Wobble and Weave

[FJ1200W]

Here is a link to a great old video that's worth watching IMHO.

It has several classic motorcycles, but more importantly, gives a simple solution to the "tank slapper".

https://www.youtube.com/watch?v=z3OQTU-kE2s

[andyoutandabout]

There you have it; scoff choccy eggs and drink beer over Easter. Remain on couch.
By summer you'll emerge a confident high speed rider, but stairs might be more of challenge.

[red]

Here is a link to a great old video that's worth watching IMHO.  It has several classic motorcycles, but more importantly, gives a simple solution to the "tank slapper".
https://www.youtube.com/watch?v=z3OQTU-kE2s

FJ1200W,

Man, I disagree with this guy in the video, by a lot.  That serious malfunction is NOT some natural and unavoidable occurrence, like hail.  What we see in the video is an engineering failure, either by the bike maker or the tire maker, or both.  As for lying flat on such a machine, uncontrolled and at high speed, that takes a level of guts which may be rare, even among experienced riders.

On other bike forums, there has been some discussion on this issue.  In almost every case, changing the OEM steering head bearings over to tapered roller bearings has fixed the problem completely.  Occasionally, a tire which is defective in some way, by poor manufacture or odd wear patterns, can be the cause.  The right choice for the front tire then can be the good "fix" in some cases.  I would want the better steering head bearings anyway, in whatever bike I ride, as a first option.  I don't know if a faulty rear tire could cause such a problem, but I would not rule it out, either.

For the larger bikes, it might be worthwhile to switch to GT (or other heavy-rated MC) tires.  Changing from conventional street tires to Pirelli Angel GT tires gave me a completely new and different bike, over the previous tires.   With those Pirelli tires, the handling was greatly improved, far beyond the usual good feel of new tires.  The confidence they gave me was amazing.

All IMHO, of course . . .
       
.

[T Legg]

I think this video illustrates why most of us choose to have a moderate pot gut.

[Sparky84]

For the larger bikes, it might be worthwhile to switch to GT (or other heavy-rated MC) tires.  Changing from conventional street tires to Pirelli Angel GT tires gave me a completely new and different bike, over the previous tires.   With those Pirelli tires, the handling was greatly improved, far beyond the usual good feel of new tires.  The confidence they gave me was amazing.

All IMHO, of course . . .
       
.

Red, I take it that you have a 17" rear.

What's the mileage you get on them Red?

Cheers
Alan

[PaulG]

Did they get hazard pay and free diapers?

I've only had that happen once. That was on my first bike - 1982 Yamaha 750 Seca. (bought in 85)  Slowing down for an off ramp and got a tank slapper.  Proved to be worn steering head bearings.   IIRC they were OEM ball bearings, and I switched to tapered.

I never experienced that on my 1978 BMW R80/7. BUT  I bought that in '89 with only 1600km on it. First year I rode with the original tires,     2nd year I got a set of Dunlops.  It had stock OEM tapered bearings in the steering head. Had it for 8yrs without a problem.

This video was from '76 (?), so I would put it down to  mostly "shitty" '70s tires/tyres, then chassis.  This was a time IMHO when engine development was leaping years ahead of tire/chassis development. Especially when you look at the Japanese engines vs their spaghetti frames of that period.  It wasn't until Suzuki came out with the GS series after '78 that things improved on that end.

If any of the elder statesman of this site who worked on these bikes at that time could chime in.  This is what I absorbed through osmosis from older brothers who rode during that time, on these types of bikes.  But I never recall them talking about wobbles like this.

[red]

For the larger bikes, it might be worthwhile to switch to GT (or other heavy-rated MC) tires.  Changing from conventional street tires to Pirelli Angel GT tires gave me a completely new and different bike, over the previous tires.   With those Pirelli tires, the handling was greatly improved, far beyond the usual good feel of new tires.  The confidence they gave me was amazing.  All IMHO, of course . . .

Red, I take it that you have a 17" rear.  What's the mileage you get on them Red?  Cheers
Alan

Alan,

I haven't finished them off just yet, but I'm guessing ~7k~8k for mileage.  For the great improvement in handling, though, I wouldn't care at all about the mileage they give me.  They are really THAT good.  Life is too short to run on cheap crappy tires, especially lately.  I ride for FUN!

Yeah' 17" wheels, on my "other" bike, my FJR1300.  The FJR is about 50 pounds (~23kg) heavier than my FJ1100, and I'm no lightweight guy, either.    

Point of interest, I run 16" Pirelli Sport Demons on my FJ1100, and they are the best tires I have had on that bike, for handling.  Those tires are not near finished, either, for mileage.
.

[giantkiller]

I had a speed wobble on my 87 fzr1000. It would start at 128mph. If you accelerated slightly it would go away at 135mph. I checked everything I could think of . Steering head tension. Tighter looser. Still there. Checked the tire looked good. Bearings looked good. ECT ECT. Couldn't figure it out. Finally replaced.the front tire. And it was gone. Tire looked great. Fairly new.

[Bozo]

I had a speed wobble on my 87 fzr1000. It would start at 128mph. If you accelerated slightly it would go away at 135mph. I checked everything I could think of . Steering head tension. Tighter looser. Still there. Checked the tire looked good. Bearings looked good. ECT ECT. Couldn't figure it out. Finally replaced.the front tire. And it was gone. Tire looked great. Fairly new.

Having a Z1R 78 mode;, I had my share of high speed wobbles, worst was going around a slight bend at 170kph and accelerating, my back wheel was bouncing. The bike was fairly new and checked beforehand. When this happened the third time I modified the steering to tapers and strengthened the frame. I would never go back to a standard frame after this. I had a MachIII before that , a H1E I could ride the hell out of that bike and the worst I got was a mild head shake.
Agree with one thing, when I had panniers and a tent etc on the back the bike was magic (for its time).
Now I have 2 FJ1200 as well, these would have to be the best handling older bikes (read big/ heavy) I have ridden apart from the GS1100.

[Sparky84]

For the larger bikes, it might be worthwhile to switch to GT (or other heavy-rated MC) tires.  Changing from conventional street tires to Pirelli Angel GT tires gave me a completely new and different bike, over the previous tires.   With those Pirelli tires, the handling was greatly improved, far beyond the usual good feel of new tires.  The confidence they gave me was amazing.  All IMHO, of course . . .

Red, I take it that you have a 17" rear.  What's the mileage you get on them Red?  Cheers
Alan

Alan,

I haven't finished them off just yet, but I'm guessing ~7k~8k for mileage.  For the great improvement in handling, though, I wouldn't care at all about the mileage they give me.  They are really THAT good.  Life is too short to run on cheap crappy tires, especially lately.  I ride for FUN!

Yeah' 17" wheels, on my "other" bike, my FJR1300.  The FJR is about 50 pounds (~23kg) heavier than my FJ1100, and I'm no lightweight guy, either.    

Point of interest, I run 16" Pirelli Sport Demons on my FJ1100, and they are the best tires I have had on that bike, for handling.  Those tires are not near finished, either, for mileage.
.

Thanks Red,
I've been running the Sport Demons for a while now, they are good and usually average about 10k (kilometres) out of them and I need a new set before rego, also usually do both at same time.

Thinking of changing to 17 on front and 18 on rear and the Angels come in an 18 too.

Cheers
Alan

[FJ1200W]

I think this video illustrates why most of us choose to have a moderate pot gut.

Mine was gone and I thought I had a win,
But thanks to the "Stay at Home" order -
It's getting larger again,
Right at the border......