How do I know if I need a new piston???

[McJamweasel]

Are there signs from the bike or do I just need to take it apart and have a butchers??

Basically, Im worried. The bikes got really vibey lately, it feels down on power(although that might just be me), it sounds fucking awful when Im starting it now(instead of just awful!) and theres a bit of a knock.

Is it new piston time?? Its getting on for about 30000km and I dont know whether its had a rebuld or not.
____________________
BCF: Be yourself, just don't be an arse.

[Ropehead]

the only way is 2 take the head off then u can check the bore for any signes of ware and dammage,
check the very top where the rings stop at the top of the stroke, see if it has worn a groove, if so you might need it re-honeing and some new rings,
But just start with the head dont go whipping it all off,
Let me know how it goes,

and drain the coolent first and get a new head gasket and maybe some nuts 2 if they arn't looking 2 good.

[McJamweasel]

Cheers mate, will do that when I get a chance.
____________________
BCF: Be yourself, just don't be an arse.

[Kickstart]

Hi

The NSR uses a plated barrel which will barely wear, and which you cannot do much with if it does. The chances of it being worn are very slim, but if it is then you will probably have to get it replated (although there are 5 sizes of piston to match the exact size of the bore).

Loosing power and being a bit rattly does sound like the piston. If you need a hand then give me a shout

All the best

Keith