XJ900 fork mounted fairing question

I have an '83 XJ900 that has the factory fork mounted fairing. I know that there was a recall on it back then to install or modify??? the fairing to the frame for the obvious stability issues at high speeds.

I want to keep the bike factory original but does anyone know how or where I can get a stable frame mount before I kill myself on the road from the high speed wobble?

I'm sure Yamaha won't help me on a recall of this age. If it requires a totally different faring maybe I'll store or sell the original when I ride.

Any info is appreciated.

 

Europe and Austrailia are the only ones to get the frame mounted fairing, It is totally different than the fork mounted fairing on the one year only Seca 900. The frame mounted fairing is identical to the one on the FJ600.

 

Thanks Ronnie, very interesting. I'll look around for the FJ600 fairing for now.

I have no need to hammer down on the throttle but sometimes I just get the itch to test it. I've been terrified by the high speed wobble a few times and don't like it (super scary).

I guess I will store the fork mounted fairing and pursue a frame mounted for now. Kinda disappointed there isn't an easy way to retrofit the original.

 

Will an FJ600 fairing bolt on without modification? If not, what is required?

 

hey fitz211 what sort of speed are you doing to get speed wobble?
i have an '84 750 the same shape and have managed a 210 k run and didn't get anything in the way of speed wobble, so i am just wondering if you ride may have other issues, ie; tyres, rear shocks/suspension settings,
swing arm bearings any or most of these can and will have an effect on how your ride handles the faster runs. not to mention how good the wheel balance was performed, static/rotation or electronic balance. something for you to consider mate.

 

Good thinking. The wobble has been there since the bike was almost new (late 80's) but happens around 100mph (80-90 if theres wind).

I just got new tires and will be putting the rims back on this weekend. Went a little larger 130-80-18 instead of 120-90 on the rear and 110-80-18 from 100-90 on the front. It's below freezing here now so my test ride may not be a good indicator on performance. I'll look at shock adjustment this weekend too but I think it is at light or medium.

 

Good thinking. The wobble has been there since the bike was almost new (late 80's) but happens around 100mph (80-90 if theres wind).

I just got new tires and will be putting the rims back on this weekend. Went a little larger 130-80-18 instead of 120-90 on the rear and 110-80-18 from 100-90 on the front. It's below freezing here now so my test ride may not be a good indicator on performance. I'll look at shock adjustment this weekend too but I think it is at light or medium.

 

My 900's front-end wobble starts at 117 mph.

That's when the Front Fairing begins to react to the Airstream like a wing.
The curvature from the Headlight to where its anchored at the inside lets the Fairing create lift. But, only momentarily.

The Fairing begins to oscillate.
Acting like a WING it responds to a lower pressure created on one side and moves toward the pressure variant.
That pressure variant quickly shifts to the opposite side as the Fairing deforms creating the variant on the opposite side and causing the Fairing to rapidly sway.

Removing some of the fairings area might reduce the effect.
Venting the outside leading area around the Headlight to prevent the pressure from lowering behind the fairings curvature might help.

 

Yes Rick the fairing is not as rigid as I'd like to see and I think what you are saying is right (my son is taking aviation and just gave me a crash interpretation of what you said). When the wobble starts there is sudden chaos and no time to look around - just to hit the rear brakes and hope to straighten out quick (then clean off the seat).

I put the new rubber on today and went for a test ride. Man was it smooth (choose Avon Roadriders this time). Was a little too cold here to hit the highway so not sure the effect on the wobble.

I like the look of the factory fairing and I will be working on the bike again tomorrow so I will look into venting or more rigid support (w/o hacking it up too bad).

Thanks for the info - what a great source of XJ knowlege here.

 

People complaining about WAY OVER LEGAL speed limits wobbles makes me chuckle a little.

But then again, if I was 20 and single... VROOM VROOM

 

Amazing how we have a higher regard for life and limb as we get older. I know I'm slowing down on the dirt when I get passed by a kid on a 125CC dirt bike!

 

OK guys, point recieved. I bought the Harley because it won't pop a wheelie and I'm just plain on cruisin. Problem is when I get on the XJ it's comfortable, I feel at home, and it just goes a lot faster all by itself.

Fairing will probably stay factory original. I will be law abiding (yes family still needs me). The next owner can fix (especially if he's in his/her 20's).

 

Just a thought...

My XJ550 had an XJ900 handlebar fairing fitted when I bought it, and that too developed a horrific speed wobble at around 90-100mph as I found out to my 'delight' on the ride home. Removing it and putting the chrome headlight back on reduced the wobble slightly but did not get rid of it.
After scratching my head and pondering for a while I tried tightening the headstock bearings. Job done!! Took ten minutes, cost nothing and there are no more wobbles. (fingers crossed.... :? )

 

The frame mount fairing was not done as a recall, it was something that was changed in subsequent years of production as far as I know.

As far a high-speed wobble induced by the fairing.... I know some others have found the wobble, but it's waaaaay up there in mph's. I've been up to 100mph on my 900rk, and I haven't even sensed the beginnings of it. Mine is an 83 with hte fork-mounted fairing.

Best wishes to you.........
Dave

 

I had mine topped out at 135mph many times and there was no hint of a wobble.

 

The XJ900 frame is identical to the Canadian model XJ750RL, in fact, it is an identical bike except for the drive train. The later frame mounted fairing is installed on these bikes, although the bikes themselves are rare by now. This is a toss up with the 900 as my favourite of all the old air-cooled XJ's.

 

The tires I just replaced were shot (Dunlop on the front and a Bridgestone on the rear). I'm hoping fresh balanced tires will help but it will be spring time until I will find out. The bike has never been in an accident...

 

I had a few things cause mine to not handle so well at high speeds

Steering head bearings
Wheel bearings
Front brake setup (new pads on slightly warped discs)

and here's the clincher... Ignition, the back of it where the steering lock is, was rubbing on the part of the frame that it locks against. Tapping a flat head screwdriver between the ignition and the frame with a rubber mallet sorted it out

 

Oh and I have examples of both the fork and frame mounted fairing brackets for the small bikini fairing for the 83 XJ900... Unfortunately I don't have one for sale but I'm gearing up to convert one from forks to frame and can post pics of how it goes... Just not sure when I'm going to get the chance to do it.

I can also compare these two to the larger fairing mount because I have a couple of them too

I'll be back

 

Thanks Alive, I would be interested to see how Yamaha overcame the feat to frame mount the small fairing without compromising the original design and appearance too much.
I will be replacing the rotors and pads before spring but it is way to cold here for me to even walk out to my garage right now.