Originally Posted by Ferris Bueller
The well known weak link on a 919 is the frame, swing arm, and suspension. The suspension is easily fixed with a rc51 fork swap and ohlins bits. Then the only short fall with the suspension is the lack of progressive linkage.
My questions are :
Has anyone swapped swingarms with a cbr and retained the linkage?
how would someone beef up the frame?
The nonsense about the 919 frame is that and nothing else but.
I have 2000 km of track time on my 919.
The frame is more than adequate for street tires on the track, case closed.
What needs improvement is the suspension components if the bike is going to be pushed and the rider wants some predictable chassis margin.
Even the swing arm is OK, the pogoing is squat and shock related.
The swing arm angle is too flat.
So with an aftermarket shock you can lengthen it , which does two things.
You reduce the net squat force and reduce the force needed to get the bike leaned over. (raise the front too)
There's a Brit on the site that grafted a linked swingarm on, can't remember the details but it can be done - but you lose being able to use the Y tube so must go to a side mount 4:1.
A prepped 919 front end or prepped F4i front end will be better than a stock RC51 front end.
A prepped RC51 front end will be better yet.
The 919 front end is adequately stiff.