85 FJ1100 Front End Issues

[Burns]

[

+ 2 the FJ is the most stable motorcycle I've ever ridden.

[FJ_Hooligan]

Out of ALL the times I experienced a front end wobble a new front tire cured it EVERY time.

[mr blackstock]

G'day,

I have an 85' also.  When I get front end wobble, I first check tyre pressure, then tighten steering head bearings.  Real easy job and cures "the wobble" too.  A square tyre will feel really flakey over uneven surfaces. 

Best way to check if it is steering head bearings without dismantling?  While riding, decelerate and remove both hands from handlebar, keep them close 'coz if you start to get head shake you can put your hands back.  No head shake?  Bearings are sweet.

Just my experience..

cheers, Gareth

[Burns]

4-sure if the steering stem bearings are loose you will get a scary progressive weave "hands off" when decelerating.  But if they are too tight you can get a slow weave at moderate speed (say 30-40).  So, you need to get in the Goldlocks zone (just right).

A  set of "All Balls" tapered bearings is a 25 dollar investment that I strongly suggest.

With bearings of unknown condition you will be looking for a notchy feel, or a "home base" (where the forks seem to want to stay) as you turn the bars through their arc with the front wheel off the ground. Anything other than a smooth travel through that arc indicates a bearing problem (clean/lube/or replace).

If all is smooth, the drill is to set the bearing tension so that with the front wheel off the floor and pointed straight ahead, nudging either handlebar-end slightly will cause the wheel to flop over gently and fall to the steering stop.

If it falls quickly and slams into the stop, the bearings are too loose. If it falls sluggishly the bearings are too tight.

Once you get the bearing tension in the ballpark, put some miles on the bike and then check them again.  Of course if you experience a wobble "some miles" means until the wobble.

It is not unusual to have more than one cause to a problem, but this is one that is easy to eliminate

[ribbert]

If all is smooth, the drill is to set the bearing tension so that with the front wheel off the floor and pointed straight ahead, nudging either handlebar-end slightly will cause the wheel to flop over gently and fall to the steering stop.

If it falls quickly and slams into the stop, the bearings are too loose. If it falls sluggishly the bearings are too tight.

Burns, I've always had a bit of a problem with this method. It is compromised by hoses, wires and freshly packed bearings and usually differs from left to right. I believe it to be an unreliable indicator, as are other recommended methods such as a torque value, not so much the torque value itself, but the practicality of accurately applying it.

I use the same simple adjustment method that is universal (and what I was taught in trade school)  for tapered front wheel bearings on cars, nip it up until is is "seated" and back it off a whisker.
I have never had occasion to believe this gives anything other than a perfect adjustment for tapered bearings.

Just another opinion.

Noel

Usual disclaimer

[Burns]

True enough, Noel. Though the method I describe is pretty much "old school" standard it does assume that the front end is not encumbered.

I think that using either technique most folks will get a base line and will generally need to tweak it a bit to get everything "sweet". Bearings sometimes seat a tad, which loosens things up. You may be compensating for that, with the benefit of a sophisticated touch.

It's pretty subjective, and I suspect that you are getting it right the first time now because with your experience you have developed a feel for it.  "muscle knowledge" cannot be taught any way other than experience.

just my opinion too, of course.

[bigbore2]

Just to mention it, as no one has yet. Tire pressure up front MINIMUM 38 lbs. Those of you doing the twists probably like a little more?

[ribbert]

Just to mention it, as no one has yet. Tire pressure up front MINIMUM 38 lbs. Those of you doing the twists probably like a little more?

When attending a Californian Superbike School day, two guys with a compressor walk up the entire line of bikes at the start of the day and lower everyone's tyres to 30 psi.
Like most race tracks Philip Island has the usual mix of very fast and very tight corners.

Noel

[racerrad8]

When attending a Californian Superbike School day, two guys with a compressor walk up the entire line of bikes at the start of the day and lower everyone's tyres to 30 psi.

Noel

Sorry, I just have to ask...

Why do they need a compressor to lower tire pressure?

If you are riding a stock FJ, you should follow Yamaha's recommended tire pressure settings.


If suspension modifications have been applied to the bike, then you need to check with them and see if they have different pressure setting in place.

I know RPM has different pressure recommendations based on installed RPM components.

Randy - RPM

[the fan]

Just to mention it, as no one has yet. Tire pressure up front MINIMUM 38 lbs. Those of you doing the twists probably like a little more?

When attending a Californian Superbike School day, two guys with a compressor walk up the entire line of bikes at the start of the day and lower everyone's tyres to 30 psi.
Like most race tracks Philip Island has the usual mix of very fast and very tight corners.

Noel

What tires were they running? We run 30fr, 26rr cold on Dunlop Q3's. This is for track only as you build up a lot of heat in a track session.

A lot of tires vary on the optimal tire pressure but 36/42 is pretty common for sport touring rubber (radial). A good starting point if you really want to dial in a set of tires is by comparing cold and 'hot' pressures.

To do this measure the pressure in tour tires cold. and then ride the bike as you normally ride for about 30 minutes and recheck the pressures. you should see a gain of 10% front and 15% rear if you are running radial tires (10-10 for bias). These formulas were given to me when I was running a shop by more than one tire mfg rep and have proven to be reliable.

On an unknown bike or tire I generally start at the lowest recomended pressure and calculate/adjust from there.

basically if you start at 32psi cold you should see 35.2psi hot front and 36.8 rear. if you see a gain of more than 10%fr / 15%Rr you need to raise the starting pressure. Less, you need to lower it.

Running lower pressures/ higher gain will give more traction at the expense of tire life and is common for track day users. Running (slightly) higher start pressures with less pressure gain gives better mileage at the expense of grip and ride quality

I am sure someone will claim I am completely wrong and that wiki discribes the physics differently, but it works for this hilbilly and will likely work for you as well.

[ribbert]

When attending a Californian Superbike School day, two guys with a compressor walk up the entire line of bikes at the start of the day and lower everyone's tyres to 30 psi.

Noel

Sorry, I just have to ask...

Why do they need a compressor to lower tire pressure?

If you are riding a stock FJ, you should follow Yamaha's recommended tire pressure settings.


If suspension modifications have been applied to the bike, then you need to check with them and see if they have different pressure setting in place.

I know RPM has different pressure recommendations based on installed RPM components.

Randy - RPM

Haha, I knew someone would pick up on that, I asked the same question. It's for the surprising number of riders that turn up for the day with less than 30 psi. He told me some arrive with tyre pressures in the teens.
This was level one and a lot of the participants were not seasoned riders. They get answers like " how could that be, I had it serviced last year" etc.

I test rode a bike I was intending to buy recently, it rode like a truck. The particular model has a tyre pressure monitor on it (no excuse) The tyres were both just above 20 psi on a 1200cc bike. I pointed this out to the owner who just gave me that "so what" look. It was a BMW though and hence, a BMW owner!

Noel

[Burns]

Thank you "the fan" I cut and pasted your comments and put them in a notebook of m/c info
that I keep