Do your bars wobble?

[shinyribs]

I'm not talking about "tank slapper" ( I hate that term), but I noticed recently that if I take both hands off the bars that they flutter around. Not a lot, but noticeable. I never feel anything under normal circumstances ( hands on the bars) or at any speeds. These bikes do seem prone to shake their head when you land a wheelie too hard, but I chalk that up to not having a lot of trail. 

 

I just happened to be coasting down a hill towards a stop sign and took my both hands off the bars for a second to tighten up a glove strap. Was kinda surprised to see the bars slightly fluttering and am just curious if anyone else has noticed this. 

[CarGuy7a]

I've not noticed this on mine but then again I haven't taken my hands off the bars too many times. The times I have though the bars stayed perfectly solid no fluctuation. Could have been slightly uneven pavement and the list goes on of what could make the bars do that. Just to be certain I would check and make sure your forks are even in the top triple clamp and the wheel is lined up. Loosen the axle nut where it's still good and snug but not sloppy loose, sit on the bike and while keeping the front wheel straight hold the front brakes and bounce the front suspension up and down. Then re torque the axle nut. Take a ride and see if it still does it. If your front end has not been taken apart since the dealer put it together, sometimes things can be slightly misaligned and give those slight issues.

[i28]

^what he said. I'd check if the forks are misaligned. You can even look to see if the front wheel is aimed straight (or if it's slightly off) when your handlebars are completely straight.

Is the tire balanced? possibly misaligned?

[YZEtc]

Haven't noticed this on my FZ-07, though I have on other bikes I've owned.

[faffi]

Not in the slightest, but sometimes it doesn't take much to set this off if a bike is on the edge. A bit too much rear preload or a sagging fork or a tyre just out of round and/or balance can be enough. My Honda CB1100F (1983) would shake itself to a crash if allowed around 60 kph, and was pretty wild between 30 and 90 kph. But with both hands on the bars, it was dead stable, even scraping pegs and stands around 125 mph bumpy sweepers. 

[stickshift]

4 hours ago, shinyribs said:

I just happened to be coasting down a hill towards a stop sign and took my both hands off the bars for a second to tighten up a glove strap. Was kinda surprised to see the bars slightly fluttering and am just curious if anyone else has noticed this. 

Rake is pretty steep on these bikes at 24.5 degrees, it helps with manoeuvrability and 'light' handling among other things. Longer shocks/raised rear will increase rake again.

 

When you let off the throttle it compresses the fork and increases rake angle, going downhill will increase the weight on the front tyre.

 

The bar waggling that you experienced is not really that surprising since in your situation the geometry is tending towards instability. We reap the benefits of this at amost other times so it's a good thing generally!

[Beemer]

I noticed it awhile back and pointed it out to DewMan on a ride and his were the same way. They just tend to flex a little but they are secure, not to worry.

[shinyribs]

Thanks for chiming in guys. I didn't figure it was just the nature of the bike. I never noticed it in the first 5k miles, so I'm curious now if my new tires are to blame. They have about 1500 miles on them, but I haven't thought to check for this. I'll give the bike a good once over and see what comes up. 

 

Thanks for the tips on the forks. I'm very particular about the mechanics on the my bikes, especially the dirt bikes that require a lot of fork maintenance. I may have overlooked something. Can't imagine a tire is out of balance, but it'll only take a minute to double check. 

 

Thanks guys. 

[r1limited]

Never experianced this, even when standing on the seat and doing the hokie pokie

 

Seriously, no I have not.  I suggest to make sure or at min check all torque on tripples including the stem.  As well as alignment of forks,

[rick]

1st thought that came to mind for me was tire wear. But 1500 miles, not enough. 

 

2nd thought - your mentioning landing wheelies. You might want to lift the front off the ground and turn the bars side to side to feel for any brinelling - as in dings in the stem bearing races. 

 

While it's up, check for play. Worn/ loose stem bearings can also cause this. 

 

If the forks are tweaked, you'll see it in the bars as they won't point straight when yer going down the road.

 

Back in the old days of 3.25" x 19" tires, hands-free wobbles at 40 mph were a big problem. With a modern 120 x17, not so much.

[DewMan]

13 hours ago, Beemer said:

I noticed it awhile back and pointed it out to DewMan on a ride and his were the same way. They just tend to flex a little but they are secure, not to worry.

I think you're talking about something different that what is happening here... You're talking about the rubber bushings for the handlebars. They're talking about a shimmy in the front end when he lets go of the bars if I understand it correctly.

[rick]

Hmm, are we talking back and forth together or oscillating left to right? 

 

The bars do move on their flubber mounts a bit when you tug on them (not while riding) 

 

Soo, good point, just the bars or the whole front end - wheel and all? i was thinking latter. 

[shinyribs]

Oscillation, yes. Not the rubber bar isolators which grossed me out immediately. I complained about those before I even took a test ride lol

[derekfz]

I changed my tires away from the stock bt023 tires and my bike is WAY more stable. I can switch lanes over uneven surfaces and my bike just tracks straight now like it should. I didn't realize they where so bad til I got a better tire.

[Beemer]

Was the road smooth, have a few small bumps or imperfections in it to cause a commotion? I'm going to ride mine today and video the bars (hands off) to see if I can capture what you're talking about.

[stickshift]

15 minutes ago, Beemer said:

Was the road smooth, have a few small bumps or imperfections in it to cause a commotion? I'm going to ride mine today and video the bars (hands off) to see if I can capture what you're talking about.

What angle decline & what is OP's shock length...? 

