Alarming noise


10 replies to this topic
  • DannyChaos

Posted June 27, 2014 - 07:35 PM

#1

Only happens when in motion.
Doesn't seem to be at any particular speed or in any particular gear.
I know for a fact it has happened in forth at cruising speed 45-40.
Sounds like if you disconnected the low pitch horn on a car, leaving only the high pitch horn and gave it a quick beep.
There is no change in power or handling at the time of the noise. It's pretty damn loud because I can hear it clear in my helmet. I have not heard it under full acceleration or just putting along, so I'm assuming it's happening about mid range RPM's mid range throttle. All fluid levels are where they should be and bike is running pretty damn good.
Gotta be bearing or something rotating. Brakes, sprocket??
Really hoping it's not coming out of the motor! ? I can't get it to repeat once it happens. So I can't pin point it. It scares ya though. Enough to chop the throttle then it's gone
Did lots of searches and can't seem to find anything like this.

  • Krannie McKranface

Posted June 28, 2014 - 07:04 AM

#2

Bike

Year

Hours

Tuning

Last top end job



  • DannyChaos

Posted June 28, 2014 - 07:29 AM

#3

99wr400f
do not know total hrs
Jetted, hotcams intake and exhaust with auto decomp.fmf powercore , airbox mod, twin air filter,
Top end rebuilt last fall with very little riding done since. I did not rebuild the top end. It was done by the prior owner and I was given paperwork and receipts.
Bike starts first or second kick and runs strong other than a slight off idle studded in the throttle every now and then.
My buddy was riding with me and said he could hear it. Like a moped horn beep

  • DannyChaos

Posted June 28, 2014 - 09:53 AM

#4

just took the bike out again to try and catch the sound on my GoPro. Unfortunately the camera was not able to pick up the sound but I am now able to get the bike to make the noise pretty much on demand. Seems to happen at around 43 miles per hour. I have been able to get it to make the noise in both 3rd gear and forth. Just cruising, staying even on the throttle, just shy of midway through the rpm range the sound comes out of nowhere.

  • DannyChaos

Posted June 28, 2014 - 12:18 PM

#5

Best I could get. Sounds like a train whistle.

Edited by DannyChaos, June 28, 2014 - 12:23 PM.


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  • still2smokin

Posted June 28, 2014 - 03:55 PM

#6

I would check for loose spokes.

 

As well as....... check out the speedo cable and hub housing , worn chain/sprockets, warped rotors etc.

 

Maybe give everything a greasing .



  • DannyChaos

Posted June 28, 2014 - 04:35 PM

#7

http://scontent-b.cd...661135580_n.mp4  

 

 

You can hear what I'm talking about here.

Roughly 35-37mph in 3rd gear just shy of half throttle midway through the rpms crusin.

Any more throttle and the sound cuts out,any less and it cuts out.

I have heard it in 4th as well in just about the same rpm /throttle range.

Sprockets are good,bearings are all new in the rear and spin free and quiet with no play up front. I have not come across any loose spokes but now that you mention it,my front rotor is a bit warped. I'll pull the caliper and zip tie it out of the way for my next test ride. I have not heard this noise while costing though,so that leads me to believe its rpm related.


Edited by DannyChaos, June 28, 2014 - 04:45 PM.


  • still2smokin

Posted June 28, 2014 - 05:44 PM

#8

maybe see if you can isolate by dragging the front or rear brake at that speed .

 

Do you have a metal skid plate ? maybe that's vibrating.

 

I once had a spoke that seem tight but was actually bottomed out and vibrated a little at the hub .

 

Hard to hear the noise , but if it only happens at a specific mph I would focus on the wheels first .



  • Krannie McKranface

Posted June 28, 2014 - 05:45 PM

#9

I heard it.

It does sound like a resonance, not a friction 'squeal'. 



  • DannyChaos

Posted June 28, 2014 - 06:31 PM

#10

I'll pull the skid plates and front break tomorrow. I'd love for it to be that easy. I just wanna ride this damn thing.lol

  • DannyChaos

Posted June 29, 2014 - 10:19 AM

#11

Facepalm....
Skidplate the whole time




 
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