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Rebuilding engine - dramas starting it. UPDATE RUNNING!!!

Discussion in 'Technical and Troubleshooting Torque' started by L0Ki, Nov 30, 2008.

  1. Ok Im in an annoying situation. Its a GPX250 engine.

    A couple of months ago pulled an engine apart. Left it apart and have come back to it lately. Got it back together and am trying to start it.

    It has spark, is getting fuel and has compression. And it doesnt start.

    I had stuffed up on the timing the first time, but thats fixed now as i copied it off my other GPX.

    Now im asking you people, the smarter ones what im doing wrong here. Ive drained the battery about 5 times now. Its getting rather annoying.

    I know theres the possibility of me getting the timing wrong but it cant be now. I even double checked with the manual.

    I dont have the radiator or any cooling system parts connected. Is this a problem. I just want to see if it starts. Dont worry i have oil in it though :p

    So is there anything in particular i have to have connected fo rit to run that im not aware of?

    Any help or ideas would be greatly appreciated at my time of frustration.


  2. I know you said you had the timing right but is it possible you timed it 180 degrees out and it's sparking on the wrong stroke?
  3. +1

    thats what i would be looking at
  4. Thanks guys but i think thats how i had it before i re-did the timing.

    But ill do the whole stick something into the spark plug whole and see if it anywhere near the right timing.

    Also a question about having no tank on atm. Do i have to cover the vacuum hose up or leave it alone?
  5. Whats the go with the alternator cover having two top dead centre marks that are exactly yhte same. How am i supposed to distiniguish between the compression stroke and the exhaust release stroke or watever. Atleast cylinder one has 1|T and 1|F whereas the the 2nd cylinder only has 2|T for both. WTF. Manual isnt any help either. Just says put the 2nd cylinder at TDC.
  6. I think that you need to learn about "Valve Events" and Camshaft timing, before you attemp this sort of thing again.

    Goodonya for having a go, though.
  7. simple check. take spark plug out and stick a pencil in the hole. turn by hand and watch the valves as you do so.

    as the piston rises on the exhaust stroke the exhaust valve will open at some point. past tdc on the same stroke the intake valve will open. there may be some overlap. Spark plug should NOT fire at this time. as you go past bdc and the piston begins to rise agin for the compression stroke valves remain shut and somewhere near tdc spark should fire.

    if this doesn't happen you've got the timing 180 deg rees out
  8. Lol i know how an engine works. I was just getting frustrated.

    Realised i had installed the cams in reverse because there the same profile its just where the sproket attaches that determines there difference.

    I got the bike spluttering now and running off the starter motor but my battery died before i could keep it going. Its on the charge now.

    And yes i do realise how stupid my question above was now that i think about. I was just desperate for an answer. Which i have now.
  9. We have lift off... started up and sounded great. Had no mufflers on it :twisted:

    Anyways thanks for your time! :)
  10. So was there a problem or was it just being obstinate?
  12. Oops sorry.

    Somehow I missed that entire post.
  13. I hope that you learned something here.
  14. :LOL:
    Well Done.
    Laughing WITH you, not AT you :wink:
    Glad to see you got her running