Front end wobble at highway speeds near large vehicles

[thewrenchbender]

1 hour ago, nhchris said:

The FJR is almost 300 lbs heavier than your 900 GT.  And that fact might be in play.

Downside of a light weight bike is it gets knocked around a lot more than a big touring machine.

I came from an ST 1300 and there was a learning curve with my FJ as I adapted to it.  I don't linger in the turbulent air of other vechs.  Either pass em or back off till it's clean again.  And when passing I expect a bit of tracking drift and jitter so it's not concerning any longer.

I have motopump risers and have to sit straight up to keep my neck “straight” if I want to ride without my right arm alternately going numb/burning neuropathy.

Regardless of other comments, as indicated, if I don’t climb up on the tank, the GT becomes unstable at speed. The at-speed weave is virtually identical to the weave I get when caught in the slipstream behind various tractor-trailers. 

My FJR had a lot “heavier” front end, the GT is much “lighter”, and my weight/sitting upright exaggerates the issue. 

As I’ve indicated, handguard removal and changing windscreens made it a little “better”, but the tendency was still 100% there.

With regard to the “strangling the bars” comments, gripping the tank with my knees/or relaxing that grip, or indeed gripping the bars only hard enuff to keep the throttle pinned makes zero difference.

Shifting my weight drastically forward is the only thing that reduces/stops it.

Shifting forward also reduces the tendency for the weave from a semi.

My FJR was rock-solid at 145+, my GT starts to wander well below the 132 indicated “shut off”.

Also as indicated, am hoping a different front tire may help some also.

Using Dave Moss’s recommended settings, my front/rear treadwear is looking good, have verified the front/rear condition mechanically, and tried both more and less neck bearing pre-load than the “book” with little effect.

I have not tried removing the panniers because the bike is not really useful for me without them.

[betoney]

*In my experience*  I have ridden the stock FJ/FZ and XSR and whether its aerodynamics or suspension, the front end feels light (fluttery) on all of them with the steering geometry as delivered from the factory.  I found that raising the rear (aftermarket shock) and lowering the front slightly, moves the weight bias more toward the front dramatically changing the light front end feeling. 

I ride highways all the time and when encountering big rigs or large SUV's/motorhomes, I get more helmet flutter than any bike shaking/wobbling.  I don't use the factory handguards or own a large windscreen either, so my experience might be different than others.

[PhotoAl]

Rode 500 miles yesterday lots of miles across Kansas in stiff winds that varied from headwinds to  side winds.  Had to pay attention but I never felt the bike wobble or weave, I did get blown around a bit.  In crosswinds I’ve always had to be quick countersteering to keep from getting blown around.  Someone mentioned the buffeting of the shoulders, yes I noticed that but it did not weave.  Have lots of miles on my previous bike and mentally was comparing how the Tracer was compared the the BMW F800GT.  The difference IMO is only that the FGT had a MadStad and the Tracer the stock windscreen.  I feel the wind more but don’t move more.  Have not had any trouble getting by trucks wether fast or slow.  I’m aware of comments about weaving and am watching for it but haven’t seen any hint of it.  Bike is fully loaded, I’m 5’10” 175 wo gear, sidecases full, large duffle on the rear seat plus small bag on top of that.  Rear preload set to 20 clicks, this morning checked tire pressures and found them to be at correct “low” pressures, set to 36f 42r.  Better windscreen is high on my list of mods when I get home.  Bike has really impressed me with its stability.  Previous bikes have been 2004 FZ6, 2012 CBR600RR, 2014 Kawasaki ZX6R 636 ABS, 2016 BMW F800GT.

[Buggy Nate]

Yeah I’ve had this a fair bit being stuck behind trucks on the freeway. A few things helped as in a better rear shock, with adjustment for more length. Fork upgrade, but the main thing that resolved it was pissing off the stock screen for a shorty. I’ve run this screen with both stock and aftermarket hand guards with no issue. But the bigger screens are nicer in the cold. So use a bit of throttle to get out of there!

[Gamarth]

Had a chance to remove the hand guards and take it for a quick spin before some storms came in. Without the hand guards installed I experienced little to no wobble while passing cars at highway speeds.

Thanks for the suggestion!

[TheBigG]

7 hours ago, nhchris said:

The FJR is almost 300 lbs heavier than your 900 GT.  

Off topic but the difference is "only" 80kg (170lbs)

[Coop]

On 9/8/2020 at 4:45 PM, nhchris said:

The FJR is almost 300 lbs heavier than your 900 GT.  And that fact might be in play.

Downside of a light weight bike is it gets knocked around a lot more than a big touring machine.

I came from an ST 1300 and there was a learning curve with my FJ as I adapted to it.  I don't linger in the turbulent air of other vechs.  Either pass em or back off till it's clean again.  And when passing I expect a bit of tracking drift and jitter so it's not concerning any longer.

I came from an ST1300 as well and it had a little flutter behind trucks.  Compared to it the Tracer is a statue.  I've had no problems with either the stock shield or my MadStad.  Another thought about trucks, if one of those tires shuck their tread in front of you have fun.

