Welcome to Netrider ... Connecting Riders!

Interested in talking motorbikes with a terrific community of riders?
Signup (it's quick and free) to join the discussions and access the full suite of tools and information that Netrider has to offer.

Rank Amateur Spannerman and the case of the sloppy forks.

Discussion in 'Technical and Troubleshooting Torque' at netrider.net.au started by Loz, Aug 26, 2006.

  1. Just finished servicing and slightly upgrading the forks on the 900, thought I'd pop something up about what I did and the effect it seems to have had.

    The Problem
    The bike is now over 50,000k old and the suspension has been pretty sloppy of late. Dive under brakes has been unacceptable, speed bumps have pitched the bike back and forth way too much, back end is bottoming out a bit under heavy cornering, wallowing a touch... It's been slowing me down in the twisties and robbing me of riding confidence.

    The Hornet 900 has what you'd call "budget" suspension - non-adjustable forks and a rear shock adjustable for preload only. It's set up to handle riders of about 60-80kg, not a fat mongrel like myself weighing in at nearly 120. And while it's coped for a while under this overloading, the suspension is well known to deteriorate with age.

    The fix
    Heavier weight fork oil to increase compression and rebound damping, and a set of new springs rated for the combined weight of the bike + lardarse here.

    Yanked off the front end, got the forks out, tipped out the FILTHY old fork oil which Glitch changed for me about 12 months ago... Wow, gross! That stuff fouled up real good real quick. Pulled out the springs, left the forks to drain.

    Took the springs down to Promecha, bought new heavier springs for $190. They're shorter, so I picked up some extra collar tubing and a stack of washers too.

    Plonked the new 15W fork oil in, measured it up for the right levels etc. Put in the springs, collars and washers, put the fork caps back on.



    In order to set the 20mm preload on the springs like the Promecha dude suggested, I pulled the fork tubes up to the end of their travel and measured the distance between that and the top of the fork caps. At this point you can add or remove washers or collar spacers to change the preload on the fork springs if your bike is like mine and has no adjustment available.

    Then it's compress the spring, screw the fork cap back on, do the same with the other fork and stick your front end back on, making elaborate and often unnecessary use oof a torque wrench if you happen to just have bought one. :grin:

    The Effects
    Wow. I'm not much good at understanding what's happening with suspension. I know when it's good, and I know when it's bad. Fiddling with this stuff and riding the Hornet afterwards has been very educational.

    The geometry of the bike is now noticeably different. The front end no longer sags nearly as much when I sit on the bike, so it sits higher. The poor old rooted rear shock still sits pretty low.

    This has also changed the steering geometry, making the bike less quick to turn but adding a feeling of stability in faster corners. I'm missing some of that chuckability at slower speeds, I might reduce the preload to address this if and when I can be buggered jacking the mongrel up and opening up the forks again. Shouldn't be so hard now I don't have to change oil - I shouldn't have to take the front wheel off, I might even be able to do it simply by sliding the forks through the triple clamps a bit to get access.

    The fresh, firmer spring feels fantastic over bumps and speed humps etc. It's no harsher a ride than the old spring (perhaps due to increased damping from the heavier oil) and it feels much more solid and dependable everywhere, especially in corners. It doesn't dive as much under brakes - although there's still more dive than I'd like after feeling what the '06 Blade is like on the stoppers.

    Promecha reckon a $400 revalve and set-up can turn shit into gold and that the spring-and-oil job I've done here is missing out on more than 50% of the benefits. If I had the cash, I'd get them to do it. The difference in feel is fantastic, it's really rejuvenated the front-end handling and I'd love to feel it revalved and set up for anti-dive.

    Looking Forward...
    I don't know if there's a quick and cheap way to similarly breathe life into my rear shock, which has been abused like a red-headed stepchild (for a while there I used to wheelie over speed humps, do a little back-wheel jump and try to keep the wheelie going when I landed. Real clever.) so I've nobody to blame by my own exuberant self there.

    Again, Promecha have quoted a little over $400 to re-funkify the rear shock, which, now that the more sorted front end is drawing attention to it, is going to play on my mind. It sounds a lot more complex than the fork stuff I was happy to play with myself.

    So there ya go, hope that was interesting, or helpful - the job was quite straightforward, it was a great learning experience for me (I finally understand what I was helping Glitch with last year), and I'd recommend it as a pretty cheap way to beef up a sad and sorry front end, either one that was originally undersprung or one that has deteriorated through age.[/img][/list]
     
     Top
  2. Grats on a success story, remeinds me of a full strip down of my old BMX bycicle and being like a totaly new bike to ride.

