I've not heard of anyone having this problem before,
and would be surprised if the temperature is causing the problem.
COULD IT BE that you forgot to re-install the rubber bush
and the bolt has bottomed out in the threaded hole ?
Because it won't now move in OR out, instinct tells me
that you are going to have difficulty removing it

Your description of the bolt not turning in eiither direction
does sound very much like it may have been cross threaded,
even though you think not because it has gone so far in,
but it is only an M6 x 1.0 thread, so it's quite possible.
Worse case scenario if you can't get the bolt out, is that you will have to replace the bar. ( £94.79

)
The other bits that might also need replacing, depending on whether they are damaged now,
or get damaged trying to remove the bolt are :
PFKL120405 WEIGHT. H/BAR SP £ 20.95
PFKL1204075 BUSH, RUBBER, 27X10X21MM £ 10.59
PFKL1204055 FINISHER. HANDLE BAR £ 10.47
PFKL202981 SCREW,CSK,M6X1.0X60,SLV £ 0.72
PFKL1204060 SLEEVE.WEIGHT.H/BAR £ 7.58
( Part numbers and prices from
World of Triumph )
So before spening all that Cash it's worth trying to get the bolt out ....
First of all - do you know of any local engineering company that might be able to help ?
Or, you could try ( at your own risk of course ! ) .......
Heating it up to see if that will free it off ....
Try a hot air blower or hair dryer on it for a few minutes first, and unscrewing it while hot.
If that doesn't work, it might need even more heat - so consider
stripping anything away that might get melted such as grip covers and wiring,
and then try a blow torch - the aim being to try and expand the hole with heat
thus loosening the grip on the bolt, but bearing in mind that the rubber bush will probably MELT,
as may the powder coating finish of the hande bar,
plus the silver finisher / weight are likely to all become discoloured.
If it IS cross threaded, then using brute force may be the ony answer -
try using a vice grip ( Mole grips ) on the head of the bolt - if it's still acccessible to give more leverage.
You should be prepared for the head of the bolt shearing off if it's that tight,
and then you're into the realms of trying to drill it out and re-thread the hole,
or in the worse case scenario as above - having to buy a new handlebar + other parts !
Good luck - let us know how you get on !
