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WR Chirping

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Posted by: YZ__rider---------------------

I recently bought an 01 WR426. The bike is super clean...it passes all of the basic tests...very little peg and rotor wear (stock parts), wheel bearings are solid, no leaks of any kind, no smoke, etc. However, it has a chirp during accelleration. A guy here at work that has been riding offroad for around 40 years suggested that it is air flow into the carb, is that true? I have never heard of this issue. It has the air box cover removed and the exhaust has been opened up.

I searched the forum and found very little information on this topic.


Posted by: YZ__rider---------------------

Somebody has go to know something about this odd chirping noise.

Rich?


Posted by: Rich Rohrich---------------------

I have no idea what you are talking about. None of the YZF or WRF engines I've dealt with ever made a "chirping noise", but then again "it has a chirp during acceleration" is pretty vague.


Posted by: YZ__rider---------------------

I would agree, it is vague, but I dont know how else to describe it. I found one thread on this site by searching "chirping" that discusses air flow into the carb causing a high pitched sound during accelleration. Also, the guy I ride with here at work is quite experienced and he said it was air flow, but I dont understand how air flow can make a noise.


Posted by: ellandoh---------------------

i guess if you can whistle dixie you can see how air flow can make a noise


Posted by: Rich Rohrich---------------------

Quote:
Originally Posted by YZ__rider
but I dont understand how air flow can make a noise.


Stand next to someone running an airflow test on a flow bench and you'll get a real aural education.




Posted by: BSWIFT---------------------

Is this "chirp" constant, steady, regular, increasing or decreasing in intensity or just once? Does it occur only when you are riding or does it make the "chirp" when you blip the throttle? Are you sure it is coming from the engine or could it be the transmission or drive gear/clutch, etc.
If there were some unusual wear in the suspension, upon hard acceleration the front forks will extend to the max, that instantaneous slamming of the parts "could" cause a chirp. It would be irregular and occur only when the suspension is fully extended. Hopefully, you can discribe the occurance with a bit more detail.
Also, is it a high or low pitch?


Posted by: YZ__rider---------------------

Rich
I have never stood next to a flow bench...what type of noise does it make? I dont have access to one....as most wouldnt I assume.

BSwift
The noise couldnt be the transmission or suspension because it will make the same sound sitting still and 'bliping' the throttle and only for a fraction of a second. It is a very high pitched sound. I dont belive that it could be anything resulting from excessive wear because the bike appears to have very low milage. I guess I will assume it is air flow and ride it...however, it is slightly annoying. Perhaps I should install the air box cover to limit the air flow as a short term test.


Posted by: BSWIFT---------------------

OK, I've got no idea. If it is instantaneous, Rich's suggestion makes sense. I've never heard the sounds from a flow bench test.
Got a stethoscope? Might be able to isolate what part of the engine that the chirp is coming from.


Posted by: YZ__rider---------------------

I dont have a stethoscope, so it is difficult to pinpoint exactly where it is coming from. From the feedback here, I am assuming it is air flow.


Posted by: Rich Rohrich---------------------

On the flow bench you'll hear high frequency whistling sounds, but that's with a lot of air moving. If you hear it just blipping the throttle, you can probably count on it NOT being air flow. There is very little air movement blipping the throttle with no load while it's sitting on the stand.

You need to keep looking.


Posted by: ellandoh---------------------

you dont necessarily need a stethoscope, ive used a 3' piece of garden hose to zero in on a noise on many occasions


Posted by: BSWIFT---------------------

Quote:
Originally Posted by ellandoh
you dont necessarily need a stethoscope, ive used a 3' piece of garden hose to zero in on a noise on many occasions
I've used a long screwdriver to do the same thing.



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