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There is a knocking sound coming from the engine

Discussion in 'Technical and Troubleshooting Torque' started by Spud Gun, Feb 15, 2005.

  1. I am getting a consistant knocking noise coming from the engine. It is loudest at lower speed/revs. It does speed up when I go faster, but doesn't slow down when I change up a gear. Its more of a knocking than a tapping. I can't hear it at 80KPH+, but that could be duw to wond noise. Any ideas what it could be? I am leaving it in for a full service this weekend but I want to know a few things that I could say to the mechanics so that I don't sound like a muppet. From what I understand, it could be sparks, fuel or compression. The fact the rate of noise doesn't change when gears are changed, would that rule out compression? Any other ideas as to what it might be?

  2. If the frequency is speed dependent rather than rev dependent then the problem is most likely going to be running gear (gearbox (final drive rather than input drive), drive train, hub bearings, etc) Doesn't narrow it down too much other than to say that it isn't likely to be the engine itself and is probably going to be a bit cheaper.
  3. ??cam chain??
  4. Wouldn't a cam chain knocking change with revs rather than speed?
  5. The babyblade suffered the same thing.
    It ended up being the cam chain tensioner.

    Good luck with it.
  6. It could be your 'big end', as it were...
  7. I am leaving it where I bought it 2 months ago, Action Motorcycles. Its also a Suzuki dealer which will help for parts. At the time of purchase the did a pre-sales service. Which was a fluids and lubricant check. They did say that if there was anything that needed replacing, they would work something out with me. Vic, was the cam tensioner expensive to replace?
  8. Suki's do have issues with there tensioners, sometimes they come loose and they just need retightening but mostly replacing.
    Average cost of a tensioner is around $60 for a suzuki
  9. If it doesn't slow down changing gears then the top end, big end and cam systems are all ruled out. These all rotate directional proportional to engine speed, not road speed.
    I suspect the noise is not present when idling and stationary - which would confirm the diagnosis. Need to let the mechanics know if this is the case. If it is still present then indications point firmly to clutch / gearbox - depends on the bike.

    Could also be chain / sprocket related.

    Let us know when you get it diagnosed.
  10. Can you put the bike on a centre stand of bikestand.

    If you can do that and rotate the rear wheel. Feel for any resistance.

    It could be a siezed chain link or something on the rear tyre or the drive sprocket of counter shaft.
  11. to test if it is your chain or running gear
    while riding pull the clutch , if it is there still it could be chain or sprockets .
    by keeping your foot on the gear shift lever you should feel the vibration through your toes .

    if its cam chain tensioner rev the bike in nuetral and it will make a tinny rattle

    it sounds stupid , but check your stand to the springs lose there tension and they tap on the under side of the bike .

    electricals , dont normally make a knocking noise , ping maybe , but not knocking
  12. It seems to be most noticable when getting to 40KPH. I think at that stage it starts to get noisy so I cant hear it too well. It doesn't happen when idling, or when reving stationary (in neutral or clutch in). Also, its seems worse when cold (or maybe i get used to it after a while). I am leaving it in this Saturday morning. I'll let you know the verdict when I get it.
  13. If it doesn't happen while reving a stationary bike then you can count out the engine. That's why the knocks are related to road speed rather than engine revs. The chain and sprockets are a good place to look. Most likely something is loose or misaligned. problem is it could be just about anything. Try riding in circles around a mate and get them to locate the general area the noise is comming from eg. Back/front wheel, or engine mounts etc... Once you do that you'll have a much smaller search area in which to wiggle bits.
  14. Front sprocket needs replacing!
  15. Ok, I left it into Action Motorcycles in Sydney on Saturday morning. I was told that a full service would cost $750. I politely told them that I would on my arse pay that for a bike service, especially for a bike I bought there 2 months ago. I also pointed out that the 40K service on my car cost over $150 from a dealership. $750, daylight bloody robbery! Anyway, I got talking to the head of the service department and he said that he would take care of it and diagnose and fix the knocking. I collect the bike tomorrow, provided I can pay for the service.
  16. Just had the garage on the phone. A new front sprocket was required so 10/10 to Bond Girl for getting it right. I also need a new clutch cable which is a bit of a bugger, not good news. Also at some stage in the near future, I will need a new spline. Can anyone tell me what that is?
  17. a spline or a spleen ?

    1 is on the bike, the other is in you !
  18. I have no idea where either is! How much is a new spline for a bike?
  19. A Spline is a rod with groves.
  20. Spud,

    They are probably talking about the splined shaft onto which the front sprocket mounts.

    This doesn't sound cheap. Maybe source one from a wreckers