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Discussion Starter · #1 ·
I’ve just got my very first BMW, a 2020 1250 RT and it’s driving me nuts. It’s brand new, now with 1,300 miles on the clock and at anything above a steady 3500rpm in 4th 5th or 6th gear it has a “pulsating” buzz which comes through the seat and you can also hear the hum hum hum (hard to explain) The Rev counter is steady, the speed is steady without and engine surging but it’s very obvious and mega annoying.

Has anyone experienced anything similar? Any suggestions as to what if May be? Should I be concerned?

TIA
 

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Sounds like a harmonic vibration. Trying to locate the source will take some doing. First you need to talk to BMW service tech. See if it's a common issue. Then try different speeds, gears with similar speed.
 

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Discussion Starter · #5 ·
Sounds like a harmonic vibration. Trying to locate the source will take some doing. First you need to talk to BMW service tech. See if it's a common issue. Then try different speeds, gears with similar speed.
“Harmonic vibration” is a good description. Sounds like I’m going to have to contact BMW.
 

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“Harmonic vibration” is a good description. Sounds like I’m going to have to contact BMW.
Found this to be interesting. It talks about the BMW boxer engine as well.
Good heads up information. Still need to take it to your BMW service tech. They may know exactly what it might be.

 

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I think it would be a good plan to pull the wheels and check the balance. You can buy a reasonable balance machine on Amazon for 55$. Front wheel needs to be with in 5 grams, rear wheel 45 but I always balance them to 5 grams also.
 

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Did you break the motor in using the recommended BMW guide lines or did you ride it like you stole it? I have always had issues with bikes using the recommendation.
 

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Discussion Starter · #9 ·
Did you break the motor in using the recommended BMW guide lines or did you ride it like you stole it? I have always had issues with bikes using the recommendation.
It’s been ridden like it was my wife, lovingly.
 

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Discussion Starter · #10 ·
Found this to be interesting. It talks about the BMW boxer engine as well.
Good heads up information. Still need to take it to your BMW service tech. They may know exactly what it might be.

Brilliant article, thank you !
 

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Discussion Starter · #12 ·
Spoken at length to the dealer who are saying it could be the aftermarket Screen OR Fender Extender OR Crash Bars OR Hugger OR anything else which has been fitted. All of which are ;(

looks like I’ve got a lot of experimenting to do, however the driveshaft does sound very plausible.
 

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Spoken at length to the dealer who are saying it could be the aftermarket Screen OR Fender Extender OR Crash Bars OR Hugger OR anything else which has been fitted. All of which are ;(

looks like I’ve got a lot of experimenting to do, however the driveshaft does sound very plausible.
None of the above, including the drive shaft sounds like the issue to me! My bet is on wheel balancing, which will rear it's head in harmonics. That's what dynamic balancing is all about, even if it's not usually done with motorcycle tires.
 

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Discussion Starter · #14 ·
It’s hard to describe, but the humming / light vibration pulsates too slow for it to be a wheel balancing issue, also it’s not particularly speed related, it’s more related to RPM.

Over the next week or so I’ll remove specific parts and see if that makes any difference. However, I’m not convinced it’s the aftermarket parts (as advised by the dealer) because others would suffer the same issue.
 

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I had a bike years ago that had a harmonic hum or vibration. It drove me nuts. I never did solve the issue and ended up living with it and then eventually selling the bike. Good luck! Those things can literally be unsolvable.
 

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Since it is RPM related look at checking intake balance or vacuum leak. Pulling the plugs is an easy check too.
 

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Discussion Starter · #18 ·
It’s only got just over 1,300 miles and 11 months old so I would be disappointed if it was any of those. However, they’re are on my “to consider” list

cheers
 

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Spoken at length to the dealer who are saying it could be the aftermarket Screen OR Fender Extender OR Crash Bars OR Hugger OR anything else which has been fitted. All of which are ;(

looks like I’ve got a lot of experimenting to do, however the driveshaft does sound very plausible.
Driveshaft would be roadspeed related not gear or motor related, these are very mechanically noisy bikes. My 2018 has vibration at 4,000 and over felt the most in 6th. I thought the 1200 with a timing chain would be noisier than the 1250 with the metal belt but the guys at my dealer think the 1250 is noisier than the 1200.
What kind of bikes are you used to driving?
 

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Discussion Starter · #20 ·
Very good question and I know what I’m about to receive ….. an FJR. But trust me, this pulsating isn’t normal on any bike.
 
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