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Tight valve locknut...

Discussion in 'Bling and Appearance' at netrider.net.au started by mattb, Aug 1, 2007.

  1. I was trying to do the valve clearances on my SR500 today. The engine has a bad tapping in the top end (consistent with the revs) and I hope the cause is, as I found out today, that the inlet vlave has a clearance of 0.15mm (at least) as opposed to the 0.10mm that it should have. However when I went to turn the locknut (anti-clockwise, as in toward the front of the bike) on the tappet, the nut simply would not budge. Is it normal for these to be very tight? - should I persist and place greater pressure? I could have applied more, but obviously this is one bolt in particular which I don't want to round, and one complex of metal I don't want to hurt, and as a first-timer I was anxious of any such possibilities! Some previous owner seemed to have a penchant for absolutely over-tightening every sing nut and bolt (singles do shake things apart!) which might explain things. Any advice - can it take decent pressure, and is there another method (if it were external to the engine, I'd give it a bit of WD40)? Also, is it fine to take the rocker covers off when the bike is running? (-I want to verfiy my sense that the tapping is mainly coming from the inlet valve tappet)

  2. They tend to get pretty damn tight, I think it's the heat cycles and vibration taht does it.
    Use a SIX POINT socket or spanner to loosen the nut, a six pointer is much less likely to damage the edges of the nut.
    Be sure to hold the socket/spanner square on the nut, and crack away!
    Very worst that will happen is you'll be up for a second hand rocker arm, but that's very unlikely. If you damage the nut too badly, you can cut it off with a grinder and some patience.

    Regards, Andrew.
  3. try supporting the rocker arm while you un tighten it ie; get a freind to support it with a screw driver or something so all the force is not resting on the valve spring pin?
  4. Also, Idea, crack out the lpg torch, make sure no rubber components are in the vicinity, blast for a good 20 secinds (use your judgement), use a hex/six point socket to loosen (not 12, like conventional, think impact socket), post your thanks and adorations.
  5. As noted above, a six point socket held firmly over the nut (don't let it ride up and slip off) should sort it.

    Once you've got it moving, it should be OK. It's unlikely that any nut inside the constantly oily cam box will be suffering from corrosion :p so it should just be tight.

    Running for a few minutes with the valve cover off won't hurt the engine but it's likely to be very messy. It might be easier to do the adjustment and put the cover back before testing.