Ss Front Cylinder Noise.. Increases When On Stand

Discussion in 'Supersport (1974-2007)' started by chueewowee, Apr 7, 2017.

  1. May I ask, while we're here, is it usual practice to replace both nuts and studs on a head rebuild, or just nuts on the supersport?
     
  2. The earlier studs were prone to failure and updated as a result, I don't remember what visual clues to give you, they were replaced when they failed or recommended by conscientious mechanics if the heads were off anyway.
    There is no reason to change the studs if they are OK, particularly if you find out they are the later type or aftermarket like Nichols.
     
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  3. Brilliant, thanks for that.
     
  4. Theres a stamp on the end of the rod, think you want the 'O'. The colours also different, silvers bad and black is good, most bikes have had the early ones replaced by know as its a well known problem.
     
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  5. You're a gent DesmoQ.
     
  6. Sounds like my xt500 race engine when the rocker arms started to wear,are the rocker arm and cam profiles in good order?
     
  7. Cheers for that RCV4. I can't tell you, because though I've examined the exhaust rockers, and the cam and see no obvious play on either shaft, It was a limited view there in situ with a torch; I've not removed the cam and rockers, which is something I want to do first; yep, a rocker may be moving on a worn shaft, or something like that... especially considering there was no gap on one exhaust closer.
    Yep, that's the thing to do next - cam, exhaust and inlet rockers.
     
  8. Check the shimming on the rocker shafts between the rockers and clips at the cylinder head walls.

    I have seen heads where there are combinations of shims between the walls and the clips as well as between the walls and the rockers, plus shims between the rockers and the clips; but I have also seen where there is only one or no shims at all.

    I guess a worn wiping face of a rocker with bad or no shimming could cause a rocker to jump sideways and knock against the head wall, but it would have to be quite a big gap to cause a loud noise.

    AL
     
    #48 Arquebus, Apr 19, 2017
    Last edited: Apr 19, 2017
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  9. Cheers, Al. What you've described is what I wanted to determine.... the shims and clips on intake and exhaust are in the right place (one each side of the clip) but, As I got my head around this set up, I had to wonder at it.... being used to accurate shimming and gaps on a rocker shaft.
    Given that one clip was badly deformed sideways, it is possible that this caused wear on a shim. Is there a procedure for shimming up (exact tolerances) here - I've not seen that info in Haynes?

    I want to get this particularly, right before I proceed further.

    I didn't realise a rocker could knock against the head wall, not with a clip in place... I'll take a look.
     
  10. Update - found something tangible:

    Confirmed distinct sideways play on horizontal exhaust opener rocker and shaft after (moved toward rider left with a sound reminiscent of the offending noise when idling, and exacerbated when leaning the bike that way); Around two mm movement. By comparison, such movement was absent in the inlet opener.
    I removed the exhaust opener rocker and see the chrome on its' cam arm is breaking up at edges (see pic below). Shaft is no more than 0.01 mm out if true - unable to determine the rocker bore but that's suspect, given the movement.

    Plan on running her with the new rocker to see difference, before pulling out to measure the cam profile - until then a visual inspection in situ found nothing alarming.
    Ordered a brand new rocker (from On yer Bike, Bucks £60 odd pounds): unable to find tolerance data on shims, but reckon I would need new or extra. Ideally I'd prefer to replace the rocker shaft at same time: I'm using a 2001 750sss parts catalogue - all I could find: should I be content with that in general, or do you know better (for 1997 600ss). I really need a parts catalogue to rely on....

    With my old bikes I would have checked stripped the cam and followers immediately, but have been hesitant and slow with the ducati.... because I'm pretty busy, and I felt I had to learn with caution in stripping it, and learn the routines/methods. Plus I found I needed to overhaul the carbs, then take her for more runs. At first I just cleaned the carbs out which helped, but they needed more, and so I could observe her running nicely in that way.
    I'm more confident now but, no doubt, subtleties to learn. I'm slowly investing in necessary tools. Hope to make some up when I get my garden workshop built - I'm laying down the base right now.





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    #50 chueewowee, Apr 20, 2017
    Last edited: Apr 20, 2017
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  11. I hope this will help a bit - note the different shim sizes and locations.
    HEAD1.jpg HEAD2.jpg
     
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  12. As regards the wee shim washers, when they are put in the rocker should be bang in the middle of the valve end. I dont think its an exact science there should be a couple of washers each side, its more a matter of getting it central with very little play. Those clips really do deform easy, I've done it myself removing them, but they bend back easy enough.
     
