Front gear is damaging drive shaft

[TeamSky1975]

I'm in need of some advice from experienced GS riders... I recently wanted to replace front & rear gear, together with the chain. But when I wanted to remove the front gear, I noticed how "loose" is was on the drive shaft. When I took it off, I could clearly see that the gear damaged all the tooth on the shaft 
The shaft is badly damaged... Is this a common problem? And what are my options now...?

Thank you experts!

[iamhiding]

I titled a post "clever front sprocket fix" or something like that the other day, worth a look.

[chornbe]

 
http://gstwins.com/gsboard/index.php?topic=70814.msg850917#msg850917

[chornbe]

FWIW, applying enough welding heat in situ to properly secure that bolt is probably not a great idea.

[iamhiding]

FWIW, applying enough welding heat in situ to properly secure that bolt is probably not a great idea.

yup thats my post. 

you're not wrong there, chains/sprockets probably develop a fair bit of heat themselves with high rpm metal on metal, couple that with engine heat but its nothing in comparison to the heat welding creates. don't really foresee it being a problem, ive seen sprockets/nuts welded into place when theres been no other option and its run faultless     now thats proper cringeworthy, theres no way i'd ever do that myself though.

the problem is that its ones of those 'little to no option' situations where you can either get creative or... you pull the whole motor down and replace the countershaft. ideally what id like to do is drill the centre of the shaft out a bit and tap it so i could put a bolt in. thats how my gsxr11 is, just a safety thing in case the sprocket nut comes lose. see what happens with it anyway really interested to see if anyones come up with their own solutions for this.

[peteGS]

If the splines or the shaft are that messed up, you can work on the gearbox without dismantling the whole engine.

You do need to remove it from the bike, but flip the motor upside down and the cases can be split without interfering with the top end. This means no need to worry about disturbing the base and head gasket, getting cylinders honed, etc.

Obviously you'll need to drain the oil first...