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Timing problems

Discussion in 'Technical and Troubleshooting Torque' at netrider.net.au started by dhgarske, Sep 22, 2010.

  1. Guys
    I have a 97 SRV250 Renaissa see here http://www.flickr.com/photos/24659979@N07/sets/72157623777105805/
    i replaced broken valves... set the timing up, double checked, triple checked timing
    set on the right timing mark on flywheel, and valve cog... then 300degree turn anticlockwise to other timing mark, set up timing chain... done - engine spins freely when turned

    and still the exhaust on the rear cylinder is sucking instead of blowing

    ffffffffaaaaaaaaaaaaaaaarrrrrrrrrkkkkkkkkk!!!!!!!!!! (can i say that?)

    can someone just tell me what i need to do?

  2. Not sure about the model so this may be a ridiculous question but is it possible that you set it up at top dead centre of the wrong stroke? Or is the timing mark such that this is not possible?
  3. Make sure you haven't got the inlet and exhaust cams swapped. Sounds daft, but I once had to physically restrain a mate (a competent and experienced mechanic) from taking a sledgehammer to his bike for exactly that reason :D.
  4. double checked the mark on the flywheel - and took out the spark plug and put in a wire to make sure the piston was at the top... then double checked the timing chain cam sprocket...
  5. hmmmm... the timing chain drives the cog at the top that drives one cam that has both the inlet and exhaust on same ....
    but now you have me thinking......
  6. this is the baby

    the engine on the SRV250 is basically the same as the 250 Virago... a little different heads, twin carbs, and tuned up a bit...
  7. Ah, yeah :oops:. I've just worked out what an SRV is, so scratch my suggestion.

    Although, I suppose, you still have a situation where you have two of everything that look superficially similar but may not be identical. I'd expect the cams to be the same but stuff like the sprockets may not. I'm not familiar with the internals of the baby V, but is it possible that you've used the front cylinder timing marks for the rear and vice versa?

    Oddly enough, the same mate who swapped the cams in his Z1100 was a bit of a local expert on doing the timing on Yam TR1s, which, of course, have the parent of the big Virago lump. Used to reckon the procedure was very badly explained in the workshop manual.