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.

Chain tension when the manual seems wrong

Discussion in 'Technical and Troubleshooting Torque' started by mattb, Nov 30, 2011.

  1. G'day All.

    I find that following the factory workshop manual to a 't' for tensioning the new chain on my new W650 - with the bike on the centre stand the slack should be 25-35mm (and I've given it around 30-35mm) - that the chain appears too tight to me when sitting on the bike. There's a little movement, maybe 5-10mm, but having stripped a drive shaft in the past on another bike this makes me nervous. When I got the bike from PStevens a few weeks ago it matched the amount of play just mentioned in both cases. But I'm uneasy and I'd rather risk higher chain wear than damage to the drive shaft. Maybe the manual hasn't taken into account 100kg Westerners like myself.

    So, What would be your suggested chain play for the bike when I'm sitting on it?

  2. I have the same issue with the factory manual figure and technique for the DR. Correct according to the book is bar-taut when I'm sitting on the bike and will only get worse when the suspension compresses over bumps.

    So I set it slack and then paddle the bike around, giving the chain a prod at intervals to see if it has what I judge to be enough movement at all points as it goes around.

    What constitutes "enough" is a bit of a judgement call. I look for maybe 15mm of up-down movement without feeling like I'm physically stretching the thing. I've never actually measured it, just gone for what feels right. Obviously I also ensure that the slack is not so much that the chain will hit anything other than the sacrificial guides/rollers (pseudo dirt bike with longish travel suspendies makes some contact inevitable on full rebound) which Suzuki so thoughtfully provide.

    It seems to work 'cos, in combination with a Scottoiler set on the generous side of Eeuuurrrrrggh-Where's-All-This-Bloody-Oil-Coming-From, at 41,500 kms my snail cams have a good 90 degrees to go before I run out of movement on the OEM chain and I have yet to flog out the gearbox output bearing.

    I would strongly recommend not poking the chain at any point where your finger may end up twixt chain and sprocket
    • Like Like x 1
  3. Always adjust while bikes on ground and sitting on it. With me on and its firm but not tight, I back it off and I give it an inch and half slack from top to bottom guitar string plucking in freeplay. Mind you thats on a Bandit 12 and GSX 14. Both have fair bit of torque and stretch shit out of chains if not enough free play.
  4. A DR will need more slack than the W. I think. The more suspension travel the more slack needed.
    Does it really say to do it on the stand. I've always had it set by manufacture figures by way of the bike upright with static sag only. That should be enough through the suspension travel range
    Does the slack measurement on the chain guard match the manual?
    I know we all neglect them but too tight and you are up for a bit of time changing counter-shaft sprocket seals and cash replacing your drive gear early.
    On most ROAD bikes the chain slack with the bike standing alone on it's wheels.."static sag".. is around 25 to 35mm.
  5. Thanks guys. With me on it I have given it about the same freeplay weighted as the manual suggests for un-weighted. This greater slack doesn't appear extreme at all to me and the bike rides more smoothly than with the more tense chain. If it happens that I wear through chains and sprockets more often, it won't be too extreme I'm sure and the $150-200 that a set costs for a bike like this makes it negligible.
  6. Yep Bretto, up on the centrestand. I did play around with comparing measurements between on the centre and on the side stand and they weren't too different (I've got the suspension at its stiffest setting).
  7. Sounds like you on the right path. I wouldn't say it was too tight with 5-10mm with you on it.
    It wont die early loose. New chains will need a few inspections. You will hear it slapping on the swing arm guide if it's too loose anyway.
  8. Factory manual or Haynes or the like?

    My Haynes says do it on centrestand but when I finally got a pdf copy of the handbook it says with wheel on the ground. And as you say there can be a considerable difference.

    If factory manual I would ask Kawasaki direct.

    Until then I would be tempted to use the wheel on ground method.
  9. That's how I do it, first tip my old man told me when I got a bike with a chain, rather than a shaft :)
  10. I only know not much about sportsbikes, but I run mine a tad looser than the manual, and have it just loose enough for the chain to touch the rubber guide towards the swingarm pivot. The chain just makes a slight smiley face. Too loose and it gets snatchy on the throttle.
  11. How weird. I have never heard of it being measured on the stand.
    Funny, if I am checking one with a center stand I will have it down to the ground but not on it. Like I have the stand down till it touches the ground. Then I can stomp my big toe on it and that is enough to hold the bike up and steady on flat ground.
    This gives me both hands free.
    Just wondering if some guy did that while the scribes were writing it all down and they presumed it was on it. Nah ha ha.
    Wow. Might have to ring peter at Kawa tech and get his opinion on it. He will laugh at me :(
  12. In the old days,when long travel suspension first arrived on dirtbike this was critical.The chain is at its tightest when the counter-shaft centre the swing arm pivot centre and the rear wheel centre line up.
    This is usually with a load on the bike.To tight and you can rip the counter sharf bearing out of the case,seen this,not good.
    In those days the counter shaft was usually a distance away from the swing arm and this resulted in a huge amount between loose and tight,they compensated for this with spring loaded chain tensioner.
    These days the counter shaft is kept as close as possible to the swing arm pivot to negate this but unless there adjacent,like Spondon used to do there will always be some looseness and tightness with suspension travel.
  13. What Pat said. Better to err on the loose side than too tight.
  14. It's the official Kawasaki manual.

    It is worth checking out with Kawasaki directly. I might send them an email. But I wonder whether they'd be prepared to contradict their own manual, especially in writing. If people do damage to their bikes based on the official manual's suggestions then I imagine they could be liable.

    I chucked my original question up on the W650 Yahoo thingy last night, and got the advice that I should go with the manual. But that opinion appeared to be based on the assumption that the manual must, a priori, be correct. When I tightened the chain according to the advised free play yesterday, it definitely felt too tight to me.
  15. Yeah right , manafacturers don't make mistakes.

    Apparently official BMW manuals contain several errors converting Newton.metres to Foot.pounds in their official torque settings for various bits and pieces. oopsy

    If it is the official manual one hopes it should be correct but if it feels tight I would err on the safe side.

    Did it definitely say centre stand and not just stand (e.g. as in paddock stand)? A centre stand will leave the swing arm dangling while a paddock stand will load the swing arm and virtually mimic the wheel on the ground.

    Try contacting them and say why you are asking and see what answer you get.
  16. Yep, "Set the motorcycle up on its center stand for drive chain inspection." It then states "Drive Chain Slack Standard: 25 ∼ 35 mm". Then it proceeds from if the chain is loose, then tension it such and such a way and then recheck the free play and then tighten the axle bolts, without any hint at any point that the bike be taken off the centrestand.

    Where chain tensioning is mentioned in the rest of the manual, it simply refers the reader back to this original description.
  17. So what sort of tension does this give when the wheel is on the ground and you are on the bike?
  18. Very little. There is movement, and I might guesstimate 5-10mm, but it was a tight feeling 5-10.