High speed shake

[Guest]

I had my ECU done by Vcyclenut. I pulled it out on Thursday morning and sent next day. I paid for express shipping return and to my surprise, it was in my mailbox late Saturday afternoon. I got up today (Sunday) and went out and installed it. I'm actually getting quick at pulling the tank and side panels off. Interesting side note, last month I damaged the ABS sensor and had a check engine light on which I hadn't had a chance to get it to the dealer to turn off. After I installed the flashed ECU, the light is off. Anyway, I immediately had to test it out so I took it out on the highway and let it rip. I had done a Delkovic full exhaust and the bike has felt flat ever since. Flatness is gone. (Is flatness a word?) Nice and crisp like the FZ 09 I rented last month that had a Graves system with a flash. Wouldn't it be my luck that coming out of traffic I ended up behind a Harley with clear highway ahead. Wouldn't you know it, he wanted to get racey and of course as I was testing my reflashed ECU, I was happy to oblige. In the end, flash or no flash it was no contest but I'll give him credit, he didn't back off. This went on for about 5 miles and finally got to my exit which was probably for the best. A mode is now so predictable that I was thinking that there's no need to use Standard mode. I have and still will continue to use B mode in bumper to bumper and city traffic and wet weather. 

I read somewhere that Yamaha has the limiter set at 119 mph because it  gets wobbly at about 115. Sure enough, between 115 - 120 it got real shaky.  I loosened up my grip on the bars and it got better but not gone. I was hitting 125 to 130 and it easily pulls above 100.  I had a 2016 XSR900 and that got wobbly at around 75  to 80 with stock suspension. I have K-Tech on front and rear on this bike (2017) and never had a hint of head shake,  but I never had it over 110. I'm wondering if I can adjust the suspension to get rid of the wobble. It's unlikely that I'll even ride that fast but I'd still like to know that I can pound it out if I wanted without worrying. 

All in all I'm happy with the reflash. I feel like the difference is subtle but it's better. After I did the exhaust I felt like this bike was not pulling as hard as with the stock exhaust and Dave from Vcyclenut said the same thing. I've also read a few other post saying that you loose HP with an aftermarket exhaust without flashing. This seems to be true. The flash fixes that. I think that an exhaust without a flash is just an expensive noisemaker. Isn't that what Harley's are for? The other thing is that I have a problem with authority and having the limiter gone makes me feel whole. I think Flash by Vcyclenut is a good value. Any high speed wobble suggestions are welcome.

[duhs10]

I used Vcyclenut as well.. great value and bike runs wonderfully. Had him set it to start in A mode and never change it. Even in the rain...

[fj09viking]

Had the same issue with wobbles. The change that made the biggest difference for me (still have stock suspension) was raising forks in triple tree. I did 2.5mm at a time between test rides and ended up raising forks 15mm but went back to 10mm as 15mm made turn in tendency a little more aggressive than I liked and the seat angle steeper than I liked for longer rides. That said even 5mm made a big difference.

This bike is susceptible to a lot of things i have concluded, ranging from rough ashfalt (aggrevated by my dual sport tires), crosswinds and especially turbulence from other vehicles. I replaced handguards with bar end weights during the summer and it helped a bit as well in turbulence from other traffic. If I am going straight on fresh ashfalt with no wind or traffic I do not get wobbles anymore after raising forks, but still do in turbulence and/or gusty winds, although only at speeds above 125mph, so I can live with it, as I rarely see that kind of speeds and don't go to the track. Speed rating on my tires are only 130mph in any case.

[Guest]

The wheelbase is pretty short on the pre 2019 FJ 09s and coupled with a crappy rear shock, you have a light front end. Normally raising the forks will give you quicker steering at a loss of straight line stability. I guess raising the forks on the FJ 09 puts more weight on the front end and helps with stability but there's only so much to be gained as you're shortening the wheel base even further.  With the correct shock and spring for the rider and the sag set correctly,  that shifts more weight to the front end resolves shake but at above 115, it comes back. Raising the forks with a correctly sprung and set up bike is not going to give more high speed stability. Even having correctly set up my bike, I'm apparently at the limit of the design. I'm now wondering if a steering stabilizer is the only remaining solution.

[tktplz]

Have you set the tightness on your headset bearings? With the bike on the center stand. Have someone sit back on the bike or on the pillion to get the front tire in the air. Grab the bottom of the forks and lift up and down and see if there is any looseness or clunk. There are also threads on here where people have put different style bearings in the front end. I don't think it's necessary to go that far but repacking the bearings and setting them will probably fix it. Did it to many a VMax with head shake.