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need some info quick

Discussion in 'Technical and Troubleshooting Torque' started by Tack, May 12, 2005.

  1. I need to know on a 1991 GPX250, if you can put it into second gear when the engine isn't running?


    Edit: Actually need to know if you can select all the gears when the engine isn't running...that is....select first then second then third etc running uo and down through the gears without to much problem??
  2. Sorry for this but the kids keep watching "The increadibles" continually

    [Frozone wife's voice]
    Why do you need to know?
    [\Frozone wife's voice]
  3. you may need to rock it back and forward a bit. Should change with a dead engine
  4. bwaahaa @ Ashes......yeah good question but why?
  5. I know that in general most bikes will change gears with some rocking but just need to be sure that a GPX will. Its real important that I know specifically that a GPX250 will change gears without the engine running...thats it does not rely on centrifical force to displace three small balls to allow a shift into 2nd gear for example.

    I have had to strip the engine and replace a bearing on the output shaft that disintegrated (literally). I have replaced the bearing and as part of my reassembly procedure I decided to check that the gearbox will run through the gears (just to make sure that everything works so I don't have to pull it apart again).

    Bottom line is: it selects 1st gear then it won't select second ( tried everything to get it into 2nd...spinning the shaft...rocking it)....I then found that moving the bearing slightly allowed the fork pin to move about 1mm in the selector drum groove which then allowed selection of 2nd gear(because the dog for 1st gear has three small balls to restrict its travel which then stops the fork from moving in its guide which stops the selector drum from rotating...). However after moving the bearing slightly I could select second and third...but not 4th....if you then moved the shaft slightly back the opposite way yo its original position it would then select 4th 5th and 6th gears.

    I looked at forks to see if they were bent....which they are not.... so I was stumped...i can't see a reason for the thing not to change into second gear except for the selector drum not being able to rotate due to the restriction of the three little balls in the dog drive...Thats why I decided to just ask a simple question to see if everyone else with a GPX250 can change gear ...just to double check!!

    It appears if the shaft is in the original position that the only gear I can't select is 2nd gear so I thought there might be something distinct to this bike that doesn't allow a change to second without it running or moving or something weird like that.
  6. oooh, that sounds like a right pickle :shock:

    umm, yeah, i was always able to select at least second on malissas GPX, pretty sure the rest of the gears were sweet too. cant remember if i had to roll the bike at all to get it to change, but thats a pretty common thing to have to do when shifting to neutral while the bike is off and stationary. have you got the manual there?
  7. Hi coconuts...thanks for your input....yeah I have the manual....I have read through this section however its not giving me any ideas as to why the thing won't change into 2nd.....I have checked all the measurements that the book offers and everything s well within tolerance.
  8. well, my next suggestion was going to be for you to go download the manual :? its possible that this is normal, maybe the bearings move more when its all oiled up and the whole bike is on the move? have you tried pulling in the clutch and seeing if that helps out?

    i am but a simpleton with this, wouldn't touch a gearbox with a 10 foot pole, i dont even know if i want to touch the carbs on the new ZXR :shock: i know it goes totally against everything male and manly, but maybe give a bike shop a ring tomorrow? most mechanics worth the grease in their fingernails should be able to tell you what the go is in the blink of an eye....
  9. I already have the assembly in the car ready to go for tomorrow morning....I just wanted to check that there wasn't a real simple reason for it not going in.....best to double check so the guy at the counter doesn't laugh and say: "its gotta be running cause the oil pressure pushes the little balls out and allows the gear dog to move and therefore allows the shift drum to rotate.....thats $50 thanks."


    "yeah the GPX is the only bike on the market that has artifical intelligence which prevents 2nd gear from engaging unless it knows you really do need to be in 2nd gear."
  10. I'd be rapt if I had a dog with three balls.
  11. I'd call him Jingles.
  12. The GPX will change into all gears while the ignition is off.
  13. I'd call him ET :)
  14. dont you mean "you would be rapt if you were a dog and had 3 balls" :LOL:
  15. I need to rock mine to get it down into first sometimes and the "positive netrual finder" might be why you are having difficulty
  16. The GPX is mechanically identical to the ZZR I believe? If that's the case, it'll have the positive neutral finder thingy, which means when the bike is stationary then the gears above neutral are locked out, making it easy to select neutral at the lights etc. The bike would have to be rolling to be able to select 2nd, 3rd etc.