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YZF1000R Thunder ace, slipping in second..??

Discussion in 'Technical and Troubleshooting Torque' started by disassembled, Apr 21, 2008.

  1. Ok, so my mate has offered me his 1996 YZF1000R for $2500, which i think is a steal. It's mechanically pretty good, but has some fairing damage. I've ridden it, and it's super smooth, and feels pretty good.

    Anyway, the only issue with it, is that he says that it "slips" in second gear under hard acceleration. Now my first though was that the clutch was slipping under torque, but he's had this checked and supposedly that is not a problem.

    Just wondering if anyone had any opinions on this and what it might be.

  2. When you say it "slips", is it a shudder or jump, or is it a smooth slipping feel? Smooth slipping is clutch, that's relatively easy and cheap
    to fix. Shudder/jump/clunk is gearbox trouble, and that's big $$$.
  3. Just skip 2nd its a thou, so it will not be that big of a difference unless your really going for it.

    Ohhh and the 2nd gear problems are very common to yzf, fzr etc. I dont know why but thats my experience.
  4. I have not experienced said problem as i haven't opened it rght up so i can't say from personal experience, however i'm told it's a smooth slipping. I did ask if there was a crunch or shudder and he says no.

    This is a very good friend of mine, so he isn't going to bullshit me either.

    Worst case, what would it cost to rebuild gearbox?
  5. Clutch repair? Clutch kit ~150-200, a few seals and gaskets, labour time. Probably $400 including oil change. Or you could do it yourself at home
    if you are mechanically able and have good tools.

    Gearbox rebuild? Take the engine out, take the top end off, split the bottom end in two, replace what is busted, replace seals, check and replace bearings, rebuild engine, reinstall. $1500-3500.
  6. Sure it's not wheelspin? :grin:

    Seriously, a mate with a GS550 (of all things) put a mega cheap and ancient tyre on the back and then started complaining about clutch slip, particularly in the wet. It was only when I followed him one soggy day and actually observed what was happening that we realised that the tyre was letting go.

    Mind you, it says something about the forgiving handling of the GS that it didn't simply spit him off on the first wet roundabout :shock: .
  7. Yep, can't confirm this isn't the case. The rear tyre is in very good condition, and doesn't look particularly old. Bridgestone BT020 on the rear.
  8. It may be the clutch plates are not showing wear but two other things could be wrong.

    1. It may have had friction modified oils through it, so the plates my be impregnated with slippery compounds.

    2, the springs may be cactus. Often people doing bike clutches cut corners and only replace the clutch plates and not the spring.

    So, make sure the lever is adjusted properly and if it's a hydraulic clutch make sure the slave cylinder is retracting. Dump the oil and give it a good flush with diesel fuel. Replace the clutch plates. If it still slips, replace the springs also. Put good oil in it.
  9. You mean like dump the oil, replace it with diesel, run it for a few minutes, then drain it again. Fit a new oil filter and then fill with a good quality motorcycle oil? Worth a shot.
  10. If it was the clutch, it would be slipping in other gears too. I don't like the sound of it, I'd be thinking gearbox and steering clear.
  11. Possibly, but not always. Second may be loading things up just right for a small slippage. I've seen it in a car where it would only do it in a certain gear. A few days later it was doing it everywhere.

    But yeah, I'm not guaranteeing my approach will work. Only if you are confident it's not popping out of gear.

    Yeah MRX, give that a go.
  12. Hi Loz,

    You're right that the clutch should be slipping in other gears, however
    Wouldn't there be some other obvious sign if it was a gearbox problem though, eg: noisy box, missing gear, jittery power delivery, etc?

    Just a thought.
  13. The typical thing with Yamaha gearboxes, I'm told, is that they start dropping out of second if they've copped a bit of a flogging.

    I'd test ride the thing and give it the full bananas in second - do a few freeway onramps or whatever - so you can be satisfied you at least understand what's happening.
  14. For 2.5K I think I could live with a four speeder. As long as I wasn't drag racing :grin: .

