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Suspension feels a bit "underdamped"

Discussion in 'New Riders and Riding Tips' started by magin, Apr 12, 2012.

  1. So the title says it all, my suspension of the VTR250 feels a bit underdamped to me (inexperienced me). If I hit a bump on the road, I can feel the bike bounce like maybe twice through the "equilibrium position" of the rear suspension. Is this normal? If not, should I bother do anything about it? I mean, the bike is very ride-able and I'm not thinking it has any problems, but I have noticed a bit of a trampoline feeling at times (especially when leaning into corners), and the other day on a ride, I think the back may have bounced of the road a bit and spun a little. I have a car with the same issue, (or maybe I'm becoming paranoid) but I'm fairly confident I use both vehicles according to this characteristic and it's not a safety concern.

  2. Sounds like it is for your weight/size. Suspension components can get expensive, so unless you plan to keep it, you'll be waiting money. You could try a replacement rear shocker from a wreckers. Yours might be stuffed, whereas theirs may have some life left in it.
    A stiffer spring may help, but again, that requires a pro, who will likely recommend a shock overall, to match a new spring.
    But if it is jeopardising your safety, you might have to get it done. Front forks will also require some mods to match the rear.
  3. Thanks for the advice! I really like the bike, but i doubt I'll be keeping it, unless I have the money when I'm off my LAMS restrictions to keep both the VTR250 for commuting and buy something more suited for touring, or maybe a sports bike. I don't think it's a safety concern really either as being a newbie, I'm not taking corners as fast as possible, leaning right over to the limit of the tyre. I think I have a pretty good error margin when I ride or drive so not perfect suspension probably isn't that bad.
  4. Sounds like the rear has lost some of its damping. It's a common problem at the cheaper end of the bike market. Time was when you could get a cheapo pair of universal shocks which would see you through the next year or so, but modern monoshock setups are a bit harder to fix cheaply.

    Way back, pretty much any older bike would have zero rear damping and would provide endless excitement by bouncing wildly towards the outsides of bends if the surface was less than perfect. Learning to cope with this tendency was all part of learning to ride briskly.

    As Raven points out, shelling out several hundred dollars for a shock is a waste of money on a 250 unless it's bad enough to be actively dangerous. If you approach the bikes (and your own) limits gradually and sensibly it would have to be very bad indeed before that were the case. IMHO of course.
  5. Absolutely it does not require a pro to install a new spring on a motorcycle shock. All that it necessitates is the removal of the shock, the backing off of the preload adjuster and removal of the spring, installation of the new spring, reinstalling the shock and getting a mate to help you set the sag once you have also installed front fork springs to match the rear. Of course the damping will also need to be adjusted. It is no more complicated than say, replacing the carburettor. However this is from a DR650 point of view, a VTR250 may be more complicated to do this work but given that it's a budget 250 Honda learner bike... it wouldn't surprise me if it was easier than the DR650. Revalving a rear shock, however, is a job best left to the pros; but I'd say for a learner's skill level all that is required is to install springs suited to the rider's weight.

    Magin, if you are confident with the tools there is no reason why you can't do this work yourself. All you will need is the service manual, something to lift both wheels of the bike off the ground or at least one at a time, the appropriate tools and a mate to help you set the sag. Contact any motorcycle suspension shop, tell them what bike you ride and describe to them your approximate weight when geared up and your riding style, and they will be able to order you springs to suit you and the bike. Where do you live? If you're not confident working on your motorcycle yourself, getting a suspension shop or even a backyard mechanic like Mark Rees (which many people highly recommend) if you live in Melbourne to install your springs shouldn't be very expensive, Mark Rees is likely your best option if you are on a budget. You can find him on the Motorcycle Riders Melbourne facebook group.
    If you think you can tackle this without the aid of a professional mechanic, once you've installed the heavier springs, here's what you need to do to set your sag:
    First you need to measure your motorcycle's total suspension travel, that is how much the springs will compress/the bike will lower from the suspension being fully extended (both wheels off the ground) to the suspension bottoming out (the rear shock is riding on its bottoming damper). Use a plank of wood and a texta to mark a point where the bike's suspension is fully extended, the end of your handle bars is a good reference point. Then use ratchet tie downs to fully compress the motorcycle's suspension. Using the same reference point, mark your plank of wood with the texta again, and measure the distance between the two marks on your plank of wood (all the time making sure your plank of wood is straight!!). This is your motorcycle's total suspension travel. Come to think of it, you'll probably be able to find the exact specification for your bike's suspension travel in your service manual, but if you can't, then I think the method I've outlined should work.

    Second, you need to set your sag with your springs installed.
    This information is taken from a post by Procycle, a DR650 specialist shop in Oregon.

    Sag is measured with rider weight. A stock DR will sag about 50% on the factory settings.

    Here's a tip for measuring sag:
    It takes 2 people. You - sitting nearly balanced on the bike.
    A helper pulls the suspension down and lets it slowly rise up. Measure this point.
    Helper lifts the bike on the suspension and lets it slowly settle down. Measure this point.

    The sag measurement will be midway between these 2 points.

    You need to make preload spacers for the front forks, PVC pipe of the appropriate diameter is perfect material, and adjust the preload adjuster on the rear shock so that the sag measurement is about 1/3 of your total suspension travel. The rear shock is a simple matter of experimenting, it's easy to adjust the preload adjuster, however I'm not too sure how you figure out how long your preload spacers for the front forks should be, hopefully someone can chime in with that information, otherwise I'll do a google.
    This all might sound quite complicated to do but once you are doing it, it is easier than it sounds. You should be able to knock the job over in a day or in a weekend at max, as long as you don't encounter any major road blocks.

    edit: Oh yeah, if the rear shock internals are towards the end of their life... time to get them rebuilt. If you're only keeping the bike to learn on, most likely cheaper to get a shock from the wreckers that has more life left in it than this one, and then if the suspension still feels overwhelmed, install heavier springs. You should be able to get away with doing it for less than $800 and it will make a major improvement to how the bike rides. You will find yourself going into a corner, and suddenly thinking: "Hang on a minute, this is quite a bit faster than what I was able to do just yesterday!"
  6. Kernel, physically putting a spring on wouldn't necessarily require a Pro, no.
    The pro is for everything else that must go with it.
  7. Any obvious signs of oil leaking from the shock?
    There is an old thread with a similar problem at https://netrider.net.au/forums/showthread.php?t=83641&page=2 where a member, Trevor G, had his rebuilt for $80 with an original quote of $180 - back in 2007. He refers to a link in another thread mentioning a Brisbane company who did the job - rebuild the same shock.
    I can't locate the thread he refers to but the mob might be http://www.radmotorcycleshockyrepairs.com.au/ I know someone from Sydney who just sent 2 shocks to them and was happy with the work for $80. Admittedly, they were shocks that were supposed to be servicable. I reckon nothing is lost tgetting in touch with them.

    These guys in Brisbane are "Specialising in sealed or non-serviceable units"