Hyperpro Fork Spring?

[Xman]

Hey all,

I'm finally getting to my upgrades before spring hits in the north. I attempted the Fork Spring swap with out changing the oil(I know). I measured a few things before and after. I've read about sag and such but probably not checking it quite right. Anyways, I put zip ties around the fork and sat on the bike, got off and checked the distance. It was around 3/4 inch. After installing the springs doing the same test yielded the same result but raised the front by 1/2 inch. From what I've read it seems one should lower the front-end. I lowered it about 1/2 inch. But now I barely get any fork compression when sitting on bike. Would this make sense?

My next thing is to shim the rear by 6mm and see what happends.

Maybe that will put more weight on the front? Unfortuanately I can't get out to do any test rides.

Can anybody who has done the Hyperpro fork spring install give me some help as to what they did.

What about the Fork Cap? It was a bitch to get back on. How do you know how far to screw the cap onto the rod? Is it all the way till it stops or do you modify this and then set the lock not below it?

This is on a 2003 bird and I weigh around 185 with no gear.

I know this is a cluster of questions...

Thanks... Jeff

P.S. Wish I would of waited for this suspension group by... May still get the rear shock though.

[Helvet]

Hi Jeff,

here in Holland by far the most riders have switched to Hyperpro springs front and rear. They are awesome! However, the springs are longer than the original ones, that is why it's hard to get the caps back on....

You need to turn the caps fully, untill the end!

Also they recommend thinner oil in the shock 2.5 or 5. I know it sound weird, but it works very well! You cant get any fork-compression because the spring is much stiffer than the original. Honda used really thick oil to stop fast travel of the fork, but in reality you need that. So change the oil...

Further more you need to lower the front through the yokes by an extra 1.5 inches. Because the spring is longer, and it gets stiffer all the way you can do that without compromising ground-clearance.

Also you should lift the rear by using some spacer-rings by 5mm (about 1/5 Inch). I do recommend a Hyperpro spring in the rear as well, although the difference is less than at the front.

With correct installment you can corner a lot faster (even up to 50% on bad roads), and get more stability and comfort.

[Northman]

Further more you need to lower the front through the yokes by an extra 1.5 inches.

I STRONGLY advise against this advice. Lowering the front end that much will cause front end instability, and cause the front end to bottom out (fender to lower triple clamp) under load.

With correct installment you can corner a lot faster (even up to 50% on bad roads), and get more stability and comfort.

I doubt that much improvement, as well.

If that were the case, Honda would install these springs, and sell the XX as a race replica :roll:

[Helvet]

Ask any of our Dutch members if I am exaggurating (how do I spell this?). This really is the truth!

This 50% is the max on bad roads. On good roads the difference will be like 10% (just an educated guess..)

Every Dutch rider who uses Hyperpro's have lowered the front this much, and raised the tail. It really works very well. The bike feels a lot lighter cornering, without losing stability.

The bike is still so stabile, I can stand up on the footpegs without holding the clip-ons, and make my (shallow) corners. Most riders in Holland have seen me do that.... However, I must say that the tires also contribute to that. I would not try this with the Bridgestones.... (I use Michelin now).

[Xman]

I lowered the front-end the same amount it was raised, so I should be back to the original dynamics. It was about 1/2 inch.

As far as the oil goes, Hyperpro sent me 7.5wt oil. Which I think is wha tis in there now, so I didn't bother with changing it at this time.

I know the springs are stiffer but should I worry about the sag factor? Should I go back and get some spacers and cut so it matches the original lengths of the spring and spacer?

Warmer weather is on the horizon and itching to get this straightened out..

[Warchild]

Helvet, are you sure you don't mean 1.5cm, and not inches?

1.5cm is .59", which is more reasonable than 1.5". I agree with Northman, 1.5" seems pretty excessive. Dropping the triple tree that much has *got* to cause clearance issues over rough roads, and definitely affect steering geometry to a large degree.

However, your comments about using much thinner fork oil is echoed by Wilbers, who initially told me to use 2.5wt oil when installing their fork springs. The factory oil (HondaPro SS-8 ) is 10wt, so using oil 1/4 of that viscosity really caused me to raise an eyebrow. I have asked them to re-confirm to ensure that's what the Wilbers factory really recommends. I believe the Wilbers springs, like the HyperPros, are a bit longer than stock springs, so this thinner oil recommendation would be consistant with what both companies suggest.

[Xman]

So, by changing to 2.5wt oil will that increase my sag as it's next to nothing right now.

I agree lowering the front-end by 1.5 " is a lot. The fork tubes would be sticking way up. Like I say I lowered mine 1/2" to get back to square one on the height.

[Helvet]

I really mean 1.5 Inch (for us 4 cm) dropping the front end. My bike was the test-bike for our comparison test almost 3 years ago. It was set up by the Hyperpro factory-mechanics. I guess they know what they are doing...

