Author Topic: Odd buzzing sound at 3k rpm. Any thoughts?  (Read 612 times)

Offline mr_pacman

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Odd buzzing sound at 3k rpm. Any thoughts?
« on: June 12, 2021, 05:13:27 PM »
Looking for some guidance on this odd noise that started happening.

Bike is a 2014 V7 Racer with 2,300 KM's. I bought the bike with 1,900km's.  With the exception of an Agostini exhaust , the bike is bone stock.

I didn't notice this problem for the first 200km that I rode it (but it may have been there) and did notice it the last 200km which is after I had the following service work done:

- Change Engine oil and filter
- Change gearbox oil
- Change rear drive oil
- Change spark plugs
- Adjust valves
- remove fuel tank and change fuel filter

Here is what's happening:

- Under load while acceleration in any gear, I get  a buzzing sound right at 3k rpm.  It sounds like a buzzing bee.  It seems to be coming from the engine (perhaps the right hand side but that could be my imagination). It's not there at 2k rpm and goes away at 3,500 rpm.  It doesn't seem to happen on deceleration but that's hard to tell as it passes through that rev range quite quickly.

- It doesn't appear to happen in neutral when I rev the bike and leave it at 3k rpm. At least I can't hear it and I suspect I would be able to without a helmet on. So, let's assume it's not happening in neutral at a stand still.

- checked all the frame bolts and nothing appears to be loose at all.

- I've also noticed that when going up a steep hill, if the engine is lugging a bit, and I open up the throttle, the sounds starts a bit earlier and continues on past 3k rpm. It's not the exact same buzzing sound, but it's a similar sound. Not sure if this is related or not.

So, if we assume this started happening after the recent service work I had done, is there anything in that list of work that could cause a sound like this?  I can't really think of anything that would make this sound right at 3k rpm.

If the answer is no, any thoughts on what could be causing this sound? 

Any thoughts would be appreciated

James


« Last Edit: June 12, 2021, 05:16:22 PM by mr_pacman »

Offline Kiwi_Roy

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Re: Odd buzzing sound at 3k rpm. Any thoughts?
« Reply #1 on: June 12, 2021, 05:31:51 PM »
It's something loose and may not be related to the engine, I started getting something similar on my V7 III, turned out to be the flyscreen tapping on a nearby bolt.
I moved the headlight bracket a short way on the fork tube, that cured it.
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Offline Chuck in Indiana

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Re: Odd buzzing sound at 3k rpm. Any thoughts?
« Reply #2 on: June 12, 2021, 07:26:03 PM »
Yeah, it's vibration related. Keep looking around.. you'll find it. I chased a vibration through tear downs, balancing, etc. and it was a tweaked crash bar. :rolleyes:
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Offline slowmover

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Re: Odd buzzing sound at 3k rpm. Any thoughts?
« Reply #3 on: June 12, 2021, 07:38:10 PM »
I had the same problem. It was the ring around the headlight.Ran teflon tape around it and that settled it. Do a search here and you’ll see other causes.

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Re: Odd buzzing sound at 3k rpm. Any thoughts?
« Reply #3 on: June 12, 2021, 07:38:10 PM »

Offline mr_pacman

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Re: Odd buzzing sound at 3k rpm. Any thoughts?
« Reply #4 on: June 12, 2021, 10:26:55 PM »
Thanks for the replies. 

It really does sound like it's coming from the right hand side of the engine at 3k rpm under load.

Is it possible for the engine to make this sound at 3k rpm under load but not at any other RPM and not at 3k rpm while in neutral revving the engine? While it seems unlikely to me, I just wanted to get the opinion of you experts.

I've checked every bolt that I can access without taking the fuel tank off.  Checked the headlight and exhaust.

Any other thoughts?

Offline sign216

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Re: Odd buzzing sound at 3k rpm. Any thoughts?
« Reply #5 on: June 13, 2021, 06:16:12 AM »
Keep checking.  It's probably an odd little thing, and maybe peculiar to your bike.

For example, I get a buzzing sound on my V7 Classic, from ... of all things ... the clear lens on the license plate light.  The lens is loose in the holder.  Noticeable only in neutral. It's on my long list of "must fix."

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Offline blu guzz

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Re: Odd buzzing sound at 3k rpm. Any thoughts?
« Reply #6 on: June 13, 2021, 06:35:31 AM »
i have a v85, but will get that kind of noise from a bash guard under the right exhaust pipe if i accelerate a certain way.  it's tight but just the resonance causing the noise.
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Offline John Warner

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Odd buzzing sound at 3k rpm. Any thoughts?
« Reply #7 on: June 13, 2021, 06:54:32 AM »
Very common on Singles & Twins.

Stelvios are prone to it if a Stone gets trapped between the Sump and the Bash-Plate, if the Engine Bars aren't done up really tight, or if the Cylinder Mounting Plate Bolts are loose.

