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Effects of exhaust leak

Discussion in 'Technical and Troubleshooting Torque' started by mattb, Dec 10, 2008.

  1. Hi All.

    Google's not helping today - can anybody list the general effects of an exhaust leak, in my case (in both my cases) the SR500 and GR650 are leaking at the join between the header and muffler. I know backfiring is one effect, because of the fresh air getting sucked in, and yesterday the GR was backfiring terribly and not starting. It also fouled its plugs, as does the SR regularly (though GR = oil* and / or petrol fouled, SR = carbon). Just exploring what contribution this leak might be making to other issues on the bikes...


    (*I know the reason for this - a twice-removed previous owner who perchance is an SR500 Club member, rebuilt the engine, said it's fine inside, except he bodged the valve seals).

  2. Burnt exhaust valve seat?
  3. Unless the leak's really huge, I wouldn't expect much effect. From my experience in the corrosive UK, where the default state of the average high mileage Jap four was to have big holes in the exhaust collector ('cos it was too awkward to weld old bean cans in to plug 'em up), a particularly sensitive bike might develop a bit of a midrange flat spot (which might, or might not, be curable by fiddling with the carb needle position), but I don't remember anyone's engine suffering anything too terminal.

    Lotsa Brit bikes have unclamped, push in pipe connections at the head which always leak and seem quite happy about it.

    A little bit of a blow round a slip joint isn't even in the same league. The downpipes on the Ural have unclamped joints to the balance pipe where leakage has blued the (rather poor) chrome in the area. It just seems to be factory spec.

    Leaks aren't really recommended practice and you should try to minimise them where you can, but on soft-tune bikes like yours, I'd not regard them as apocalyptic unless they're extreme.

    Mind you, if you've aftermarket mufflers or air filters and haven't upjetted to suit, anything likely to lean things out even further should probably receive some attention.