BMW K bikes (Bricks)

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1Back to top Go down    vibration on Mon Aug 13, 2018 10:25 am

nobbylon

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I took my RS on a 1000km round trip over rhe weekend to the Ardenne. My friend Martin joined on my other standard K. Both bikes ran beautifully with no problems or oil burn however I did notice that between 85 and 100 mph there is vibration or a heavier buzz to the whole bike. Is this normal on the 8v. The front fork seems to also start a bit of a chatter at same speeds. Maybe the forks need new bushes. I have 10w in at the moment but maybe could do with 5 instead. 
I have to admit that the RS fairing is a nice place to be behind on the motorways. Averaged appox’ 50 mpg on both bikes.
Weather was dry and 20-28 deg C and the Pirelli sport demons I put on are superb. Absolutely sure and very confidence inspiring tyres. Ran with 38F and 42R.


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K100RS July 1989
K100 Dec 1983 
R90s June 1975
R75/6 Feb 1976
F650GD May 2001
    

2Back to top Go down    Re: vibration on Mon Aug 13, 2018 5:34 pm

Dai

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The buzz is normal. Around 60mph you get the first bit of vibration, then another lot at about 85 mph. The problem is, once you hit 85mph the buzz doesn't get any worse. There's been a few times that I've been grateful for blind Guards on the run to/from Dublin.

Just FYI: I run 38/40psi in the tyres. I've found the K surprisingly sensitive to tyre pressures; once it drops back from 40psi to about 35-36psi, it really tells me about it. Due to the old 'leaky rim' problem I need to check tyre pressures once a week.


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'83 K100 upgraded to K100RS spec
Others...
'78 Moto Guzzi 850-T3, '79 Moto Guzzi 850-T3 California,'93 Moto Guzzi 1100ie California,
'03 Suzuki Blandit GSF600SK3 (NFS any more because wifey has claimed it)
    

3Back to top Go down    Re: vibration on Mon Aug 13, 2018 8:06 pm

Point-Seven-five

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@Dai wrote:Just FYI: I run 38/40psi in the tyres. I've found the K surprisingly sensitive to tyre pressures; once it drops back from 40psi to about 35-36psi, it really tells me about it. Due to the old 'leaky rim' problem I need to check tyre pressures once a week.
My bikes let me know the tires need air by being very reluctant to being pushed around the garage.  At about 35psi front and 36 rear, they begin to feel about twice as heavy.


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Present:
1994 K75RT
1994 K75S
1992 K100RS

Past:
1982 Honda FT500
1979 Honda XR185
1977 Honda XL125
1974 Honda XL125
1972 OSSA Pioneer 250
1968 Kawasaki 175
    

4Back to top Go down    vibration on Tue Aug 14, 2018 5:14 am

audibob

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My k used to buzz a lot at between  3200 and 3800 revs, but was reasonably smooth on the bars from then on.

Someone on the forum suggested using rubber washers to help isolate the handlebar clamps from the fork trees 

which helped a lot.

I have had my injectors refurbished, new FPR, and balanced my throttle bodies at 5k revs.

New front wheel bearings too.

I did set my timing to max advance as per Rick g , but it now sits midway between the factory setting  and full 

advance.

My bike is now extremely smooth, even when I use a strong grip on the bars, I feel nothing at 5k and 

beyond.

This is great, but I have to watch the speedo more now..... Twisted Evil

This is my second K bike, and as with my first,  if I do feel a buzz through the bars, I close the throttle 

VERY SLIGHTLY without dropping road speed, and the buzz disappears.

I find the K bike  perfect for long distance riding.

I hope you cure  your vibrations / buzzes, there is nothing worse whilst riding .

Bob


__________________________________________________
Yamaha 90
Honda CD 175
Honda CB 360 
Triumph T 140V Bonneville
Triumph T150 Trident
Honda CB750 F1
Cz 175
Yamaha XS 750
R 100/7
R 80
K100 LT
K100 LT current bike
    

5Back to top Go down    Re: vibration on Fri Aug 17, 2018 11:24 am

nobbylon

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I did the +4 degree advance today by scribing a line on the plate and turning the width of my 2.5mm screwdriver. 98 fuel in and it does seem more throttle responsive and has a less buzzy feeling to it. I need to find a quiet road to explore the 85mph plus range. Thanks for all the suggestions.


__________________________________________________
K100RS July 1989
K100 Dec 1983 
R90s June 1975
R75/6 Feb 1976
F650GD May 2001
    

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