Keep looking as others have said, pay particular attention to anything made of sheet metal.
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Offline Chethro

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Re: Odd buzzing sound at 3k rpm. Any thoughts?
« Reply #8 on: June 13, 2021, 07:42:37 AM »
On my V7III the header shields on the horizontal runs under the engine would get loose and vibrate. I'm not sure if you have those or not. On my V85TT, the header shields on the sides vibrate/buzz badly under hard acceleration.
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Online Huzo

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Re: Odd buzzing sound at 3k rpm. Any thoughts?
« Reply #9 on: June 13, 2021, 08:43:52 AM »
I noticed an intermittent rattle starting in my Norge a long while back.
Was convinced something was about to come through the side. Turns out it was the left header touching the centrestand pivot bolt.
Swung the pipe out 5 mm and the thing sounds better than it did at 50,000 k...(it’s done just on 200,000..)

Offline Cam3512

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Re: Odd buzzing sound at 3k rpm. Any thoughts?
« Reply #10 on: June 13, 2021, 06:40:30 PM »
i have a v85, but will get that kind of noise from a bash guard under the right exhaust pipe if i accelerate a certain way.  it's tight but just the resonance causing the noise.

I chased an identical vibration exactly and only at 32-3500 RPM’’s on my V85.  Started happening AFTER I installed the Y-pipe, so I knew it had to be associated.  One day I was determined to find the cause.  I took off the bash plate, still there. Took off the header shields, and it was gone!  Saw a small mark on the inside of the left shield (I Cerakoted the bash plate and shields black).  Turns out the head of the exhaust clamp nut was making contact with the shield and only got audible at certain RPM’s.  Many said “they all do that”, but I didn’t buy it.  It was driving me nuts!

My guess is yours is associated with the tank being off.  I would start there.
« Last Edit: June 13, 2021, 06:43:42 PM by Cam3512 »
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Offline mr_pacman

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Re: Odd buzzing sound at 3k rpm. Any thoughts?
« Reply #11 on: June 13, 2021, 07:29:18 PM »
I chased an identical vibration exactly and only at 32-3500 RPM’’s on my V85.  Started happening AFTER I installed the Y-pipe, so I knew it had to be associated.  One day I was determined to find the cause.  I took off the bash plate, still there. Took off the header shields, and it was gone!  Saw a small mark on the inside of the left shield (I Cerakoted the bash plate and shields black).  Turns out the head of the exhaust clamp nut was making contact with the shield and only got audible at certain RPM’s.  Many said “they all do that”, but I didn’t buy it.  It was driving me nuts!

My guess is yours is associated with the tank being off.  I would start there.

I spent 2 hours today going through the bike trying to track down this sound. I didn't consider that it could have been when we took the tank off. I have a friend coming over this week to remap our ECU's with Beetle maps so I'll see if he has time to help me take off the tank, and perhaps see if that could be causing it.

Thanks for the suggestion. Hopefully it is the tank as I suspect it's more of an annoying sound vs the engine about to grenade which is my main concern .
« Last Edit: June 13, 2021, 07:29:53 PM by mr_pacman »

Offline Cam3512

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Re: Odd buzzing sound at 3k rpm. Any thoughts?
« Reply #12 on: June 13, 2021, 07:34:34 PM »
I spent 2 hours today going through the bike trying to track down this sound. I didn't consider that it could have been when we took the tank off. I have a friend coming over this week to remap our ECU's with Beetle maps so I'll see if he has time to help me take off the tank, and perhaps see if that could be causing it.

Thanks for the suggestion. Hopefully it is the tank as I suspect it's more of an annoying sound vs the engine about to grenade which is my main concern .

When the tank is off, make sure the bolts that hold the two rubber pucks where the front of the tank sits haven’t vibrated out.  If gone unchecked, they will vibrate against the inside of the tank and eventually wear a hole clean through.  Regardless, add some locktite to their threads.
« Last Edit: June 13, 2021, 07:44:33 PM by Cam3512 »
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Offline mr_pacman

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Re: Odd buzzing sound at 3k rpm. Any thoughts?
« Reply #13 on: June 13, 2021, 07:43:50 PM »
When the tank is off, make sure the bolts that hold the two rubber pucks where the tank sits haven’t vibrated out.  If gone unchecked, they will vibrate against the tank and eventually wear a hole clean through.  Regardless, add some locktite to their threads.

Are those the two pucks that are in a vertical position and a hard plastic/rubber or the smaller ones that lay flat under the tank and are almost like a thick washer?

Offline Cam3512

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Re: Odd buzzing sound at 3k rpm. Any thoughts?
« Reply #14 on: June 13, 2021, 07:45:57 PM »
Are those the two pucks that are in a vertical position and a hard plastic/rubber or the smaller ones that lay flat under the tank and are almost like a thick washer?

The two vertical ones where the grooves on the front of the tank sits.
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Offline mr_pacman

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Offline Cam3512

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Re: Odd buzzing sound at 3k rpm. Any thoughts?
« Reply #16 on: June 13, 2021, 07:50:50 PM »

Location #14 in this link?

https://www.parts-motoguzzi.com/moto-guzzi-motorcycles/750-MOTO-GUZZI-MOTORCYCLES/V7/2016/V7-II-Stone-ABS/FRAME/Frame-I/457/12/1193002142/1112

Yes.  And #12 are the bolts you should check for tightness and Locktite.

