odd noise

[Slashback115]

(not a technician, so forgive the vocab)

When i get into 3rd gear/40MPH or higher, and i let go of the throttle, my bike starts humming every 2 seconds. pull on throttle and it stops. squeeze the clutch and it stops. I haven't noticed any performance issues. It sounds like its coming from the Engine or exhaust. Any ideas?

My friends say maybe i should clean the carb with seafome

[geezer]

dude your still gonna have to make sence, tech or not. humming? sounds normal to me, my bike does it. im sure its just harmonics and vibration giong throu the frame at a certain frequency :techy:

[Slashback115]

ok... by humming i mean its making a sucking noise.. almost like a hole in a hose sucking in air. I thought maybe it was the tire, but the sound isnt frequent enough

[geezer]

ok now im thinikin air leak in the intake system. get down there with bike running and listen

[tcrave]

You know, I am having a very similar problem. When I am coasting or idling, its fine, but when I am in gear and cruising, it will be normal for a few seconds, then it will have a louder, restrictive sounding hum for a few seconds, then back to normal, then humming and so on. I have no clue what it is either. I didn't post because I wasn't sure how to describe it, but I think I am getting about the same noise you are...kinda like something is rubbing or something. And I did notice oil leaking a little from the air tube going from the air box to the carb (not visible, but there is a yellowish haze all over the engine and the carb, so I know its leaking) so geezer's suggestion may be relevant. Mine does it in all gears, not just 3rd, but I am never really cruising in first and usually not in second either, so I dunno.

[alantf]

...kinda like something is rubbing or something.

I too get this, but it's been doing it for over 4 years now, since the bike was new, & it doesn't seem to have done any harm, so I just ignore it. If anyone knows what it is, though, I might be able to cure it. :2tup:

[geezer]

ok beginners, bikes make all sorts of wierd noises, try riding without a helmet on and youll hear all sorts of scary stuff. but you guys might realy have a problem, but i cant help cause i dont understand, heres a tip. get front wheel off ground spin it check for noise, do rear wheel any noise? get down ther and look

[alantf]

No, it's definitely coming from the engine.

[5th_bike]

Resonance. Mine has it too. Louder-softer with a period of about a second. Like this (OK a little slower): :rawk:

Nothing to be worried about. Just one of the peculiarities of this bike.

[alantf]

No - a definite "rubbing" noise from the engine, like something's too close to the case. Doesn't seem to change with different speeds. Weird O_o