ZZR1400 jumping out of 3rd
Discussion
Hey all, new to these parts of the forum what with recently buying a Rage buggy with the above motor in the back. Looking for some advice from those experienced in bike gearboxes.
During a recent track day it started jumping out of third gear at any hint of torque, with an awful banging/shunting. Kinda felt like the dogs were jumping apart then straight away re-engaging. Needless to say I soon skipped though the box stepping past third, but otherwise all the other gears select and run fine, as does the engine.
I’ve pulled the custom belly pan off and found a chipped tooth on 3rd gear, about half the width of the tooth taking about a quarter off it’s height.
Question is, is this likely to be the potential cause or a symptom of the fault?
Otherwise the dogs look in a used but not worn out condition with a tiny radius on the corners. It’s an engine out job anyway, just be nice to know what I might be looking at to got it sorted.
Thanks in advance!
During a recent track day it started jumping out of third gear at any hint of torque, with an awful banging/shunting. Kinda felt like the dogs were jumping apart then straight away re-engaging. Needless to say I soon skipped though the box stepping past third, but otherwise all the other gears select and run fine, as does the engine.
I’ve pulled the custom belly pan off and found a chipped tooth on 3rd gear, about half the width of the tooth taking about a quarter off it’s height.
Question is, is this likely to be the potential cause or a symptom of the fault?
Otherwise the dogs look in a used but not worn out condition with a tiny radius on the corners. It’s an engine out job anyway, just be nice to know what I might be looking at to got it sorted.
Thanks in advance!
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The gear wheels themselves are permanently engaged, the shifting is done with the dog clutches sliding sideways, visible in between some of the gears.
I’d imagine you have a dog gear jumping out and re-engaging, and the shock has chipped the gear tooth. Could be something like a bent selector fork, or a worn dog clutch.
Your chip is on one of the teeth you can see clearly?
I’d imagine you have a dog gear jumping out and re-engaging, and the shock has chipped the gear tooth. Could be something like a bent selector fork, or a worn dog clutch.
Your chip is on one of the teeth you can see clearly?
King Herald said:
It should hopefully be as simple as fitting a new gear, and double check your selector fork for bends or wear. Plus the shifter drum for wear too, just to make sure the dog clutch is being thrust fully into place.
I had a Fireblade box jumping out of gear - 2nd IIRC. I planned just to replace the single gear, but the price of a complete 'box' (2 x shafts, selector drum, forks etc) off breaker was way cheaper than a single new gear. And breakers wouldn't (to me at least) sell single gears. So I assembled a new gearset with the 'best' bits of both boxes. so unless you particularly want to buy new, I'd be looking at a new set of box internals off a breaker. Dunno of the kawasaki is like the Honda, but on it once the motor was upside down removing the bottom of the cases to get to the gears didn't disturb the mains.
A quick dirty thing to check before anything else is that the spring on the selector detent pin (or equivalent) isn't weak or sticking. A friend spent months babying a bike as it had that behaviour in 2nd until he discovered the box was actually fine. I've no idea why it only impacted one gear, but it can happen.
Cheers all, here’s a pic of the offending gear.
The engine runs a Flatshifter Expert system and I was making good use of it on track so wouldn’t be surprised if I’ve bent something, especially because it’s gone from being all OK with no previous issues to banging away like a trooper.
And yes I’d seen that whole gearboxes are available from breakers for sensible money compared to the price of a new parts. Looks like gearbox access for this engine is a full split the crankcase job.
The engine runs a Flatshifter Expert system and I was making good use of it on track so wouldn’t be surprised if I’ve bent something, especially because it’s gone from being all OK with no previous issues to banging away like a trooper.
And yes I’d seen that whole gearboxes are available from breakers for sensible money compared to the price of a new parts. Looks like gearbox access for this engine is a full split the crankcase job.
Krikkit said:
I wouldn't really want to fit another box unless you can identify the failure really... It might just happen again!
When/who set up the flatshifter? Is it possible that it's not set up quite right, allowing the engine torque to start rising before full gear engagement?
Yea, but OP says it's in a Rage buggy and not a bike. BIke engines in cars work great (I had one!) but there's far more weight than a bike to haul around, it won't pop wheelies or spin-up the wheels to take up transmission shocks; I doubt there's even the equivalent of a cush drive. Bike boxes get a proper hammering in cars. Even cars with manual shifts will wear the dogs/chip gears in time.When/who set up the flatshifter? Is it possible that it's not set up quite right, allowing the engine torque to start rising before full gear engagement?
You doubting Thomas tvrolet, there is indeed cush built into the drive transfer box courtesy of those nice people at Quaife 
And Krikkit, I bought the machine with everything installed as commissioned by the previous owners. Given their background experience and everything lavished on it I’m sure everything would have been set up right at the outset.
It had been used pretty hard on track previously mind, so that combined with a bit of new driver ham fistedness on my part what with it being my first bike engined car and track session, wouldn’t surprise me if I’ve busted it.
Live and learn and all that... Fix it up, sniff out the root cause, train the driver up and hopefully it won’t happen again in the too near future
And Krikkit, I bought the machine with everything installed as commissioned by the previous owners. Given their background experience and everything lavished on it I’m sure everything would have been set up right at the outset.
It had been used pretty hard on track previously mind, so that combined with a bit of new driver ham fistedness on my part what with it being my first bike engined car and track session, wouldn’t surprise me if I’ve busted it.
Live and learn and all that... Fix it up, sniff out the root cause, train the driver up and hopefully it won’t happen again in the too near future
There is also cush in the clutch basket on most bikes.
Ive been a motorcycle tech for 20 years now and of all boxes, kawas are most likely to fail. (more commonly 2nd)
Best get used to repairing it,as when in a car, you've doubled the weight so effectively doubled the torque load on it.
Ive been a motorcycle tech for 20 years now and of all boxes, kawas are most likely to fail. (more commonly 2nd)
Best get used to repairing it,as when in a car, you've doubled the weight so effectively doubled the torque load on it.
Krikkit said:
I wouldn't really want to fit another box unless you can identify the failure really... It might just happen again!
When/who set up the flatshifter? Is it possible that it's not set up quite right, allowing the engine torque to start rising before full gear engagement?
Do they use an ignition interrupter for the gear shift, like the old Tiptronics used to, or is there something more sinister? When/who set up the flatshifter? Is it possible that it's not set up quite right, allowing the engine torque to start rising before full gear engagement?
I have heard of gearboxes being ‘undercut’ to make them stay in gear better under high power. No idea what it means though, unless it is putting a taper/ridge on the dog clutch teeth so it pulls in rather that pops out?
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