There's every possibility you'll be in trouble withing minutes, do you really want to find out as you hit a bump or brake form 60mph?
Gnasher, I am NOT going to be riding with that PVC tube and washers in place!!
I am going to cut a couple of lengths of it, take out the OEM spacer, put in the PVC and washers and *sit* on the bike so my GF can measure the sag.
Then I'm going to tweak the length of the tube or add or take away washers until the preload is correct to give me the right sag.
Then I'm going to put the spacers back in until I can get a set of metal ones made up.
Clear?
The point is that the progressive spring is already being compressed somewhat by the spacer, which is why the sag is out.
By shortening the spacer, fewer of the spring coils are being squeezed down, thus giving more sag.
Yep that's why I've suggested putting the standard springs back in they're 10-20% less than Hyperpro and the sag will be much closer if not correct and it's your dampening that's wrong, not the springs
Damping controls the *rate* at which the spring moves, yes?
So with no damping, the spring would bounce up and down until it runs out of energy. The thicker the oil, the more slowly the fork will move.
But it is not the oil that is holding the bike up, it is the spring. The softer the spring, the more it will sag, yes, of course and vice versa, but also, with a softer spring, when the fork is under load the fork will drop more.
As I've already said, with the Hyperpro springs and their 15W oil, I am using about 80% of the fork travel under hard braking. A softer spring would mean that the fork travels further and risks bottoming out.
Changing the oil will only affect how quickly it gets to the bottom.
I'm talking about shortening the spacer which compresses the spring.
the standard spacer is such that the spring is almost at it's non compress length
Yes, but I'm literally talking about changing the length by a few millimetres, not even the full 10mm that the Hyperpro bloke said.
I unscrewed the fork cap by about 7.5mm which gave around the right sag (or possibly a little more), so I'm going to try the PVC tube and washers about 5mm shorter than the OEM spacer and see what that does.
it's the Hyperpro spring that's wrong, it's too hard for your weight, so whatever you do to it, it is not going to change it.
Well if it is, I'll have to get another one, but I'm not currently convinced that it is.
There is no shim pack on the FZ6 forks.
Yes there is, it's inside the damping rod.
As far as I can see, the damping rod is just a tube with a hole in it. The FZ6 has cheap suspension!
Err, as far as I'm aware, the air gap above the oil level has nothing to do with the preload!
We all learn something everyday
Well, I've seen nothing to say that the air gap has anything to do with the preload, but I'm willing to be corrected.
As far as I can see from pages like this, the air gap is there to stop the suspension bottoming at the end of the stroke:
Oil Level
A change in oil level will affect the air compression; it does not affect damping. However, too large an air gap in forks may cause forks to dive too fast. Conversely, if the oil level is too high with too small an air gap, it can have a significant effect on the last bit of fork travel.
http://www.promecha.com.au/damping_oils.htmI can see nothing there that refers to preload which is how much the spring supports the bike and rider in its natural equilibrium.
To directly quote a guy from Hyperpro:
The oil level determines how much the fork goes "in" when you brake hard. So changing the oil level, does nothing when riding normal.
He needs to be working somewhere's else then.
Gnasher, I know you're trying to help, and I appreciate it, but, with no offence intended, I have one opinion from a bloke who works for a major suspension manufacturer and another from a bloke on an internet forum.
So if there's a reason why your opinion is better than his, I'd welcome hearing it.
Adding/removing oil (changing the air gap) is just a cheap basic air spring i.e. preload.
That is using the word "preload" in a way that I have not seen used elsewhere.
Preload controls the amount of "push" that gets the spring moving. The more preload, the more push is required before something happens.
For instance this site says "If your sag figures are too small no matter how much preload you take out, that’s a sure sign that your springs are too stiff."
https://www.motorcyclistonline.com/making-sense-motorcycle-suspension-springs-tech-tips-mc-garage-technology/Now, as mentioned, if I unscrewed the fork caps by 7.5mm, it gave about the right level of sag, or perhaps a bit more. But that has nothing to do with the oil level.
I'm quite willing to take advice if it benefits me, but what you're saying appears to be contradicting what I've had from Hyperpro themselves or watching eg Dave Moss's videos.
Mate, what you're doing is trying to rectify one mistake (fitting higher rated springs) by making and even bigger one. The advice given hear is given to stop you 1 potentially, seriously hurting yourself or wrecking your bike, 2 to help you solve your problem. If you don't to take it happy days, as I said earlier "it's your life" and you may well get away with it, lets hope you do.
But, with respect, what makes your advice better than that I've had from Hyperpro or heard from Dave Moss videos?
I want to get this stuff right, so if I'm going to listen to you, rather than them, please give me a good reason to.