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Discussion Starter #1
For about a week a was getting a noise that sounded like the fairing vibrating around the headlight every time I had gone above 8,000 rpm. It would get so loud sometimes my mind would make the noise louder than the exhaust. Well, I tightened-loosened-tightened every allen bolt and it still was making the noise. inspected around the radiator area a dozen times and no luck. However, I didn't touch the under cowl because I swear it was coming from the head light area. Yesterday a small leaf was stuck to the underside of the bike and when I pulled it off I saw the under cowl move. When I changed the oil 900 miles ago I must have not tightened the highlighted bolt in the picture because it was 2 complete turns of the wrench loose. Took the bike for a ride and no more noise. I knew there was nothing wrong with the bike the whole time because it wasn't a sound that an engine and transmission makes but it did get kind of frustrating not being able to locate what part of the fairing was loose.
 

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I get it too, haven't been able to identify it. I'll take a look when I get home!

My oil hasn't been changed yet, but perhaps the dealer forgot to tighten it? Weird so many people are getting the same rattle. Wonder if the bolt/hole has some defect...
 

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I wouldn't be surprised if the dealer forgot to tighten it.
Or maybe it came lose over time from vibration.
 

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Discussion Starter #4
I get it too, haven't been able to identify it. I'll take a look when I get home!

My oil hasn't been changed yet, but perhaps the dealer forgot to tighten it? Weird so many people are getting the same rattle. Wonder if the bolt/hole has some defect...
Unfortunately, I did the oil change myself so it would be my fault if anybodies but I found if the holes aren't lined up perfectly when tightening the bolt it binds up and it is easy to mistake that it is tight because it feels snug but then if you shift the undercowl a little with your hand and it lines up the holes and you can tighten the bolt down the rest of the way.
 

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There is a widely reported rattle starting at 5000 rpms on the CBR250r if you read the forums. Not sure your rattle is the same thing though. All I get on my CB300f is a rattle when I let OFF the throttle quickly from higher rpms. Don't think that's the same as your rattle. Far as I know the CBR250r rattle has never been solved. Theories include valve springs, dashboard, too-low octane, some sensor, loose fairings, valves out of adjustment, plus a couple others. In any case the rattle seems to affect 4 different years of the engine and nobody has had an engine blow up. Still, who wants to hear a dang rattle. Yours might be something simple too. I checked over everything on mine. Took off the side fairings, seats, checked all the fasteners. I've tried riding and grabbing different parts of the bike to stabilize it if it is fairing. No help. I think it is coming from the engine though. Only other thing mine might be is a leak in the intake manifold. Mine sounds a little more like when you used to put a card in your bicycle spokes as a kid. Again, we are probably not talking about the same annoying sound though.
 

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Trying to get some info on the "rattle" issue. I LOVE my bike. My only gripe with my new CBR300R is the rattle noise right around 4000 - 5000 RPMs, especially when closing the throttle. My issue sounded like the OP's issue with the noise coming from the headlight area consistently. The difference being it happens at a much lower RPM than OP's.

I wear earplugs, but the rattle is actually louder than the exhaust and wind noise through the earplugs. I have tightened all the fairing bolts. Anyone have any other suggestions on where to look? I wouldn't mind sticking some heat-resistant foam someplace. Just need to know where to start if someone already figured this out. I realize this new motor has a longer stroke increasing vibes, but I really want to solve this issue.
 

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It might be worth it to go over all screws that hold down the faring and seeing what play there may be going on that could be the culprit since as far as i'm making it out to be here, it's to do with the faring and nothing that seems to be from a functioning part of component.
 

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I've just recently noticed a croaky rattle noise seemingly coming from the radiator or frontal area of the bike under the forks, around 4500 rpm I'm getting mine, It is driving me mad not know what it is!

Every bolt is tighten, nothing is loose or stuck in it. I dont know what to do :(
 

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I've just recently noticed a croaky rattle noise seemingly coming from the radiator or frontal area of the bike under the forks, around 4500 rpm I'm getting mine, It is driving me mad not know what it is!

