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Three cylinders gone? Your opinion please.

Discussion in 'Technical and Troubleshooting Torque' started by Ghibli, Jul 3, 2006.

  1. Hi guys
    i'd like your opinion on this.
    I bought a CBR250R last month, 55K on the clock.
    The bike sounded great, no smoke and plenty of guts.
    Last week I flooded the engine trying to start it, and I coul not getting to go. So I thought I take it for a major service, so that everything is taken care of.
    Well, the guy from the garage just called to tell me that there is no compression on 3 cylinders and the engine is toast.
    Is this possible? I rode the bike up to 120km/h with still plenty of throttle to go. Can the bike do that on one cylinder?
    Your opinion please.

  2. Something definitely not adding up there... :?
  3. Too hard to comment without actually seeing the bike.
    But to answer your question, no the bike wouldn't do 120 on one cylinder.
    You probably didn't flood the engine, it most likely had a major failure.
    Maybe it through a cam chain or similar. I'd certainly be asking more questions of your mechanic or getting a second opinion.
  4. well theres TOAST and theres toast i guess.

    Is there NO compression or 'less' compresion?

    if it was badly flooded you may have bent a valve or 2 (hmm, may be) which will result in 0 compression and the need for a head job at least (and not the good sort)
  5. It doesn't sound to me like your mech is telling you it is only running on one cyclinder - he's saying that compression is very low on three cylinders. Different thing. I doubt this is in any way related to flooding the engine (but I stand to be corrected).
    If you've got really low compression on more than one cylinder, there are several possibilities:
    - timing chain has jumped a tooth (unlikely but possible)
    - piston rings and/or bores are shagged (this is what he is probably trying to tell you. Whether it is true is another issue.) symptom is blue smoke under revs and load.
    - valve clearances are all closed up. Symptom is black smoke.
    - valve seats and/or guides are very worn, or even possibly bent the valves (but I can't quite see how). symtom is blue or black smoke, especially at startup or pulling away.
    - you've managed to hole three pistons (and deserve a special prize!) Lotsa smoke.
    I think I'd be getting someone else to do a diagnosis before spending any more money, just to be sure.

    edit: oh, and also head gasket failure, cracked head, cracked block... but lets not go there :wink:
  6. A complete engine rebuild on a bike with only 55k does sound a bit unlikely.

    I'd be getting a second opinion; even though it was not running when you took it in, the diagnosis and quote does seem to be just a little 'convenient'.....
  7. To go from 120kph to shagged by flooding it doesn't sound right.

    At 55k your bores arent going to be great, possibly a good flooding has washed the oil from the bores and so no compression. Sometimes happens with motors that sit for a long time, they won't start because the bores are dry and rings cant seal well enough to provide the compression needed to fire.

    If this is the case you should be able to pull the plugs, squirt some oil on the bores, spin over to spread oil on the bore, replace plugs and off you go. Well kinda smokey at first but better than one cyl. worth.
  8. Sounds like it's just time for a freshen up.

    It's a little 4-potter that revs it's guts out.

    Don't know if anyone here saw thee Peking to Paris on the ABC awhile ago, but my old man used to own the yellow De Dion. The car was restored in 1988 and was driven in regular rallies and did the 16 000km treck no worries without a rebuild. It olny does about 16-1800 rpm max.

    The harder something has to work, the quicker it will wear out.
  9. Unfortunately the same thing happened to me somewhat. Few days after i purchased my cbr250 it died on me.

    Lost compression in 1 cylinder. Problem was valves needed to be replaced. So they ordered in new valves and did some other stuff to it and now runs like a dream! Problem was it was $.

  10. Where abouts do you live?