It’s been years since I did it on my now gone ‘14 Special, but if I remember correctly you don’t have to disconnect the pump and remove the tank entirely.  Take the seat off and remove the rear tank bolt.  Then lift and slide the tank back far enough exposing those rubber pucks. 
« Last Edit: June 13, 2021, 08:23:44 PM by Cam3512 »
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Offline mr_pacman

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Re: Odd buzzing sound at 3k rpm. Any thoughts?
« Reply #17 on: June 13, 2021, 11:30:00 PM »
Yes.  And #12 are the bolts you should check for tightness and Locktite.

It’s been years since I did it on my now gone ‘14 Special, but if I remember correctly you don’t have to disconnect the pump and remove the tank entirely.  Take the seat off and remove the rear tank bolt.  Then lift and slide the tank back far enough exposing those rubber pucks.

I took the bike out tonight and noticed the sound between 1,500 rpm and 4,000 rpm. Couldn't get it to replicate on demand but it was there. Sounds more like a scraping sound and it's around the tank/motor area.

As soon as I heard it, I pulled the clutch in and held RPM's and it continued for a few seconds (hard to keep it at those revs while coasting along the street with the clutch in) so I don't think it's transmission related.

I'll burn some gas off and pull off the tank and see what I can find.  I'm hoping I can do it without disconnecting the fuel line. I'll also check the bolts on the cover that was removed to install the new fuel filter. I suspect if those were loose I would be leaking gasoline and would know there was a problem.
« Last Edit: June 13, 2021, 11:41:38 PM by mr_pacman »

Online reidy

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Re: Odd buzzing sound at 3k rpm. Any thoughts?
« Reply #18 on: June 14, 2021, 03:23:02 AM »
I had a similar sound a few years ago on a Nevada. It turned out that at certain revs and power settings the side spring would resonate enough to just make contact with the exhaust. If your spring is close to the exhaust it could be it. It started after a tyre change as the exhaust went on at a very slight different angle. 

I have not done a gearbox oil change on your model. On the Nevarda the exhaust cross tube was close to the gearbox drain. It was recommended to me to wrap the exhaust in aluminum foil to stop oil getting on it. Apparently some remove the balance pipe for the gearbox oil change.

 
« Last Edit: June 14, 2021, 03:26:22 AM by reidy »

Offline chuck peterson

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Re: Odd buzzing sound at 3k rpm. Any thoughts?
« Reply #19 on: June 14, 2021, 07:03:26 AM »
2007 Nevada

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The one hidden in back broke making a buzz
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Offline mr_pacman

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Re: Odd buzzing sound at 3k rpm. Any thoughts?
« Reply #20 on: June 14, 2021, 08:20:44 AM »
I just noticed something. if you are at the front of the bike looking at the headlight, there are 2 screws. One on the left side and one on the bottom.  Looking at the gap in the headlight, these screws go into some type of spring.

The bottom screw is very tight.  The screw on the left has play. Enough that I can get my fingernail under there and move it in and out maybe 1/2mm or less.

I'm wondering if this could do it. Are these screws supposed to be tight or does that bugger up the headlight aim?

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Re: Odd buzzing sound at 3k rpm. Any thoughts?
« Reply #21 on: June 14, 2021, 09:23:25 AM »
I just noticed something. if you are at the front of the bike looking at the headlight, there are 2 screws. One on the left side and one on the bottom.  Looking at the gap in the headlight, these screws go into some type of spring.

The bottom screw is very tight.  The screw on the left has play. Enough that I can get my fingernail under there and move it in and out maybe 1/2mm or less.

I'm wondering if this could do it. Are these screws supposed to be tight or does that bugger up the headlight aim?
Take the headlight out and go for a ride..

Offline mr_pacman

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Re: Odd buzzing sound at 3k rpm. Any thoughts?
« Reply #22 on: June 14, 2021, 12:09:42 PM »
Take the headlight out and go for a ride..

We might be onto something here. So the front part of the headlight is held on with only one screw at the bottom of the headlight?  The outer ring on mine is loose, regardless of how tight I make the screw so that's definitely an area that could be vibrating. Also, the left hand side screw (which doesn't secure the lamp and just allows it to move the beam left or right) is definitely a source or vibration.

Took the headlamp off and didn't hear the sound. Just put it back on and also didn't hear the sound but maybe something loose got shifted a bit.

More testing tonight but maybe this is the source. Worst case I'll find a whole new assemble and this one feels pretty cheap. Can't believe the front lens is held on with a only one screw

Offline mr_pacman

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Re: Odd buzzing sound at 3k rpm. Any thoughts?
« Reply #23 on: June 15, 2021, 12:02:27 AM »
I taped up the headlight housing and adjusted the screw on the side so it wasn't able to move around. Went for a long ride tonight and no buzzing/vibrating sounds. I'll give it another shot tomorrow and if it's gone, I'll assume that sorted it out.

Thanks again for all of the help with this.

 

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