Every bolt is tighten, nothing is loose or stuck in it. I dont know what to do :(
had the same thing, I switch for 95 gasohol and noise disepear

Don't know about you but my cooling fan is on all the time and you?

Why you didn't answer me about those plugs, I sended you msg and bump your thread also ?

thanx
:)
 

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I bought my CBR300R 27 January 2015. Have now travelled 760km. I notice a rattle noise at around 6500rpm especially around the 80km/h. Iv'e still got to take the fairings off to have a look but it will be in for its first service at 1000km so will mention it to the shop at that time. If anybody has had a similar experience different to the loose fairng bolt let me know, that would be great.

Awesome bike though especially on the tight turns :)
 

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I bought my CBR300R 27 January 2015. Have now travelled 760km. I notice a rattle noise at around 6500rpm especially around the 80km/h. Iv'e still got to take the fairings off to have a look but it will be in for its first service at 1000km so will mention it to the shop at that time. If anybody has had a similar experience different to the loose fairng bolt let me know, that would be great.

Awesome bike though especially on the tight turns :)
A few owners inc myself have noted a vibration/resonance that seems to set in above 6000RPM, but I wouldn't call mine a rattle.
I was out for a ride today and I thought maybe it has improved with 4000km showing on the clock, but then maybe I'm just getting used to it.
 

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had the same thing, I switch for 95 gasohol and noise disepear

Don't know about you but my cooling fan is on all the time and you?

Why you didn't answer me about those plugs, I sended you msg and bump your thread also ?

thanx
:)
Ive not been on recently Ill send u a message now
 

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Yesterday a small leaf was stuck to the underside of the bike and when I pulled it off I saw the under cowl move. When I changed the oil 900 miles ago I must have not tightened the highlighted bolt in the picture because it was 2 complete turns of the wrench loose.
Thank you I will check mine now to see if its the same issue, I had my oil changed at 600KM Must have made the same mistake!
 

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This bike does seem to have more than its share of rattles, some maybe left over from the CBR250R. So far the only issue I've had was that flapping noise when I would let off the throttle. Turned out that was because my gas octane was too low...shouldn't have been, but since changing over to premium, the flapping noise has not returned and since it was there all the time before, it's safe to say it was related to octane rating. It does seem weird that mine is the only bike that has been reported with this flapping sound...unless people are using higher octane gas in their bikes.
 

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My noise is at about 5000 rpm when the throttle is held steady,not open and not closed.It too sounds like a card in a bicycle spokes.I was using Gasohol 91,changed to Gasohol 95 and no difference what so ever.If it was detonation it would occur when the engine is under strain with the throttle open.Also the 10% alcohol in the fuel will give a higher RON.
 

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My noise is at about 5000 rpm when the throttle is held steady,not open and not closed.It too sounds like a card in a bicycle spokes.I was using Gasohol 91,changed to Gasohol 95 and no difference what so ever.If it was detonation it would occur when the engine is under strain with the throttle open.Also the 10% alcohol in the fuel will give a higher RON.
You've describe what I have it sounds exactly like this. its a humming flapping sound its pissing me off so much when I ride.
 

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Are you guys with the flapping/humming noises running standard exhaust systems?
I've got no idea what it is, just curious.
I just have a physical vibration, no odd noise with it.
 

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My noise is at about 5000 rpm when the throttle is held steady,not open and not closed.It too sounds like a card in a bicycle spokes.I was using Gasohol 91,changed to Gasohol 95 and no difference what so ever.If it was detonation it would occur when the engine is under strain with the throttle open.Also the 10% alcohol in the fuel will give a higher RON.
You've describe what I have it sounds exactly like this. its a humming flapping sound its pissing me off so much when I ride.
So we all have to same thing:(

And my bike will be going for the second time for leaking oil, first time was from the bottom gasket and this time it's the top one

gasohol91 or 95 is the best for the bike ?
 
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