3k-4k rpm buzzing sound

So, I recently obtained a 91 VFR 750 and so far the problems have been very small and have only cost me about 15 dollars to fix.

Now I've noticed that no matter the gear I'm in from 3000-4000 RPM there's a loud buzzing noise. Like a loud bee.

Any clue what could cause this?

Someone on another forum thought maybe something was rubbing, but nothing seems to be loose, and I don't see any rub marks anywhere... And as soon as I get passed 4k RPM's and below 3k the buzzing stops..

It sounds like a giant group of angry bee's..

 

You gotta take those baseball cards out of your tire spokes. LOL.

Sorry I have no idea what your problem might be, it just reminds me of running no name player baseball cards in the spokes of my bike when I was a kid.

 

lol, thanks.

 

coud be a resonance somewhere from plastic fairings or maybe an exhaust baffle.

look for missing fasteners.....

 

Yep for some reason, yea I know you want to know what the reason is, But there's a certain frequency going on that makes a buzz, could be like mentioned a lose faring tab, an engine mount being a tight, wind screen screws are lose, even tire pressure will produce a different vibe. aw Hell just add some slick 50 LOL, There's going to be a number of little this and that's, unfortunately with out experiencing this first hand be hard to tell whats what though, Ho ho ho

 

Yah, I think that's what it is. I can't see anywhere the tires would rub, and I don't see any signs of rubbing... and the fairings have a couple bolts missing, and aren't as sturdy as they could be, so I'm guessing that's probably it. I just don't want it to be something really serious.. but the only thing that makes sense to me is either the fairings or the tires rubbing. I checked the radiator to see if it was a little loose and its not budging.. so..

maybe someday when I get all the stuff the bike needs it'll stop..

 

My 95 acts like a Harley around 4000 rpm. It just starts shaking parts off. I've learned to look for loose hardware whenever the buzzing starts, because I've also learned that stealers want too much money to replace them.
The longer you go with missing hardware for the plastic, the greater the chance of stress cracks forming.

 

it's more than likely the tank buzzing against the frame. I recently repainted my tank and there is a rubber "gasket" of sorts that goes around the front about 3/4 of the way around the tank (basically from where the seat mounts, around the front, to where the seat mounts on the other side). at 3-4K I hit a harmonic and the tank vibrates as you mention. I havent gotten around to replacing the part, but have replaced the rubber separators and washers on the front.

my original part was falling off due to age, and I thought this was cosmetic, been buzzing ever since.

Part 19


$7.69 from ron ayers
http://www.ronayers.com/browseparts.cfm?SearchString=17519-MT4-300&adv=5&kw=fiche.ronayers.com

 

so true:
those "tank buffers" will certainly cause noise if they're missing..
good call, BR

 

I'll check that out and see if that's it. Thanks!

 

Okay, I checked it out. All I have are a few rubber snaps that the tank clips onto. I don't have that long rubber piece on the front of the tank. I pushed on the tank a little and did notice a tiny bit of give, and don't doubt that it could be vibrating. Do I have to take the tank off to insert this rubber strip?

 

yes, you have to take the tank off, but it's really easy. Take of the seat, and it's one bolt underneath your family jewels. Lift the tank about 2" and turn off the petcock and unclip the fuel line and level sensor and the tank is off.

just to check, if the tank doesnt buzz when full, and buzzes when empty, would bet on that rubber gasket.

 

Well, the tank is about 3/4 full and it's doing that buzzing sound. So I guess we'll see. I'll order the rubber gasket on the 1st when I get paid. I have to order a couple bolts and such for the fairings anyway.

One other question: one of the screws in the left side mirror wont screw in. I tried switching screws to see if it would work, but it still didn't. So, that leaves the only option that the threads inside are stripped. Is there anyway to switch that out, or do I have to buy an entire front fairing? The mirror isn't really loose, but it's not as tight as it should be either.

 

you could re-thread with a tap or put whatever thickness of washers needed between screw and mirror to give u a tight fit or drill it out and use bolt and nut.....

 

I'll take the bolt into Ace and see if they have a tap for it. Thanks man

 

Anyway, update:

I took the bike out for a small ride around post today. (being cautious of my speed cause my speedo wont work until I get the part in on Wednesday )

Correction on the RPM speed. It's actually between 4 and 5k... not 3-4. But onto the main point. While I was between 4 and 5k rpm I would hear the buzzing and I pushed down on the front piece of the gas tank and the buzzing got significantly quieter. If I applied more pressure, the buzzing would subside even more. So I think that's it! I'll order that rubber gasket on the 1st and hopefully that problem will be solved.

 

glad you found it... they also buzz at multiples of the 4-5K --- 10K in particular...