[Ddog gt]

When I first got this bike it felt very light in the front and found it did move around a bit at speed. I have raised the forks 8 mm above the triple tree to put more weight on the front. This also helps with turn in. Bike feels rock solid now at any speed. 

Edited September 9, 2020 by Ddog gt

[tktplz]

On 9/8/2020 at 10:31 AM, Gamarth said:

I don't recall having this issue on my previous bike (07' Suzuki Bandit 1250)

And your Zuke 1250 is at least 100 lbs heaver. I noticed it when I switched from my 2000 ZRX1100 which weighed in at about 550 to 565 lbs. I have taken off my hand guards too. I have nice Rev Tech H2O  gloves and heated grips. I never have been a fan of the look but I heard they could cause the high speed wobble. Thanks but no thanks.....I love my high speed sweepers. Now I didn't want to ride my ZX11 Ninja on windy days. It had a habit of getting blown around. And of course check the tightness or lack there of on your triple tree neck bearings. SKIP where are you with values, torque, etc?????

[thewrenchbender]

1 hour ago, Ddog gt said:

When I first got this bike it felt very light in the front and found it did move around a bit at speed. I have raised the forks 8 mm above the triple tree to put more weight on the front. This also helps with turn in. Bike feels rock solid now at any speed. 

Thanks. Raising the forks 10mm and dropping 2-3 lbs out of the front tire was really the only thing that made any difference. But it sure ain’t “solid” now...

[Ddog gt]

Forgot to mention I also changed the fork oil to 10 weight. And raised the oil level to150 mm from the 175 mm recommend in the manual. This is the cheapest way to go instead of a revalue. (200 lbs. ready to ride).

[nhchris]

14 hours ago, Ddog gt said:

...  I have raised the forks 8 mm above the triple tree to put more weight on the front. This also helps with turn in. Bike feels rock solid now at any speed. 

Raising the forks reduces the already short  front suspension Trail spec of the Tracer.  Less Trail makes the bike less stable at speed, not more.

Since the Tracer/FJ is quick to turn in in stock form, I am not sure there is any reason for this procedure, especially on a street bike with an already twitchy front suspension.

And, I'd be very curious to know exactly how much weigh gain occurs after an 8mm fork raise. Has anyone every measured the increase in front wheel load after raising the forks?  

Edited September 10, 2020 by nhchris

[roadrash83]

I installed the Givi hand guard extenders on my GT and  to my surprise they really  helped with the turbulence wobble.

[thewrenchbender]

23 minutes ago, nhchris said:

Raising the forks reduces the already short  front suspension Trail spec of the Tracer.  Less Trail makes the bike less stable at speed, not more.

Since the Tracer/FJ is quick to turn in in stock form, I am not sure there is any reason for this procedure, especially on a street bike with an already twitchy front suspension.

And, I'd be very curious to know exactly how much weigh gain occurs after an 8mm fork raise. Has anyone every measured the increase in front wheel load after raising the forks?  

Did it in desperation, didn’t expect it to make a difference-but it did. 

I’m not slamming people whose GTs don’t weave (and it’s def more of a weave than a full-on head shake). Not saying that people that removed the handguards/went back to a stock windscreen didn’t see a change, just know on my bike it made no difference.

Spent several days/300ish miles confirming that it just plain weaves at speed. Raising the forks also reduced the tendency for it to weave when the front end is lighter than normal (humps in the road/throttle pinned/etc.)...

And neck bearing “torque” isn’t a really great way of setting pre-load on neck bearings, but is about the only way to compare being “loose”er or “tight”er than the factory recommendation. Old school is how easy the bars “flop”. Zero resistance to borderline too much resistance made zero perceived difference in back-to-back-to-back-to-back testing (and the bearings came from the factory with plenty of grease-which isn’t always the case with MamaYamaha).

As harsh as the front end is not seeing w/my loading where thicker oil would be a good thing.

Have never changed fluid in an upside-down fork before, next spring I will be figuring it out I guess...

All I have to gamble $500 on a GPR damper is that have read where other people that have had the issue found it helpful-I really don’t want to spend the money on a brand new bike.

[betoney]

35 minutes ago, nhchris said:

Raising the forks reduces the already short  front suspension Trail spec of the Tracer.  Less Trail makes the bike less stable at speed, not more.

Since the Tracer/FJ is quick to turn in in stock form, I am not sure there is any reason for this procedure, especially on a street bike with an already twitchy front suspension.

And, I'd be very curious to know exactly how much weigh gain occurs after an 8mm fork raise. Has anyone every measured the increase in front wheel load after raising the forks?  

You are correct that less trail CAN make the bike less stable, if you go too far in your adjustment, that is why when this has been suggested  (on the FZ/MT/XSR forum as well) to always start small at 5mm and adjust up from there in small increments. 

I have never found the bikes steering to be 'twitchy', with the stock suspension I felt the front end felt light or fluttery under hard acceleration.  When I had the suspension tuner do the original baseline on the new suspension, he raised the ride height on the shock a few millimeters and lowered the front and the bike rides like a dream.  It is VERY stable and I ride a LOT of highway.