So got my new exhaust and went to put on but the bolts coming out of rear cylinder have stripped at end and pretty sure nut is knackered too, any ideas how to fix or how to get out where I can get some new bolts and nuts that will be suitable from 

Not sure which bolts you mean, but try release oil, heat and a bit of tapping. If they are knackered they will have to be drilled out and replaced. Should be able to buy bolts from any hardware store.

Been there done that, grab the shouldered part of the bolt ( biggest mole grips you can find), not the thread, turn the stud out and fit new ones, spray it with plus gas or some such penetrating oil and be patient, they will be tight but replacing them is better than trying to cut a new thread in there. They are a special bolt, head studs, you will need to get them from you local Yammie dealer should only cost about £4 each. Remember it's steel into aluminium so the stud is much harder than the head.

or weld on a nut and turn it with that,. the heat will penetrate the whole stud and make it easier to undo.

 

i always dab a bit of copper slip on the new stud to prevent galvanisation of the two metals

If I get it out in one piece and hacksaw the end 1/4 inch thats stripped will it have enough to hold the exhaust onto the cylinder. Or do I have to replace it

Replace them, there cheap as chips, .  get the right size.

I use stainless off ebay, just measure and check thread size

10 hours ago, drewpy said:

I use stainless off ebay, just measure and check thread size

Cheers ive had a look, and can't seem o find any that look the same , do I need that non threaded shoulder in the middle or could I just use a completely threaded stud 

You can make your own, threaded from end to end but it's better to use the right thing, go to your dealer or phone them get the right thing, the problem with cutting the end off is will it still fit and it's a half arsed job, do it right and do it once.

34 minutes ago, slice said:

do it right and do it once.

Don't know how much time I have wasted by not following the above advice!

3 hours ago, Spike101uk said:

Cheers ive had a look, and can't seem o find any that look the same , do I need that non threaded shoulder in the middle or could I just use a completely threaded stud 

not really difficult

http://www.ebay.co.uk/itm/Scooter-Moped-M6-x-M6-Exhaust-Studs-and-Nuts-/271650165199?hash=item3f3f9c91cf:g:zrYAAOSwuTxWAWF9

 

just check length and width. even if they are too long, leave them or cut them.

for that price just take a punt

Just one other thing, as Drewpy said, if your going to replace them then use a Copper slip or something similar when you reassemble it, it will make it so much easier for you or the next owner to get the bike apart, it won't melt at less than a thousand degrees. I bought one of these for about £6 and most every bolt I take off has a dollop when I tighten it.

Copperslip is great. Just remember your torque figures go up when you use it. Around 5 to 10%. Depends on the bolt size.