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Engine noise at Idle

Discussion in 'XJ Technical Chat' started by a100man, Oct 31, 2015.

  1. a100man

    a100man Well-Known Member

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    Hi all

    Although I've been messing about with my 550 self-assembly kit for over a year I didn't pull it out of the shed and try and get it moving until tonight as I only just got the chain and sprockets on. So it starts ok albeit a bit loud through the alfa pipe. But the clutch was stuck (not surprisingly) and so I had to rev it up to about 2 k before clicking it into gear to unstick it. A quick trip up the road to run it through a few gears and it pulls strong all in all seems not too bad considering EXCEPT that at low idle it sounds like a tractor ! A really pronounced rattle that sounds like its coming from teh bottom end rev it to about 1500 and it seems to smooth out however. Carbs were bench synced but no more than that, plus I'm running BS 28 550 carbs on a radian engine that should have BS30s..Any thoughts ?

    PS I made a 'video' of the noise - not sure though if I can post this here 20151031_171310.jpg
     
    a100man, Oct 31, 2015
    #1
  2. a100man

    a100man Well-Known Member

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    a100man, Oct 31, 2015
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  3. quebecois59

    quebecois59 Well-Known Member

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    Normal idle speed should be around 1050-1100 rpm, yours sounds a lot lower than that. You could increase the idle speed with the knob behind the carbs, between #2 and #3 carbs. You should perform a running sync if you want your engine to idle smoothly.
     
    quebecois59, Oct 31, 2015
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  4. a100man

    a100man Well-Known Member

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    Yes indeed. I have adjustedthe idle since the vid and there's an improvement, now I need to to try an balance it all. I have no rev counter at present (I have fitted an electronic for the 600 but not wired it all in to the coil) so it's a bit of guess work..

    Thanks for the reply, and not condemning the motor straightaway by the way !
     
    a100man, Oct 31, 2015
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  5. XJ550H

    XJ550H Well-Known Member Premium Member

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    yep the 550 is noisy at low rpm and speced rpm. think i read its the primary chain possibly the cam chain did you adjust your cam chain tensioner ?
    I found a few more ounces of oil make that sound go away just make sure you still have a bubble in the sight glass.

    if you have Seafoam available to you you can put 1 or 2 ounces in the oil to clean up the clutch sludge
     
    XJ550H, Oct 31, 2015
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  6. a100man

    a100man Well-Known Member

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    Yes oil is a bit on the low side, about half way in the window. This engine is unknown to me too be honest. but I will persevere with this encouragement..
     
    a100man, Oct 31, 2015
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  7. k-moe

    k-moe Pie, Bacon, Bourbon. Moderator Premium Member

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    That rattle is down to the primary chain tensioner being slack. It's a hydraulic unit. Fitz set both of his 550's idles a bit higher than the factory to eliminate the rattle. Even the shafties will make that rattle if the idle speed is set too low.
     
    k-moe, Oct 31, 2015
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  8. a100man

    a100man Well-Known Member

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    OK so raise the oil level, balance the carbs and increase idle speed (done) will all help I guess..

    Cheers

    J
     
    a100man, Nov 1, 2015
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