    Seriously though, even if it's tired, it's still a lot of bike for the money.
  15. 55k on the clock, should be a reasonably healthy engine. Had some fairing damage on one side which has been repaired, starts first kick after sitting a while, new tyres, aftermarket pipe. I think it's pretty good overall.

    Wonder if it uses the same gearbox as the early R1's? or the late fzr1000's
  16. Yep, same engine as an FZR thou. Different crank though. Gearbox is the same as the FZR. Basicly a "Thunderace" is an FZR 1000 engine in a YZF 750 frame. The R1 is different everywhere.

    When your mate says "slips in 2nd gear" could he mean it slips out of second gear into neautral or perhaps third gear.

    I once had a YZF do a brief, rapid, scary and very harsh down and up shift by itself, exiting a bend, after I made a "lazy" upshift. It was as much my fault as the gear selector/box. I did not give the lever enough upstroke with my toe... I was a bit rushed.
    I was using a shipload of throttle and revs at the time and at around 140kmh + or -. The experiance was really horrible and left me needing a change of Kimbies, I made sure it never happened again.

    Anyway, as the clutch plates wear out, it will slip in 5th gear first. Then as the plates wear more you get slippage in the lower gears. HOWEVER! a YZF1000 being a YZF1000 (it's rider) is a lot more likely to get well into its torque curve in 2nd gear than any other. What I mean is, if you are into the meaty part of the torque curve with a substantial amount of throttle dialed in, on this machine, in higher gears, you are doing, go to jail speed... It's possible your friend is giving it the berries, mostly in 2nd, so he cites 2nd gear when he describes the problem. For example; it is unlikely that a law abiding citizen (on an FZR/YZF1000) would be bimbling along at 8000 RPM in 5th and then suddenly nail the throttle just to see if the clutch is going to slip.....Same applies to first gear, but the deterant is not so much a legal matter, but one of wanting ones arms to remain in their sockets. Although.... he may be tempted to do these things if he reads this post.

    You should not believe, or attempt to do, or be influenced by anything I write, as I have no understanding of motorcycles, mechanics, engineering, physics or human nature. This will be confirmed by some "moderators" of this site.
  17. Just had another read of the thread and noticed that it's done 55k Kms.

    You should find out if it's had its valve clearances done... they need it every 45k. This is critical. And there is 20 of the buggers... shims.
  18. If it is only limited to 2nd, it ain't ya clutch mate!!!!
    It will slip in any gear under harsh acceleration - does it?????

    Sounds like stuffed/worn dogs on the 2nd gear, you need real positive action to shift up through the gears, with slightly worn dogs the bike will disengage gear under load as the dogs have not fully engaged (radiused edges from poor shifting).

    You can be either firm and positive with your changes and live with it, or strip it down and replace 2nd gear, or put a YZF750R gearbox internals in it and make it a 6 speed!!!

  19. under full power applications throughout 1st, 2nd, 3rd, 4th, & 5th gears, clutch slip will manifest itself only in top gear until the clutch becomes more worn, then it will start to manifest itself in order down through the gearbox.

    Look at it this way.... Would a clutch be most likely to slip if you launched the bike in 1st or 5th gear if the clutch was a bit worn.......................

    If everything you say your friend said is true the clutch is worn out.

    I think "Ozzie" has failed to realize "human factors", and that is, your friend probably applies more power when he is in second gear, so he cites second gear when he explains the slippage. You say; " i'm told it's a smooth slipping. I did ask if there was a crunch or shudder and he says no. This is a very good friend of mine, so he isn't going to bullshit me either. "

    The symptom of what Ozzie cited is anything but "smooth slipping". My advice is; if you trust your mate buy the bike, fix the clutch and you have a good value Yam.
  20. Having said that, as Ibast posted, incorrect oil will make wet clutches slip too. So quiz your friend about the oil before replacing the drive & friction plates. Measure the clutch springs too, to make sure they are within spec.