    I think for the front end, the forks should sag about 3/4 inch from full extension with you sitting on the bike.

    Non-rebuildable rear shocks are sometimes re-buildable, though I wouldn't know who to trust for this in Melbourne.

    It's an interesting ride with no shockys huh? I've ridden the same model bike with/without gold valves for the front-end and left impressed. Have them installed now in my Voyager forks but yet to finish rebuild. I'd love to have time/money at the same time : )

    Good luck with your rear.
     
     Top
  3. There's a guy in Walacia (syd) who will rebuild a rear shock for around $110-130 and trick it up for around $300-350.

    I forget his name but he's meant ot be pretty good.

    alternativly you could get a cheap aftermarket like a Hagon.
     
     Top
  4. Re: Rank Amateur Spannerman and the case of the sloppy forks

    Great read Loz. Always good for laugh. :LOL:

    I just used my new fancy new Torque Wrench for the first time last night. They are fantastic fun to use. It has brought a little science into my usual ham-fisted spannering.

    I used to use the Chairman's patented tightening system:

    Finger tight for delicate screws such as axle bolts and brake caliper bolts.
    Wrist tight for everything else.
    Break Wind tight for robust fairing and carby screws.

    IN TORQUE WRENCH WE TRUST!!
     
     Top
  5. LOL @ "break wind tight" :LOL:

    Yeah the torque wrench is a bit of a security blanket now, and an eye opener. It's been like "Oh, THAT'S how hard I should have been tightening my axle bolt... Shit. Ah well, the rear wheel's still there."

    For the rear shock, I'll probably go to promecha and get a revalve and service (they can do non-rebuildables) plus a "fat bastard" spring.

    I'm also looking at pulling the forks up through the triple clamps by 10 or 15mm to get the ol' girl turning in a bit quicker. At the moment the front end feels so high that it's almost like being on a chopper. Wieeeerd. Might remove some preload too if I can be buggered.
     
     Top
  6. good work buddy. have you had a chance to test if it's improved endoability?
     
     Top
  7. Very cool story - thanks for sharing the experience, and so entertainingly too.

    Having similar issues, though more at the back, on the Spada - i.e. bigger rider than the thing was designed/is set up for. I'll try getting the preload (which I believe is adjustable) cranked up a bit next time I get it serviced (I don't have the special tool), but could be looking at something a bit more drastic... it's just a bit wallowy, nothing really frightening, but ya know, I'm a big fan of a taut rear end...
     
     Top
  8. You know and I know I can't stoppie for shit dude! Best I've ever managed on the 900 has been maybe a foot or two off the ground, right before stopping - ie, pooftah beginner stoppies - and more often I get a front tyre slide.

    The geometry of the bike is now pretty unfriendly to stoppies as well - the front's too high. When I pull the forks up through the triple clamps it should put endos back on the menu. I can tell you it certainly stops better and more controllably, and feels more planted when hard on the brakes - so we'll see how it goes!
     
     Top
  9. Yeah, crank the preload up and then just live with it mate til you can get a decent sized bike. Most 250cc bikes have such thin and flimsy chassis parts that they simply can't take the weight of a big bloke who expects sporty handling out of them. Take a look at your swingarm next to a bigger bike, they're wafer thin and built for jockeys.

    You could respring and revalve it but unless you're planning on keeping the Spada long-term, you'll be throwing money at a sinking ship I reckon!
     
     Top
  10. Good call: that coupla hundred bucks can form the foundation of my SV650 fund. ;)
     
     Top
  11. hehe i'm the king of popcorn stoppies too. but yeah, i have slipped my forks up 5mm in the triples and it does help. there's more weight over the front and i've reduced the incidence of locking up dramatically. i'm working on them but the GooF2 forks are even more budget than the hornet forks. i need a 929.
     
     Top
  12. If that's your only issue with the bike, then go see www.promecha.com.au and get your forks resprung and revalved with their Provalve damping control kit. Around $600 with new springs, $400 without.
     
     Top
  13. Yo NAM - I dropped the height of the front and yeah, it certainly helps popping stoppies up :grin:

    Only had a quick punt at it but the front tyre seems to grip nicer as it digs in, I got no slide from it and the bike felt lighter at the legs to lift it.

    Perhaps I'll get back onto learning how to do proper ones.

    /Oh, and dropping the forks fixed the geometry up too, sharpened the steering back up nicely. I went about 20mm, I might still even look at removing some preload or going further down.
     
     Top