 

Doubtful that you can replicate the conditions unless you know at least these basics.

[rick]

9 hours ago, shinyribs said:

Oscillation, yes. Not the rubber bar isolators which grossed me out immediately. I complained about those before I even took a test ride lol

One more thing to check if you can lift the front - feel for any roughness/noise or play in the wheel bearings. You might have to pop off the calipers to eliminate their drag.

 

Also have a close look/feel to the sidewall of the front tire. Any dips or bumps could indicate a wonky belt. Kinda rare, but hitting a sharp pothole can do it. Dunno what your streets look like, but with a winter that just won't quit, the roads here in the rust belt look bombed and strafed.

 

Maybe better than any motorcycle I've ever owned, this FZ goes straight w/o hands. Something's not right.  

[Beemer]

55 minutes ago, stickshift said:

What angle decline & what is OP's shock length...? 

 

Doubtful that you can replicate the conditions unless you know at least these basics.

No doubt I can't duplicate the conditions without knowing the exact conditions, I'm not attempting that, I just want to see if my handlebars wobble the same way when I let go of mine, that's all. Whether it wobbles or not proves nothing by comparison.

[r1limited]

@shinyribs I am sure you know how this is done.  One further step is to drop lines (PLumb Line) from the edge of the triples measuring from the tip of the weight to the line on each side.  This measure should be correct both sides if not triples are not alligned...

 

https://www.motorcyclistonline.com/how-to/how-to-check-front-and-rear-motorcycle-wheel-alignment-mc-garage-tech-tips#page-7

[shinyribs]

1 hour ago, Beemer said:

Was the road smooth, have a few small bumps or imperfections in it to cause a commotion? I'm going to ride mine today and video the bars (hands off) to see if I can capture what you're talking about.

The road was smooth. I'm positive whatever is causing is on the bike, not the road. It's a very slight flutter. The tips of the bar are probably moving 1/16" or maybe 1/8" at most. 

[shinyribs]

5 hours ago, derekfz said:

I changed my tires away from the stock bt023 tires and my bike is WAY more stable. I can switch lanes over uneven surfaces and my bike just tracks straight now like it should. I didn't realize they where so bad til I got a better tire.

I can understand that. I didn't really have any complaints about my BT023's at first, but they did get pretty slippery towards the end of their life. Then I put on a pair of Conti Motions and was amazed how much better everything was. Traction, feel, small bump compliance....just a better tire all around. That's one reasonI hope it's not tire related, but we'll see. 

 

 

Weather knocked me out of working today, so I'll try to pop the FZ up on the lift and see what I can find. Thanks again for the the information and ideas. 

[rick]

Back in the days of my old R bikes - my 76, R90/6 in my avatar - aka "the brown stain" included, tension the stem bearings played a huge role in how stable the front was. Adjusting the stem bearings was by feel. Thankfully, with the way new stem systems are designed, it's not done that way anymore.

 

But the test for a proper adjustment was to go find a place to coast downhill a wee bit at 40 mph, loosen yer grip on the bar with one hand and give the bar a bump with the other. If the bearings were too loose (no play, but not enough drag), this would invoke a nasty wobble, that needed to be stopped - as in now. If the adjustment was right, the bar would wag a couple times and then go straight again.

 

The good ol days weren't always all that good, lol.

 

[shinyribs]

lol I hear ya. Sounds about like my old SOHC CB750's. Great bikes, but definitely a different animal compared to anything modern. 

 

Haven't had time to look at the bike, but I had to run out for a couple errands. The wobble is sorta random. I was checking for the wobble at different speeds and inclines. Above 50 mph the wobble is very consistent, but it won't wobble if going up a noticeable grade. Going downhill makes it more consistent to wobble, but doesn't increase the severity of the wobble. Anything below 20-30 mph is rock solid, even if I try to lean forward/backward, sit forward/backward, etc.

 

So it seems speed and a downhill slope definitely make it more prone to wobble. I'll check all the things you guys suggested first. If  don't find anything wrong there I may play with raising my front sag some. I'm not using all of my available travel in the fork ( been monitoring a zip tie on the stanchion), so I think I may be giving up a little comfort there. I think I might raise the front sag number a bit ( preload spacer) and then reduce the air gap to allow for a little softer damping. That should bring the nose of the bike up some while allowing me to use a touch more wheel travel. Sound right to you guys?

[shinyribs]

Fixed! I got the bike up on the lift and decided it'd be best to verify wheel alignment before anything else. Pretty much did it exactly like what is spelled out in r1limited's link. 

 

Before I even pulled strings I knew the rear wheel was off when I looked at the chain sitting off-center on the sprocket. 

 

The wheel alignment was off. There was nearly an 1/8" difference in string gaps at the front tire! I straightened that out and went for a test ride. I was tempted to double check the forks while the bike was up, but I wanted to only change one thing at a time so I could verify the culprit. Here's how inaccurate the swingarm marks are. 

 

Clutch side.

Throttle side.

 

Chain run after aligning the wheels. Hmm...still not 100% centered, but very close.

 

 

Test ride was a success. Zero bar flutter at any speed now, uphill or down. That's what you get for trusting swingarm marks because " it's a modern bike, the marks are probably alright....".

 

 

 

 

[shinyribs]

Measured my ziptie while the bike was up and saw that I'm only using 4.2" of the available 5.1" of wheel travel. I'm happy with the handling and my current sag numbers, but the fork are just a teeny bit harsh. Not sure if I want to reduce air gap or try thinner fork oil.