and the sprockets are worn it will make some strange crunching/grinding noises as it turns.
How many miles on your bike and does the chain look lubricated/cleaned. There are many videos on how to check and maintain your bike chain if you are not too familiar with it.
Not trying to be insulting or anything disrespectful, just don't know your level of mechanical knowledge when it comes to bikes and in particular, chains and sprockets.
Check out this You Tube vid to see if it helps;
View: https://www.youtube.com/watch?v=xQz2kIiJZ6k

Not at all, appreciate the suggestions- and the video! A good amount of automotive know how but none specific to bikes so I’m definitely open. I’ll take a closer look at the chain and see if I notice anything. Thank you!