  13. OK Ta AL.
    The 2001 750 ss parts manual shows just two shims, one either side of the clip, my bike has three - one each side of the rocker and one between the clip and casing. With leads me to conclude they are fitted on a per-engine basis, to centre the rocker and give correct clearance, with one shim always each side of the clip.... So, I'll just take a clearance reading from another rocker and use that in some statisfactory way.
     
    #53 chueewowee, Apr 21, 2017
    Last edited: Apr 21, 2017
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  14. New exhaust opening rocker fitted improved things: side clearance closed down to 0.06mm (which compares with 0.03mm on a good inlet opener) - shall obtain shims to close it further, some wear on existing ones. The new inlet rocker closed down opening rocker shim clearance to 0.15 mm from 0.2mm with existing shim.
    Mechanical sound is improved, but still get what is tappet or valve clatter, much less rackety though - more like one clear sound, and doesn't get worse on leaning.
    Perhaps new rockers need running in until noise dies?
    Or, more likely, I still have closer rocker and the shafts to deal with, possibly a valve and seat. Next I'll make a spring holding tool if possible, and inspect that closer, then remove head.
    Meanwhile, I shan't bore you with more updates: pretty sure we nailed origin of noise as valve train.

    Thanks all for kind interest.
    John





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    #54 chueewowee, Apr 26, 2017
    Last edited: Apr 27, 2017
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  15. On further inspection with horizontal Head and barell removed:
    Piston sloppy on Gudgeon pin.
    Conrod to pin clearance good. Piston to pin suspect.
    Gudgeon pin slightly oval - approaches 0.05mm out of true; but wonder about piston - is it meant to be oval with a cutaway for oil (doubt it) because it's 0.8mm out in one direction at the grey colour section, on both bosses. See picture...

    [​IMG]

    Scuffing on piston skirt, measures 80 mm at that point.
    Barell is at about 80mm (measurements +/- 0.05mm)


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    #55 chueewowee, May 9, 2017
    Last edited: May 9, 2017
  16. In short, no.
     
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  17. Cheers. Well this piston is in very bad shape. I wonder how it began on (only) this cylinder. Never seen anything like it.
    Have to find a replacement
    Pretty sure this is the cause of the unacceptable noise.
     
    #57 chueewowee, May 9, 2017
    Last edited: May 10, 2017
  18. So it looks like it was piston slap as some suggested - such a strange, metallic noise...

    As you say, why - poor lubrication???

    Fuel getting past the rings??
     
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  19. Hadn't once heard in my searching that the well reported problem of Ducati SS 'piston slap' was ever due, as in this example, to unusual wearing in the piston boss. I only heard repeatedly it was the downward facing piston skirt that was slapping the bore.
    Oval wear (0.8mm in places) in the piston boss occurs as centred at about 10 and 2 'o clock; not in directly opposite places. A symptom of thrust at rotation of crank at top and bottom DC perhaps, in this horizontal layout? :frowning:
    Supposedly ( I read) a post '98 piston change from forged to cast solved the problem of 'piston slap', in 600cc motors. So now I ask myself, what did it solve if not premature wear in the boss? I don't suppose cast is better than forged either - so perhaps it a change in material that worked.

    Regarding fuel and rings, I've yet to measure the piston rings. Regarding lubrication as a cause, there are no other signs of mal-lubrication generally, nor on the other cylinder as regards piston-pin clearance and noise.

    Q. Would monster 600cc pistons, pre and post-98 fit the 600ss? I imagine so, or did they begin to use larger valves/cutouts at some point?


    BTW. both opening rockers were flaking, but the closers, not at all.
     
    #59 chueewowee, May 9, 2017
    Last edited: May 10, 2017
  20. This isn't what I understand as 'piston slap' which I always understood as meaning a slapping skirt. I think the noise is from a piston rattling on the pin, perhaps most likely on downward stroke. I stated a while back my suspicion that the noise was gudgeon pin. I doubted from the beginning it was a slapping skirt. Piston to bore clearance is fine, scuffing on skirt, but little wear.

    So, has in fact, the common problem of 'slapping piston' always been wear in the boss, I wonder?
     
    #60 chueewowee, May 10, 2017
    Last edited: May 10, 2017