Front end shimmy.

The old Sportster used to do this all the time. First time I've had the FJ-09 do it. Maybe time to check my steering head bearings I think.

1st check the tire pressure.

Steering head bearings, wheel bearings, tire pressure, tire wear are all possibilities, I would address that sooner rather than later since it could get really scary if it becomes worse.

I'd try air pressure first, then balancing beads in the wheels. After that comes wheel bearings then steering head bearings. Don't forget sometimes rear alignment can be an issue.

Tire pressure was set that morning. The front tire is starting to get a slightly scalloped wear pattern going on. I'm thinking that has a lot to do with it. Also I was leaned way back on the bike because I was trying to get my pocket zipper closed so my phone wouldn't escape. It doesn't do it with my weight forward. It only does it at around 45 mph, above that it's fine and below that it's fine. Not that I'm in the habit of riding no handed but occasionally I'll forget to close a zipper. All I did to stabilize it was just lightly touch my palm to it and it instantly stopped.

The only thing sucky about setting the steering head bearing is it requires a special tool. I hate buying a special tools  but I need to do it anyway. Still need to sync the throttle bodies too, maybe I'll just do a big maintenance weekend some time this summer.

If the tires cupping try 3-5 more psi and see if the shake doesn't disappear completely.  If you don't have tapered bearing in the stem add'em when you can there not a lot of dollars but boy do they help.

Not sure what you're built like.

I'm 6' tall and 260lbs. I run the 2-up tire pressures in all my bikes and they handle way better than at the "Italian teenager" setting.

That being said, weight further back will usually make the situation worse. Loaded touring bikes will get more wobble than unloaded.

I noticed a weave (not a shake like that) on my old Ducati and backing the steering damper off got rid of it.

That's all I got.

If you have cupping, what condition are your front springs, seals and when did you last change the fluid? Is the spring rate set up for your weight?

What markwemple said...

That said, some front ends are notorious for scalloping front tires even if they're in perfect working order (BMW Telelevers like to do that). With normal forks I'd look into the condition of the fork also.

Unfortunately if the tyre is already scalloped, you either may have to live with it or change it out.

the FJ-09 has only been out for 2 or 3 years, unless he is really putting miles on it, I doubt it has bad head bearings or worn out suspension so soon. 

in the video, it looks like he is riding hands free, I have had lots of bikes do that. Shake a little bit with no hands on the bars, but not enough that you feel it when holding on. Cheapest fix is don't let go of the bars.   

In reply to Trans_Maro :

It calls for the same tire pressures fully loaded vs. one up. 36 front and 42 rear. 

Nick Comstock said:

 Also I was leaned way back on the bike because I was trying to get my pocket zipper closed so my phone wouldn't escape. It doesn't do it with my weight forward.

This is a possibility. I took the fairing off of my GL1100 today and found a 3lb weight bolted to the fork tubes. My understanding is they would develop a wobble without it. Also, I read something a while back about the ST1100 (or was it 1300?) police bikes developing a wobble at speed. It was found to be caused by the weight distribution being too far back with all of the extra goodies they attach to police bikes.

FWIW, when I put my LeMans back together, the steering damper was totally shot.

MG used the Tonti frame for all their bikes from the hotrod LeMans to the touring California.

After much research on the forums, the only guys running into a steering shake on a Tonti-framed bike were the guys running a loaded touring model. The consensus seemed to be if you don't have the weight way back on the bike, you don't need a damper on a Tonti-framed Guzzi.

I haven't run a damper for two years, I beat that motorcycle like a wayward red-headed stepchild and I've never had the slightest shimmy, even at ludicrous speed.

In reply to Trans_Maro :

I also believe that was why the Sportster was so prone to it. I was basically sitting on the rear tire with that thing but the steering angle was longer to kinda balance that out I think. 

Other factors for the FJ are I have some weight in the cases. I have my summer bikini screen on and have my handguards removed and replaced with much lighter bar end weights. But I feel the biggest contributor to what happened in the video was my body position coupled with a front tire that's getting worn.