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fix ZX2R gearbox, worth it?

Discussion in 'Technical and Troubleshooting Torque' started by EVOSTi, May 10, 2006.

  1. ive come across a 1990 ZX2R ninja for sale, its said to be in good condition other than 'problem with second gear', price is $2000. this seems FAIRLY reasonable to me provided the bike is otherwise good.

    so im asking how hard is this to fix for a motorbike newbie? im a mechanic but have no experience working on bikes, im guesing its not as simple as separating the gearbox from the engine and replacing with a second hand one? is this a job a regualar mechanic can tackle, and even if i can, would it be cost effective?

    thanks in advance!
  2. I think you can just replace the second gear cog if that is all that damaged can't you??? My mate has a niggle with 2nd gear on his 00' R6 and he was informed that you can fix it by just having the second gear cog replaced (it is missing some teeth so occasionally skips with hard acceleration).

    Other you could just replace the gear box with a second hand one! Don't they just bolt on and off to the bottom of the engine???
  3. If you can get a hold of a service manual for the bike then it should be within your capabilities to fix. If it is jumping out of gear there are a couple of possible causes. Worn/bent selector forks or the dogs on the gear are worn. If its not too badly worn you may be able to get a machine shop to undercut the drive face of the dog. May wear through the case or induction hardening though (problem will then recurr). Best just to replace gear if you are going to be keeping it. Whatever it is its an engine out & split the cases job. Gearbox is integral with the engine in most bikes. Except for those weird Harley & BMW ones :LOL: :LOL:
  4. thanks for the replies guys. i will ring the dealership tomoz. yes dealership, which worries me a little cause i would think they would fix it themselves if it wasnt a huge problem. but yeah might be lucky and it could be just a syhcro or whatever. but yeah ill ring them, get more info then if it still sounds good i might go check it out on saturday.
  5. evosti,

    hi good luck on the bargain man but aren't bike gearboxes constant mesh meaning all gears turn all the time therefore no synchros. as you say though looks a little fishy if the dealer themselves wont fix it so just be careful dont wanna get burnt
  6. car gearboxes are constant mesh also, but they still have synchros.
    but yeah, if its still available ill have to bring a mate with me who has experience with bikes, just so i dont go ga-ga cause it looks good and hand over ll my money :)
  7. Offer the dealer some xtra cash to fix the problem, if they wont, ask wtf is up... If they don't have time ask if you can take it to another mechanic - better to throw away a small amount of cash and find out the truth than lay out the purchase price and find out later you're up shit creek.

    Of course make sure you find out what it will cost for someone else to chedk it out before commiting to anything...
  8. bike gearboxes are not constant mesh. they are dog boxes and don't have syncho's.

    the worst case is you will have to replace both gears and the gear selector drum. It may be wise to replace some bearings whilst you are there.

    It will probably be an engine out of from jobby, so if yo want to save money you will need to do a lot of labour yourself. Don't expect to just drop the bike off and pick it up and have a bargain.
  9. ibast - bike boxes ARE constant mesh.

    The term refers to whether the gears themselves move into and out of mesh by sliding along their shafts. The synchromesh on a car box matches speeds of input shaft and output gear DOG TEETH. Synchromesh boxes usually have many more teeth with sharp edges on them the reduce baulking (dogs not going into their matching holes).

    non-constant mesh gears are normally the reverse idler in a standard car box, or first and sometimes second in older non-synchro boxes like rovers and jaguars.

    PS; for the OP if you've not yet bought the bike, ride it and see - if bad, don't even bother buying as you will spend a packet fixing it when you would prefer to be out riding.

    If it is yours, try to find a second hand engine/gearbox from a wreckers and drop the lot in.
  10. well i rung the dealer up today. the bike in question has 65k's on it and rego till november. apparently the bike goes great, second gear works but is noisy.

    do people think this is a good buy (without having seen it obviously)? ill prob have a look at it saturday if i can.
    i spoke to a customer today at work who says on these bikes you cannot remove the geartrain from the engine to replace a damamged gear. apparently i would need to partially dissasemble the engine including removing head etc. sound about right?

    im keen to get my firt bike, and dont mind doing some work as long as it doesnt mean real dramas. and the guy i spoke to also reiterated that a bike shop is there to make money, and they wouldnt not repair it if it meant they could make more money from it which scares me into thinking it needs major money thrown at it.
  11. Mate sounds like a bit of a drama, if it was me, I'd look elsewhere... Thats my opinion, there is nothing more heart-breaking than buying something (especially that expensive), and finding out you need to spend another $200 here and another $350 there :mad:, and so-on, to make it work as it should... Move on...
    My thoughts anyway...
    Good Luck
  12. walk away dude
    there's plenty of good bikes out there

    no point ruining your first bike experience with a pos
  13. thanks guys always good to get another perspective. shame the bike looks so damn nice makes it hard to walk away :)
  14. You should still check it out, to see what they mean by noisy...My gearbox was noisy on my zxr and my mates zxr is as well.
    But I spose if there even bothering to mention it, Id reckon its fuked.
    Apparently most 90's models kawasaki models are noisy tho.
  16. I'm with you bonox.

    The dog ring is what gets moved by the shift fork. The manishaft gear runs on a bearing and isn't "connected" to the shaft as such. The dog ring is splined to the mainshaft, the dog ring engaging the mainshaft gear effectively connects gear and shaft.

    Generally (coz I know someone will come up with an obscure exception) in both car and bike boxes the lay and main gears are constantly engaged with each other.

    A 'synchro' is just a cone shaped device which rubs against the hub just before it meets the gear to help bring the hub up to speed with the gear and help them mesh. Not used in bikes or racing cars, the dogs on the dog ring just fall into place between the dogs on the main gear.

    Is it worth fixing the ZX2 box, dunno you'll have to crunch the numbers but it can be done.

    "Man made it, man can fix it"
  17. well i probably got nothing better to do tomoz, so maybe i should check it out? only prob is i dont have my license yet so cant acutally test ride it. but atleast it will be a place to start, havent even looked at 250's to buy yet. :(
  18. Dont do it yeah while u have to dissasemble the motor then oh well this needs fixing oh gaskets for this so just look for somethin else :grin:

  19. EVOSTi go have a look, but I wouldn't buy it without giving it a run and putting it through it's paces, there has been a few people mention that that model has a noisy gear box, but without riding it, you can't tell whether it is just the "noisy gear-box" of that model or something much worse, if your not sure, don't buy it until you can test-ride it, or as I said in a previous post, let it go, there are lots of nice bikes out there in the range/style you're looking at...
    Good luck.