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Help Weird knocking sound from below front end of tank @ low speed - Suzuki VLC Intruder

Discussion in 'Suzuki 250cc Twins' started by Federal Agent at Large, Oct 27, 2017.

  1. Federal Agent at Large

    Federal Agent at Large Member

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    Hi,
    Lately Ive noticed a weird knocking sound coming from just below the front end of the tank on my 1999 VLC Intruder (250cc)
    I'm buggered working out where this knocking sound comes from - Dont seem to come from the steering head or the engine itself - sounds more as if something loose that bounces around at low spped
    Knocks seem to come and go at low speed (and appears to resonate just down the front end of the tank (but above the top cylinders) - so trying to work out where/what this weird noise is?
     
  2. my67xr

    my67xr Well-Known Member Premium Member Contributing Member

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    Could your air filter be sitting loose in the pod or airbox ?
     
  3. Murdo

    Murdo The Good Doctor Staff Member Premium Member Ride and Events Crew Contributing Member

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    Have you got the tank off yet? Could be the tank itself if the rubbers are worn.
     
  4. GreyImport

    GreyImport Administrator Staff Member The Big Cheese Contributing Member

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    Get the tank off and check that everything is tight ... all the nuts and bolts u can see ....like the exhaust manifold bolts
     
  5. Federal Agent at Large

    Federal Agent at Large Member

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    No, havent taken the tank off completely (still working on that one) - took it off earlier to the point where I loosened the back bolts and could see how the grommets held in place at the front (speedo housing off as well) - Couldnt see anything causing this noise - (but clearly would have liked to remove the tank completely to take a good look) - These grommets is a bit dry and the tank have a bit of side wiggle movement if you push hard'ish - but otherwise it seem to sit "sort of" firm
    - So, no I dont think its the grommets causing this noise - Its something else - someone suggested it might be something with the manifold (which I doubt since the bike most likely would have taken in air and run like a dog) - someone else pointed to the air filters (that one sort of makes sense even though theres nothing inside other than the filter and its filter frame) - this noise is more of a clonking sound - not some light weight plastic
    So, yes Im still scratching my head on what this really could be
    Doubled checked the steering head and its solid - so its definately not coming from there
     
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  6. Federal Agent at Large

    Federal Agent at Large Member

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    I have finally more or less locked this knocking sound to the timing chain
    But I have no idea if this chain can be tensioned or not - the 125cc manual I fall back on in lack of a proper one, show this timing chain being fed up the rear cylinder and cylinder head - If the chain need replacement that seem to suggest taking the heads off (and possible the rear cylinder) - a really dumb design
    The tensioner is also shown, but nothing stated if it actually can be tensioned or not (or when the chain needs to be replaced)
    Not sure I have the tools to take on this job - seem to be a big job, so wonder if anyone have an idea what a chain replacement would set me back if I brought it into a work shop?
     
  7. my67xr

    my67xr Well-Known Member Premium Member Contributing Member

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    Look's like there are a cam chain, guide and tensioner per cylinder like most v twin engine's.
    The set up of the VL125/VL250 look's like the 2x tensioner's are spring loaded like many other bike's are as well.

    To check the timing chain for wear
    When you do this, do not turn the bike over otherwise the timing chain/s may jump a tooth or more and make it hard to put back together.
    Once the tensioner's have been refitted then it'll be ok to start again

    Undo the centre bolt on one tensioner, remove the bolt, o'ring and the spring.
    Then undo the 2x outer bolt's which hold the tensioner body to the cylinder and remove the tensioner off the cylinder

    On the tensioner there is a spring loaded tab that stop's the tensioner from loosing tension, slowly try to pull the centre part away from the tensioner and count how many click's it make's as it come's out
    If it won't come out any more, then i'd be guessing you cam chain has stretched beyond the service limit

    To refit the tensioner, first you need to lift the little tab that hold's the push rod out, with the tab lifted you can now push the rod back into the tensioner body, make sure it goes back all the way in so no teeth are showing.
    Now it can be bolted back onto the cylinder, do up the 2x outer bolt's
    Next the spring can go back in followed by the bolt with the o'ring on it, as you push the spring in with the bolt, you will hear it click as the spring put's the tension back on the timing chain


    Most mechanic's will charge somewhere between $80 - $100 per hour to do the job, at a guess i'd say it'll take around 2 hour's maybe 3 hour's to change both timing chain's
    Might pay to have them check the valve clearance's at the same time too
    You or the mechanic will need to supply 2x new timing chain's, might need new o'ring's and gasket's for the tensioner's too so that's an extra cost
    He may also find worn timing chain guide's which can be expensive to replace too.

    CE_47296_1.JPG
     
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  8. Federal Agent at Large

    Federal Agent at Large Member

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    Thanks for this info - the service book (pdf as mentioned) touch on this timing chain, but 1. it looks like one chain, not two
    Secondly, its not clear how to tension this chain - pictures showing this chain all have the head and cylinder taken off - is this required to maintain (tension) the chain? Its a baboon ass ****** up design for sure (me being comfortable with shovelheads, this is miles apart with so much junk in between)
     
  9. my67xr

    my67xr Well-Known Member Premium Member Contributing Member

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    As far as i know you can't run a v twin with 1 timing chain, but i guess you could if it were long enough ?
    Is there a tensioner on each cylinder ?

