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TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: shoebox1.1 on August 06, 2015, 12:16:54 PM

Title: 5000 RPM HIGHWAY BUZZ IN HANDLEBARS
Post by: shoebox1.1 on August 06, 2015, 12:16:54 PM

4000 RPM AT 60MPH is glass smooth.. kick it up to 5k plus on my 87 k75s and the bars get quite buzzy.. having to shake rhe hands quite a bit,  can i fill the bars with shot or silicone etc?

Title: Re: 5000 RPM HIGHWAY BUZZ IN HANDLEBARS
Post by: rbm on August 06, 2015, 07:25:24 PM

K75s should be smooth throughout their power range.  If it's buzzing, check TB sync or look for air leaks in the intake system.  Filling the bars with shot is a band-aid that masks the symptoms without solving the root cause.

Title: Re: 5000 RPM HIGHWAY BUZZ IN HANDLEBARS
Post by: TX brick on August 06, 2015, 10:30:56 PM

Check the two bolts that hold the muffler at the rear. Mine were loose when I bought the bike and it would put my hands to sleep until I tightened them.

Title: Re: 5000 RPM HIGHWAY BUZZ IN HANDLEBARS
Post by: shoebox1.1 on August 07, 2015, 08:16:27 AM

Ok great! I'll check those bolts.  Thanks

Title: Re: 5000 RPM HIGHWAY BUZZ IN HANDLEBARS
Post by: K75RT Keith on August 07, 2015, 10:22:47 AM

An exhaust leak at the connection between the collector and muffler can also cause your problem. 

Check for the isolation pad between the muffler mount and frame that small piece of rubbery material makes a big difference.

Title: Re: 5000 RPM HIGHWAY BUZZ IN HANDLEBARS
Post by: shoebox1.1 on August 07, 2015, 11:27:58 AM

Great! I can't wait to get home and check it

Title: Re: 5000 RPM HIGHWAY BUZZ IN HANDLEBARS
Post by: K75RT Keith on August 09, 2015, 10:29:36 AM

Had a talk with a older BMW master technician who knows K bikes. He said you're going to get some buzz somewhere in the power band even in the 3 cylinder K75. It is the nature of a piston powered internal combustion engine. Anything that is loose, air leaks, out of balance throttle bodies, etc. will exacerbate the buzz.

Title: Re: 5000 RPM HIGHWAY BUZZ IN HANDLEBARS
Post by: johnny on August 09, 2015, 11:21:10 AM

bmw master technician... ha ha ha... now thats funny...

exacerbate the buzz... mine mine mine... all mine...

j o

Title: Re: 5000 RPM HIGHWAY BUZZ IN HANDLEBARS
Post by: shoebox1.1 on August 09, 2015, 11:26:33 AM

I checked the muffler mount was ok just gave the bike a once over and am not seeing anything loose
Let me say this.. I work on cars for a living for 23 yrs my hands might be more tingle prone due to carpel tunnel. My gel gloves might not be good enough.  I think what I'm felling in the bars might be normal. I need to have my dad ride the bike and compare it to the 15 k bikes he's owned.   Thanks so much!

Title: Re: 5000 RPM HIGHWAY BUZZ IN HANDLEBARS
Post by: bizzaro on August 09, 2015, 11:45:26 AM

Hey, could be worse.  Mine starts to vibrate at 3.8 to  4k+. That sux cause if I ever want to drive 50 to 60, police won't bother you much there, but all the vibs come in about then. Also at 4k I get this annoying buzzing sound in all gears. Reminds me of a remote  controll airplane or truck tires on the pavement?? BBBBUUUZZZZZZZZZZZZZZ! Shoot up to 4.5 or so and it is gone. seems to be a bit louder on deceleration.  ( I am worried it is the splines?) So It is either granny speed or demon speed for me!