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RVF400 sudden change in exhaust note

Discussion in 'Technical and Troubleshooting Torque' started by nicka9x, Sep 3, 2011.

  1. Riding today suddenly the exhaust note changed with a very slight loss of power. When I reached home could hear exhaust noise coming from piston 3 side of engine. Feeling the temperature of each downpipe, all were extremely hot except the one from piston 3. I am thinking I have crack the exhaust manifold or exhaust gasket blown because the engine was still running reasonably smooth with a slight loss of power, if no spark I presume the power loss would be more noticeable.

  2. check for oil in the engine? Otherwise probably toasted exhaust gasket, or a screw coming loose, possibly a product of a toasted exhaust gasket.
  3. Have you checked for spark yet?
  4. +1

    Never presume anything, it will bite you and checking spark is pretty easy and then you can eliminate it.

    Even with a cracked manifold or a blown gasket I'd expect there would still be some heat in the pipe.

    If you have a blown gasket or cracked manifold try running the engine at night in the dark and you may see it.
  5. Today I checked and there was spark there. To check I removed lead and insert spark plug and placed it about 20 mm from chassis. Also had bike running and then disconnected spark plug lead from suspect piston and notice change in engine. Where downpipe connects to manifold could feel exhaust gases leaking out against my hand. Yes the downpipe on piston 3 does get warm but not as the same as the other 3 which are very hot.
  6. So you had a strong blue spark?

    A single cool down pipe and a sudden loss in power usually indicates a partially stuck float needle. Does it clear up at higher RPM?

    Your exhaust leak and sudden loss of power is worrying. Exhaust leaks can burn out exhaust valves. I hope the leak is just coincidental and the needle is the problem.

    Do a compression check.
  7. Finally had time to look into the problem and was amazed at what i found. When taking off the rear pipes I notice there was no gasket for cylinder 3. Put everything together with gaskets and is now good as gold.. IMG_4882.
  8. This pic of rear pipes showing black exhaust marks around pipe connecting to cylinder 3. IMG_4879.
  9. Good to know you've found the problem and gotten back to updating the thread :). Will keep this in mind if my VFR decides to do the same haha :).