    This VL250 engine picture is taken off the net,
    it show's a tensioner on the left (rear) cylinder near the engine case, and another tensioner on the other side of the engine (front) that can bee seen under the intake manifold here

    maxresdefault.jpg



    That part's diagram above in my other post is from the Suzuki part's manual, it's a part's diagram for the VL125/VL250 cam chain
    The tensioner's are self tensioning.
    I explained how the tensioner work's, and how to check if the chain is stretched beyond it's service limit's

    I guess you could alway's pull the Suzuki engine out and toss it,
    then Retrofit an Indian made water cooled baby Harley 500cc engine into it, but they are a single overhead cam V twin as well not push rod
     
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  10. Federal Agent at Large

    Federal Agent at Large Member

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    Thanks.
    Your right in that theres two tensioners - this is the only thing mentioned about this in the "service book" I got...
    Nothing mentioned about how to tension the chains, and with suggestions that the heads needs to be removed (following sequence of events in the book)

    The instructions you provided earlier, do these suggest that the heads is removed as part of checking the tensioners or ...?
    ... and just how would I know that the chain has proper tension against it?
    Sorry if Im a bit thick on this - never worked on designs like this before and its a bit of a challenge getting my head around it. timing chain tensioner.jpg

    Another little mystery you might help be sort is this hose on the right side that dont seem to belong anywhere...
    Noticed this hose while maintaining the air filters. Left hand side have this little sensor that hoses is connected to. No such sensor on the right hand side. Just coming down from top of center air cleaner box, then clamp holding it in place on the carb, fed into nothing.
    When I start the engine and put my finger on this hose (blocking it), the engine goes up in idle.
    Not sure if this hose is meant to be connected to something or if its ok as is?
    IMG_8656-2.jpg IMG_8651.JPG
     
  11. Andych

    Andych Well-Known Member Premium Member Contributing Member

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    As @my67xr advised earlier... you dont need to remove the heads to adjust the tension on the Cam chains but you might be better off getting a quote to do it at a Cycle Mechanic... it isnt a big job but if you dont know what you are doing you could crate the engine if you start it up and the tensioners are not done properly...
    Yep... that should definitely be connected up or plugged... I am surprised you have the bike running with that vacuum hose not connected up.
    Might be best to invest in a proper workshop manual...
     
  12. Federal Agent at Large

    Federal Agent at Large Member

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    Impossible to source one :( - best I managed to source is one covering the 2000 125cc vlc
     
  13. my67xr

    my67xr Well-Known Member Premium Member Contributing Member

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    That second picture showing the tensioner's has both tensioner's in it, labelled 1 and 2

    timing chain tensioner.jpg

    There is no need to remove the head to check the tensioner's, those instruction's are for removing the camshaft's and cam sprocket's

    The tensioners automatically adjust the tension on the timing chain via the internal spring, there may be a length measurement listed saying standard length and the maximum worn length somewhere in the service manual for the tensioner spring?
    Then remove your's and measure the length and compare the 2 measurement's.

    But i'm guessing if your chain is stretched, that the tensioner will be fully extended when you remove it, this mean's the chain is stretched.
    If you just take the centre bolt/o'ring out, and then the spring, you could put a small screwdriver in the tensioner housing and push on the tensioner rod to see if it click's out a tooth as you push it, if this is the case then the spring may have lost some tension and now be shorter so you may get away with replacing the spring with a new one if they're available

    You could also try converting the auto tensioner's to manual tensioner's, they generally have a little more adjustment available.
    You adjust the bolt thread so it turn's in until it touches the tslide and put's some pressure on the timing chain then do up the nut and lock it in place with the lock nut

    These are listed for the DR suzuki's (same tensioner is listed for the VL250 and DR Suzuki's here)
    "Replacement timing chain tensioner, suitable for Suzuki Burgman AN400 Maxi Scooter, Suzuki DR350 and more models"
    https://www.ebay.com/itm/Timing-Cam-Chain-Manual-Tensioners-For-Suzuki-Off-Road-DR120SE-DR200-SE-DR250S-E/122720469160?_trkparms=aid=555017&algo=PL.CASSINI&ao=1&asc=20150817211758&meid=86577cf0f75b4f948e8604b875eba836&pid=100507&rk=1&rkt=1&&_trksid=p2045573.c100507.m3226

    s-l1600.jpg


    That hose look's like it's a water drain hose (part number 11 ?) from the bottom of the air box, or is it another shown in the diagram ?
    If it's number 11, there may be a small one way valve that is missing from in the end of the hose ? or it may just be open.
    I don't think it goes anywhere as it would be shown with a spring clamp on it in the part's diagram
    If it's number 26 then i think it would go to a port on the carby somewhere, it come's from a solenoid Suzuki called Valve Comp Air

    CE_33653_1.JPG
     
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    Last edited: Jan 14, 2018
  14. Joker

    Joker CLUB250 Premium Member Contributing Member

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    I am not sure what type of tensioner you have, whether automatic or manual. By the looks of it, if there is a large bolt in the rear of the tensioner it is probably an automatic one similar to the FZR items I have. Here is a picture of one of mine of my FZR400.

