Head shake experience.

[redfjniner]

I left two weeks ago on a 14 day ride to Colorado with 4 friends. While riding in Oregon on US 395 just south of Ukiah, OR, I developed a head shake. It was scary and I believe that if I hadn't had the GPR4 installed it would have gotten out of hand. Note:  I have done this before without issue.  Here are the facts:
 
1. The bike had 19,000 miles on it. (22,000 now)
2. I had FJR side cases and they were full. Each weighed around 35-40 lbs with contents.
3. I had a tail bag that weighed around 20 lbs with contents and a tank bag at about 10 lbs.
4. I had brand new Dunlop Roadsmart II's front and back. I had pumped them up to 39 front and 42 rear.
5. I also had a 2L water jug mounted to the right saddle bag bracket that was full of water.
6. I weigh 160 and with my gear on it would make me around 175 lbs.
7. I have HVP heavy weight bar ends, which were installed just before the trip.
8.  GPR4 setting was at 6, I increased it to 11 after this.
 
Coming out of a 40 mph corner at around 75 into a straight, I accelerated to 110 mph (STD mode) at which time the head shake and rear started to go wild. Each going in the opposite direction as the other. This was my first experience with a head shake after over 360K miles. I let off on the gas and coasting to around 80-85 before it stopped. Not sure what started it and have concluded it may have been a combination of things, such as: Road surface, to strong of grip on one or both of the hand grips, and shocks getting worn out are my best guesses. I did not stop and investigate the road surface. I made it a point to not do that again on this trip, although I did go over 100 on a number of occasions and there wasn't any indication that this was going to happen again. Yamaha may have some inside info. for their reasons to publish instruction to not exceed 85 mph and not to use both top box and saddle bag, as well as using smaller side bags so you can't load them up so much. Be careful, just because you have done it before without issue doesn't mean it won't happen.

[wessie]

That's a lot of weight on the rear - I kept my panniers down to 10kg each, around 22lb on a recent long trip.
 
With other factors that you mention, that has to be a significant element.
 
When I saw the subject line, I thought this was going to be the tale of how you broke the leg. Hope you have good drugs and are on the mend.

[mhevezi]

On my old SV650S, I had nasty headshake with the stock Dunlops- just about everywhere. When I put Michelin Pilot Road2's on my SV, the headshake went away entirely. It was amazing how different the bike felt.
 
Sounds like you hit the right combination of weight, speed, road surface & balance that introduced the shake. I'd be surprised if it happened again, under "normal" conditions.
 
My advice is to keep it under 100 when you are loaded up like that!
 
Glad it didn't get worse and you were able to keep the bike up.

[cobby7]

Your front tyre is overinflated if you are really running it at 39psi. Should be 36 

[Guest branthopolis]

Your front tyre is overinflated if you are really running it at 39psi. Should be 36 

That seems to be a highly contested statement around here, but I'm with you..   I run 34 ft / 36 rear..   I've adjusted my suspension on the firm side because I ride pretty hard.  I have side bags and a top case mounted 100% of the time..  I've run it up to 115 mph (limiter) with no headshake issues..  I do get buffeting when I'm riding anywhere near another vehicle at highway+ speeds, but when I'm in clean air, the bike is as stable as can be.  I might get slightly less mileage out of a set of tires, but in the big picture, the increased stability and traction is more than worth it. 

[fanowater]

Sounds to me like the front end got light and the rear was sliding a little. Put the two together and you can have all kinds of fun. Glad you kept it upright.
Due to your experience I assume you adjusted the shock for the extra weight, but I don't think the stocker is any good. So when you heal up (read your other post - bummer) I'd get a better rear shock able to handle your riding style and I'd do my best to cut the weight down in back. I highly recommend the Penske 8983.
 
Cheers

[fjay09]

I experienced this for the first time on the FJ today. Made a run on my lunch break to a store to look at a safe. Was going about 75-80 mph when it just came out of no where and the front end started shaking. It was cool out this morning so I had on my leather Icon jacket instead of the mesh one. This is only my second time riding the FJ with this jacket and it feels different since the wind is bouncing off not going through the jacket. I have cortech bags on the back but they were empty. Maybe it's time to invest in a GPR4?