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ZXR250 issues

Discussion in 'Technical and Troubleshooting Torque' started by Christmas, Feb 16, 2016.

  1. Hi guys,

    Long time stalker first time poster.

    I have been having trouble with this bike since I bought it, here goes. When i bought my 1999 balius about a week after i bought it one of my cylinders exploded and the piston and con rod exited the cylinder via my leg. About a week later i put a zxr250c engine into it which from my research was the same engine. Since putting that engine in i rejetted it as a zxr250c (125s across all 4) which caused it to bog down so i jetted it back to a zr250 (98s across all 4) considering i didnt change the airbox with the engine i thought ill change the air filter to a brand new one and voila problems solved. I went for a hour long ride after that which then caused the bike to overheat and spew coolant out the overflow so i filled it up and the bike was fine. Rode all the way home again without issues.

    A couple of days after that I went for a 5 minute ride and the bike temp light came on and the bike started to sound like a lawn mower so i pulled over for two minutes and turned the bike off to cool down. I started it up and no noise, soon as i gave it throttle though the bike made the lawn mower noise again. I gave it a fair bit put the revs around 15k and it went away and i was able to ride home. I did some research and concluded the overflow of the coolant was due to exhaust gases, so i changed the head gasket torqued everything to spec and the came chain back on in the right timing but since then its had this clicking noise while running and when i accelerate it makes a deep farting noise (for lack of a better word) and is lacking in power, so today i changed the exhaustngaskets thinking there might be a leak and still the ticking is there albeit quieter and the farting sound and a pack of power is still there is still there..

    Im at my wits end any ideas would be appreciated.

    In summary
    Overheated and sounds like lawn mower
    Changed head gasket
    Started making ticking noise and deep rumbling and loss of power
    Changed exhaust gaskets

    Also I have checked cam chain and tensioner as well, tensioner is working fine and cam chain looks fine

    Need help.

    Cheers, Jordan.
  2. Welcome Christmas,

    I wish I had an answer for you but it is beyond my spannering skills. Overheating seems to have triggered the issue so perhaps look at the cooling system, In terms of the noise, exhaust gasket perhaps?
  3. Double check the cam timing...maybe a tooth out ?
    • Agree Agree x 1
    • Informative Informative x 1
  4. Thanks for the replies, I agree, I think overheating triggered it but I'll be buggered with what happened. I've checked and rechecked exhaust gaskets and they're fine and seated correctly. As for cam chain, I checked that out today and it looks perfectly timed, correct links between marks at tdc

    Thinking possibly the head should be machined down on both upper and lower sides where the gasket goes in case it's warped.

    I also stripped down another time today I'm waiting for a second head gasket so I can put it together again. I did notice an incosistency in the water jacket around cylinder #2, they're all perfectly smooth on the outside of the cylinders except here, it seems to have a small dent in it, and because I can't see in at the right angle I have no way of knowing if it's nothing or it's a crack.

    I do have the cylinders off the old engine but they have rusted a little while theyre sitting.. Would they have to be re-machined to be used?
  5. Any water in the oil?

    Probably not it will be surface rust so a Rust cleaner and then a light sanding should be enough. Check the piston rings for consistency, perhaps consider replacing them.
  6. No, no water in the oil..

    Well thats good, I might clean them right up today and see then if it'll work.