My friend is the one who recorded this video. He wound up breaking some ribs, his hip and his collar bone. The rider who crashed sold all of his gear last week and has given up riding. =(
From my measurements, the 919 grounds out at roughly 50 degrees of lean in stock form with the hero blobs removed. It's significantly less than what the average track bike achieves. How exactly did you set up the 919 to be "tall?" Or rather, what are some go-to mods for better track performance? To be honest, I don't believe my honda with stock suspension and 60k miles could even handle the increased energy from higher lean angles. It already feels like it's being twisted into knots if I'm not ultra smooth. God forbid I hit a dip mid corner, the rear shock pumps a good 3-4 times before it settles out, and thats with the rebound full hard. My guess is a cartridge kit, a good rear shock and a good set of rearsets + trackday rubber would greatly benefit the bike. Then again, for the same price you can just buy a track-ready sportbike which will easily outperform what I just suggested.
#1 by far is hearing about the injuries, but hopefully that hip mends nicely, and my guess is that it's been fastened together.
#2 is a reply to your other points, trying to keep it short and sweet.
919 re 50 degrees of lean
I donít know how you derived that number, by static measurements (a flawed approach as doesnít included suspension loading from the turn), or other means, perhaps off of a fixed mount camera?
Anyway, somewhere in the low 50s is what Iíd guess at for a riding limit.
As in being on an UJM with tires more capable than the bike with mere mortals riding it.
Iíll bet most Group 2 track day bikes never see 55 degrees.
Just look at the respective tire contact areas and their levels of wear for comparison.
Personally, I try to use as few degrees of lean as I can for any given speed and radius of a turn.
Ultimately, a 919 is no super sport and canít be made into one.
But a well set up and well ridden 919 is no slouch in the right hands.
Keep in mind also that when you get into the 50s, your overall ďsuspensionĒ becomes very reliant upon the tire, so if you donít have a tire designed for such a lean angle, and donít pressure it properly, you wonít get the required tire suspension effect to compensate for the loss of suspension effect at the forks and rear end because of the high angle of lean.
Re a Tall Set Up
It means the chassis ride height has been increased (to elevate the C of G) while still using a good spring rate with a good amount of installed preload, and maintaining good front end geometry.
In the case of a 919, it also alters the unlinked swingarmís angle enough that the net squat is reduced.
I use an adjustable length rear shock to deal with the rear end.
Iíve been forced to wind in the ride height adjusters all the way, and there is a sacrifice of compliance near full fork extension doing this.
Iíve also dropped the tubes a bit in the clamps a bit to get the front end where I want it.
This winter I will fit a set of custom made extended fork caps that I already have, and then not need more than a ring of front end ride height tinkering range, by playing with tube drop in the clamps.
Re Stock 919 Suspension
What you describe is less than no surprise.
The front is better than the rear.
2004+ are worse than earlier, because of the mush rear spring rate.
They are also squat meisters.
If you can find LDHís writeup of years ago that was on 919.org, see how even with the stiff rear spring of his 2002 still resulted in serious swing arm yo yoing at pace under certain condition.
The rear rebound adjuster on the 2004+ is pretty much for looks in my mindÖÖÖÖÖ..
Re Upgrading 919 Suspension
Front end: proper springing, valving, low speed compression bleed porting, shimming, oil level, and installed preload.
Rear end: Adjustable length 3 way adjustable shock with digressive compression piston facing, properly sprung, properly setup re soft top out if said shock has no internal soft top out.
Rear sets: optional, but a good idea as no levers will grind and more importantly, no extreme foot repositioning will be necessary to keep oneís inside foot from getting crushed by the folding stock peg.
Tires: dedicated track day tires are a mistake on a street use bike also being tracked, race tires even more so. Further, using Dunlop as an example, what really is the best choice? Q3+ or Q4? If said tire is to see cold wet early and late season use, Iíd go Q3+ and give up the track only displayed superiority of the Q4.
Re Track Ready Sport Bike
A dedicated track day super sport bike is fantastic.
(Especially a good well built, well set up, and well maintained retired race bike.)
But if one canít have one, and has an UJM they love and want to keep for Universal use, then there is less than nothing wrong for using a 919 at track days, be it stock or upgraded.