[gizgrey]

hi all,i just picked up a very tidy 2005 125 pro for my lad, bike is very clean and well maintained only prob is it crunches badly into higher end gears,i know my 280 crunches slightly in higher gears but not a severe as this,i could here him and i was ahead of him with helmet on and still could here loudly...

there is no clutch drag goes into gear fine pulls away fine,was really hoping that this could turn out to be clutch plates....and if so are they relativly easy to replace ans set up..any info much appretiated..

all my fault of course for not checking the bike properly,but got at a very good price considering the condition overall..i changed gearoil last night for atf dex 3 but no diffrence..

another quick question the bike is a 125 pro 'racing' seamingly a slightly more beefed up version,is this right enough does say 125 special on origonal sale document,but never heard of it myself and if it is what is the diffrence from a normal pro

thanks again alan

This post has been edited by gizgrey: 21 July 2010 - 07:39 AM

[gizgrey]

anyone...

[JSE]

gizgrey, on Jul 23 2010, 12:31 PM, said:

anyone...

Did you see any nasty stuff on the magnet when you changed the oil? It might give an indication of a problem.

It's not the gears that "crunch" (this is a "constant mesh" gearbox and the gears are always engaged) but a series of pins
(sometimes called "dogs" for some reason) that slide into slotted collars and this is what transmits power to the gear sets.

Shifting under load can sometimes round off the ends of the pins and that will bounce a couple of times before sliding into
the slots and this sounds like gears crunching. Trials gearboxes are not designed to shift under load, but to stay in gear, so
the pin/collar design is different from, say, a roadracer.

A possibility.

Jon

[gizgrey]

JSE, on Jul 23 2010, 07:41 PM, said:

Did you see any nasty stuff on the magnet when you changed the oil? It might give an indication of a problem.

It's not the gears that "crunch" (this is a "constant mesh" gearbox and the gears are always engaged) but a series of pins
(sometimes called "dogs" for some reason) that slide into slotted collars and this is what transmits power to the gear sets.

Shifting under load can sometimes round off the ends of the pins and that will bounce a couple of times before sliding into
the slots and this sounds like gears crunching. Trials gearboxes are not designed to shift under load, but to stay in gear, so
the pin/collar design is different from, say, a roadracer.

A possibility.

Jon

hmmm sounds abit serious is this job something that could be done in my own shed,or is it a specialist job,i am pretty handy around the bike and am keen to get wired in,but wouldnt want to get stuck into something thats going to require a major stripdown and rebuild..or would it be better putting up with problem until it gets worse..!