    Essentially you can check tension by undoing the rear bolt and pulling out the springs. I don't think the orientation you pull the springs out is that important, or put them back in for that matter. Some tensioners may have a smaller spring inside a larger spring which all of mine do.

    Then you can undo the side bolts and simply pull the tensioner off. Make sure you do it in that order, if you pull the tensioner off first the springs will push it all the way out and you might find it difficult to pinpoint exactly where it was. You can see that mine has a small black gasket on the threaded side of the bolts. If you don't have replacement gaskets just get some 0.8mm oil jointing gasket paper and a hobby knife and make yourself a new one.

    Once you pull the tensioner out, DO NOT TURN OVER THE BIKE or move it, you don't want to risk the timing chain moving teeth on the camshaft sprokets. The inspection is pretty straightforward, on the left of the photo you can see some grooves and an imbedded clip with a spring against it. What you want to see is if the tensioner is pulled all the way out, or if it is somewhere midway like the one below. I can push on the spring side of the clip and pull the tensioner all the way out. You might mark where it was so you remember (just in case) before attempting to do the same but in theory the tensioner should work automatically once you put it back in and reinstall the springs.

    One thing I have done before with strange noises is leave the tensioner in place, remove the middle bolt and the springs, and get a small screwdriver. I push the handle of the small screw driver into the hole and push until I hear a single "click". This would add another notch of tension to the chain. I've done this sometimes because it almost felt like the tensioner (due to older springs etc) was sorta halfway between notches so pushing it out by one notch sorta puts it where it wants to be.

    I suppose a similar strategy could be tried with yours, I don't think a notch is going to hurt your engine or anything (happy to be corrected by others) and maybe the noise will go away.

    Failing that put a screwdriver on the ear lobe while the bike is running and listen to the top end. There are 3 noises:

    1. A ticking noise like a clock is a valve problem (potentially valve clearances)
    2. A scraping noise like a bicycle chain being pulled over a plastic cover is probably cam/timing chain
    3. A distinct knock, like a blunt knock on a wooden table is the biggest problem - big end/bottom end bearings.

    Perhaps try and pinpoint the noise to the top, middle or bottom section of the engine. It may not even be the engine, perhaps a bracket or clamp came loose and is simply flapping on and off in the wind - pulling the tank off and placing a piece of wood under it for visibility if you don't want to disconnect anything is one way of attempting an inspection.

    Good luck!

    15027697_10157712945300716_1058574902636540607_n.jpg
     
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  15. Federal Agent at Large

    Federal Agent at Large Member

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    Nop! Its not the water drain hose, nor is it the sensor hose (26) - This one sits on the other side (as per pic) - Some suggest that I should plug it, but not sure if this is a good idea - About a year ago I had it in for a carb tunup with a local Suzuki shop, and they didnt mention or do anything to this hose as far as I can see (but then again, it was just the other day I picked up on it)
     
  16. Federal Agent at Large

    Federal Agent at Large Member

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    Problem is that the knock only appears at very low speed - Nothing while being stationed, and nothing when you get up to speed above 20km/h
    - I did take the tank off to check - couldnt find anything loose or an explanation to this knock

    So Im sort off locking it down to the chain - but perhaps I should hear this more constant and frequent if it is the chain - not sure
    One thing for sure is that this knocking is getting worse and more persistent @ low speed (used to come and go at random, now it seem to happen all the time)

    If it should turn out to be the bottom end bearing, is it likely to behave as I just described or would you hear this all the time (even when the bike i stationed) ?

    Its a difficult one I guess :(
     
  17. my67xr

    my67xr Well-Known Member Premium Member Contributing Member

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    So if it's not number 11 or 26 which hose is it ?
    Cant really tell anything from your pic, no port's open on the carb?
    suzuki-vl-250-intruder-carburetor-assy-carburetor-13200-27f50-000.jpg

    It's not off a vacuum port for the fuel tap ?
    Or a drain or vent hose off the bottom of the fuel bowl?

    Second air parts
    SU4_-2106675.png

    Does it sound anything like this ?

     
    Last edited: Jan 14, 2018
  18. my67xr

    my67xr Well-Known Member Premium Member Contributing Member

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    Hose to intake manifold port ?

    suzuki-motorcycle-vl250-vl250-k2-motor-transmision-1a-cylinder-head-front_1000.png
     
  19. Federal Agent at Large

    Federal Agent at Large Member

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    No - just a deep clonking sound that comes a goes - nothing like on this video (that sounds like lifters/taps being poorly adjusted though)

    ... and the sound only appears at very low speed - never heard it at higher speeds (above 20km/h) or when its still (with/without gear with/without clutch engaged)
     
  20. Federal Agent at Large

    Federal Agent at Large Member

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    This hose does not go to/from the carb - its fed up in between the tank (and from what I can work out its attached to the big air filter center box)
    The hose is also short enough to sit where its sitting - bending it towards the carb would squash the hose - so I dont think it ever went there.
     

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