Any gearbox experts?

Has to be the selector forks or detent return spring/lever.
It won't improve!

 

My bike is jumping out of 5th on a regular basis now. It's only when I
change up clutchless, which I've always done. Should I be taking the
thing apart and mending it or will it be ok if I just remember to always
use the clutch for 5th?

--

Paul.
CBR1100XX SuperBlackbird (Buen mueble de patio)
And a pushbike of some sort.
BOTAFOT #4
BOTAFOF #30
MRO #24
OMF #15
UKRMMA #30

Ovejas y buitres:
http://personales.ya.com/wibbleypants/

 

No. It's fucked.

 

But will it go bang?

--

Paul.
CBR1100XX SuperBlackbird (Buen mueble de patio)
And a pushbike of some sort.
BOTAFOT #4
BOTAFOF #30
MRO #24
OMF #15
UKRMMA #30

Ovejas y buitres:
http://personales.ya.com/wibbleypants/

 

Not usually, eventually it will just keep jumping.
You are damaging the dogs on the gear cluster most likely, if not already.

 

I remember Pip had this on his RF900, but in a lower gear and it jumped
back in.

Hog is dead right, it'll never mend its self. It'll just get worse over
time. How worse and how quickly depends on a lot of things.

 

The ZZR did this in second gear and got gradually worse over about
8000 miles, until it refused to stay in gear at all. The next (second
hand, natch) engine and box has been doing it for about the last 4000
miles.

ISTR a vertically-challenged "vince" of this parish had a similar
problem and his did 'go bang' on the Severn Bridge, but ICBW.

 

Si, Niguel muy rápidamente en el Ebay

 

Qué?

 

What I don't understand is how comes it jumps out under power. When I
were a lad and rebuilt lots of car gearboxes, I seem to remember that
the cogs held themselves interlocked under power and it would be
virtually impossible to jump out. Sure, when you let off the power,
that's when they would separate. Do bike gearboxes have straight cut
cogs or summat?

Must dig out the HBOL.

--

Paul.
CBR1100XX SuperBlackbird (Buen mueble de patio)
And a pushbike of some sort.
BOTAFOT #4
BOTAFOF #30
MRO #24
OMF #15
UKRMMA #30

Ovejas y buitres:
http://personales.ya.com/wibbleypants/

 

Silly sod.

--

Paul.
CBR1100XX SuperBlackbird (Buen mueble de patio)
And a pushbike of some sort.
BOTAFOT #4
BOTAFOF #30
MRO #24
OMF #15
UKRMMA #30

Ovejas y buitres:
http://personales.ya.com/wibbleypants/

 

¿Cómo?

--

Paul.
CBR1100XX SuperBlackbird (Buen mueble de patio)
And a pushbike of some sort.
BOTAFOT #4
BOTAFOF #30
MRO #24
OMF #15
UKRMMA #30

Ovejas y buitres:
http://personales.ya.com/wibbleypants/

 

They are quite simple things, yes.

 

Bike gearboxes are all dog boxes with exception of one or two I think.
This means that all ratios are already meshed together. It's only that
the gear pair you want to use are locked to the shafts by sliding dogs
that are themselves locked to the shafts. Car gearboxes are different,
having the cogs that slide, and syncro rings that make sure the cogs
don't clash teeth as they mesh.

When the dogs wear in a bike gearbox, they do so on the leading edge of
the driven dog, and the trailing edge of the driven dog. This can
produce a wear pattern [1] that can tend to push the driving dog back
off the driven dog. Hence the 'jumping out of gear'. The only pressure
usually needed to make sure the dogs don't disengage is the detent
spring. This, however wasn't designed as a substitute for knackered
dogs.

[1] and resultant force.

 

My guess is a locking spring or whatever which has weakened.

 

Do you know how a bike gearbox works? How many springs are there, and
why would it only affect 5th?