Hi All,
Has anyone has a problems with a slight vibration, I think rpm related ?

My '07 Roadie only has about 375 miles but is developing a slightly uncomfortable vibration at 68 mph in 5th that can be reporduced at 28 mph in 2nd. It is not something that will put you in a permanent state of numbness, but your feet feel like the are small marbles under them on the boards. Above or below the mentioned speeds, it is not there.

Not too worried right now, unless it gets worse, but would like to find it and remedy if possible.

Any hints would be appreciated.

Thanks,
John

Hi John,

Based on the symptoms you reported, it sounds like what you are experiencing is normal. Every mechanical system has a property called "resonant frequency", or a frequency at which the object vibrates naturally. (acoustic musical instruments rely on this property to make sound) For internal combustion engines, that resonance is RPM related, because when the crankshaft and pistons are moving, they behave like a reciprocating mass not unlike a guitar string. At a certain RPM, they reach their resonant frequency and as a result, the entire engine start shaking. (How much they shake is determined by how balanced the crankshaft is, which is why motorcycles with counterbalancers shake less than a Roadie, but even they shake a little bit at their resonant frequency.)

My '04 Roadstar starts shaking rather seriously at about the same RPM as yours, which is annoying, but it does warn me when I am going over 65 The outboard motor on my boat does the same thing around 4500 rpm, but 100 rpm above or below, and its smooth.

Bottom line is that its normal, espically for a V-twin.

Hope this helps!
-Akela

Mine doesn't vibrate at all































When it's turned off!!!

Hey John....do you by chance have aftermarket pipes? Well even if you don't, check to make sure your front header nuts for your pipe are both tight....not super tight but snug. I had a problem last summer on my trip, that I kept feeling a wierd vibration on my floorboard at certain rpm's. come to find out my header bolts weren't all that snug. I snugged everything up, and all is good. Try it out. Cant hurt.<br><br>Post edited by: beefcake2play, at: 2007/03/08 17:24

Thanks for the replys,
Akela, this is pretty much what I thought was going on only I was calling it &quot;harmonics&quot; for lack of a better word.

Big Bear, I have exactly the same symptoms myself.

Beefcake2play, I will check when I go to the garage in a bit. I have had the pips off and drilled the mufflers, so...

Thanks for the input all,
John

You own a Honda in the past? Spoils you for SMOOTHE.........

Mine vibrates similarly. I just shift/ride around it. It is much less noticable when I take the Woosie gear off (windshield and lowers) In about another month. Not quite ready yet. When my AM temps hit the 60's, I'll dump 'em.

68 in fifth gear sounds like your lugging it to me. i would vibrate to if i was being lugged i was told not to even think about fifth till you get close to 90.

junglebear11 wrote:
68 in fifth gear sounds like your lugging it to me. i would vibrate to if i was being lugged i was told not to even think about fifth till you get close to 90.

WHAT??!!

Musky wrote:
junglebear11 wrote:
68 in fifth gear sounds like your lugging it to me. i would vibrate to if i was being lugged i was told not to even think about fifth till you get close to 90.

WHAT??!!
DOUBLE WHAT!!!

see this is the problem i bought this bike from a dealer, it was used. i don't know what the guy did to this thing before i got it, but i can be running in fourth at eighty and not even be hitting 2800 rpms. this thing has some tall gearing for shure. my hogs never did that but this shure does.