The famous second gear problem

[coops]

Well I did a bit of searching on the subject and as a lot of us know they slip out of second gear cos the dog is worn. But I found a few threads where riders have symptoms of clutch slip or engine miss in second gear or some weird shit happening in second gear.
Well I had the same weird shit happening in second gear and Ive finally been advised its second gear spinning on the shaft. Its just pressed on the shaft, not splined or keyed in any way, just pressed on and relies on the interference fit to stop it spinning on the shaft.
Bloody ridiculous engineering if you ask me. So gotta strip engine completely to press a new gear on to a new shaft. No guarantees it wont happen again.
Very disappointed Yamaha.
So whats the fix for sure? I have a couple of ideas, but I need to actually see the dang thing before I comment here.
Is this very common problem? How can it be fixed for certain?
Not happy with the fizzer right now

[Stig]

you could get a keyway machined into the shaft and fit a wudruff key

[coops]

you could get a keyway machined into the shaft and fit a wudruff key

I was thinking the same stig. Wouldn't want too shear one in half though as they aren't very big. Would probably need to be as wide as possible. maybe 5mm.
I have a great engineer/machinist who will help out with that.
Would locktite retaining glue help? I doubt there would be any left on shaft once its pushed on there.
Does anyone know exactly how much the interference fit is supposed to be or the sizes of the shaft/hole journal?
Cheers.

[Stig]

IMHO the keyway would only have to be small as the interference fit takes most of the strain. The key is just a failsafe.....

[coops]

IMHO the keyway would only have to be small as the interference fit takes most of the strain. The key is just a failsafe.....

Your probably right stig thinks for your opinion. My mechanic/machinist will sort that problem out for me cheers.
Nearly got engine out today but couldn't get the sprocket off Will have to wait till I get rattle gun from work on it.

[DonTZ125]

With the engine still in and the chain still on, put a wood hammer through the spokes. This stops the sprocket and shaft from turning, so a socket and bar can get the nut off.

Make sure you've dealt with the lock washer ...

[coops]

With the engine still in and the chain still on, put a wood hammer through the spokes. This stops the sprocket and shaft from turning, so a socket and bar can get the nut off.

Make sure you've dealt with the lock washer ...

Basically did that except had mate on the foot brake. Used a long strong bar but I couldn't budge it.
Have rattle guns at work, can wait till Monday. Cheers Don

[coops]

Well ive got it all to bits and there aint much I can do about the pinion spinning on the shaft except get a new shaft and pinion and press on with correct Loctite.
Seems I have the other usual problem with second gear. Shift fork is bent and the dogs are worn quite bad. Probably not far from jumping out of gear. So im having them all background, blued. New shift fork and pinion.(5th wheel)
The dogs that are worn (driving second) have worn not centrally, they have worn more closer to the outside edge of the dog and hole. This could be the problem with these bikes. They arnt matched very well causing the gear (5th wheel) to walk out and this bends the fork. Just a theory.

I consider myself quite lucky really.....Imagine if it started jumping out of second gear BEFORE the pinion started spinning! I could've been doing the job twice.
Bugger that.

Last problem. Anyone got a YZF 750 clutch basket for me?

[reelrazor]

This could be the problem with these bikes. They arnt matched very well causing the gear (5th wheel) to walk out and this bends the fork. Just a theory.

Nah, the problem with these bikes (and all of them..from HD to Yam/Kaw/Suz/Hon/Duc/Tri....) is that people poorly time hard upshifts from 1-2 and when they miss, they bang the selector.

[coops]

This could be the problem with these bikes. They arnt matched very well causing the gear (5th wheel) to walk out and this bends the fork. Just a theory.

Nah, the problem with these bikes (and all of them..from HD to Yam/Kaw/Suz/Hon/Duc/Tri....) is that people poorly time hard upshifts from 1-2 and when they miss, they bang the selector.

Well you could be right, but there is definitely a problem with the dogs on my machine not being matched very well. Specifically with second gear. All other gears contact is central on the dog. but contact on second is nearer the outside of the dog. Which has nothing to do with bad shifting or bent fork.