If you are worried, why not start with half of this? And then adjust untill you are satisfied.... It takes about 3 minutes each time, so not really a problem.

I am a little worried for my Superbrace (not yet installed, returned to the factory), because this might give me a clearance problem because we dropped the front so much.....

I guess the Wilbers uses the same springs as Hyperpro do, because it is a patented system to produce these springs. the 2.5WT oil is really very thin, but it works very well. You feel a lot less bumps in the road, but it still feels like there is a lot of damping. The big problem with the original setting Honda uses is that the bike really jumps up and down on fast bumps....

WP (White Power from Holland) use 5 or 7.5WT in their set-up.

[Helvet]

I just went outside, and measured the height the forks are sticking out of the Yoke. I was indeed mistaken..... Sorry for this.

The top of the forks are 5 cm (2 inches) above the yoke. On top of that you got the fork-caps. I don't know what I was thinking before (or why...).

Sorry for the confusion!

[Northman]

Factory is 39mm, so you've dropped your front end 11mm.

That's a more reasonable number.

[demon]

That makes more sense Helvet. I wouldn't recommend lowering over 1/2" for clearance issues. 6mm (1/4") on the fork usually is enough to feel the difference in handling.

[Xman]

Keep in mind though that after installing the Hyperpro springs it raised the front end up about 1/2". So lowering 1/2" gets you back to stock height then I suppose you could go more for the handling part.

Helvet, how much sag to you have with this setup? When I lowered the front-end that 1/2" it put more weight on the front and I lost my 3/4" sag. Now it's next to nothing. What would be my next steps in getting a correct setup? Will adding the thinner oil change the sag or is that done by the spacer in the fork tube? Did you stick with the stock spacer?

Thanks, Jeff

[demon]

Your fork oil won't affect sag numbers. The spacer for your preload on the spring will affect your sag. The oil in the fork just controls the ocilation of the spring's up and down motion. The spring holds the bike up. I'd get the sag right and then worry about chassis attitude. Keep in mind though, the forks don't care where they are in the tripples. Landing a good wheelie will still compress the forks and they don't know you've effectively taken 1" from the travel. The fork stroke is in the lowers and if you lower the tubes in the tripples too much, then you run the risk of your lowers making contact with the lower tripple clamp in extreme situations.

[Helvet]

Keep in mind though that after installing the Hyperpro springs it raised the front end up about 1/2".  So lowering 1/2" gets you back to stock height then I suppose you could go more for the handling part.

Helvet, how much sag to you have with this setup?  When I lowered the front-end that 1/2" it put more weight on the front and I lost my 3/4" sag.  Now it's next to nothing.  What would be my next steps in getting a correct setup?  Will adding the thinner oil change the sag or is that done by the spacer in the fork tube?  Did you stick with the stock spacer?

Thanks,  Jeff

I don't really remember if they left the spacer in. If I have to guess I'll say that they left it in (it was almost 3 years ago...).

Do you mean by the sag how much the front end drops if you sit on the bike? This is not much, about 15 mm....

If the bike is not loaded, and stands on 2 wheels, you can still lift the front end for about 15mm untill the forks reach the end-stop.

[RodeRash]

So, by changing to 2.5wt oil will that increase my sag as it's next to nothing right now.  

You are talking about two different things here. You adjust your sag by changing the length of the spring spacer. Sag should be about 1/4 of your entire suspension travel. (about 1 1/4 inch)

On the blackbird, Honda set the bike up with soft springs, but a lot of compression damping. Thinner oil will reduce the compression damping, but it also reduces rebound. It's probably best to work with one of the suspension companies to get your damping configured correctly.

However, having the proper weight springs, and the correct sag is a good start to a better handling bike.

[Xman]

Just called Hyperpro on this as I didn't get install instructions on this. They recommended cutting the spacer to equal the original length of the original spring and spacer. They still recommended the 7.5wt oil they sent me. Is stock weight 10 or 7.5 for an 03?

I'll go back to square one and start with cutting the spacer.

Now what to get for a new spacer instead of hacking the original one? :-D I wonder if they have that same size medal spacer at Home Depot?

I think I'm understanding more of this now. :roll:

[Guest rockmeupto125]

Jeff...........you can use plain old white PVC tubing, schedule 40. A jig or table saw cuts it handily. Just use a rasp to clean up the shards from the ends so the oil doesn't get debris in it.

[wadem]

When I got my springs last year they sent me 2.5wt oil. I wonder why the change? I ended up using 5wt anyway as I didn't like the sound 2.5wt made.

[erixx]

i specially didn't like the 2,5 oil when i nearly crashed at a highspeed roadhole, i think the spring was way to quick back... Now i use 7,5 oil. its LESS conformtable, but FASTER :-)

BTW, instead of lowering my front i have really got my rear highter ( 9 mm spacer) No more fairing scratching,...