when is it time for new reeds?

[Yamahauler]

my tri-z is breaking up in the top end RPM's, could it be the reeds or something else?

[Yamahauler]

....also, where can you buy new reeds. Does Boysen make them for the Tri-Z?

[Mr. Sandman]

Top end RPM sputtering could be a number of things, from jetting to a dirty air filter. As for determining when it's time for new reeds, you'll have to remove the reed cage and look at them. If they're slightly open when they should be closed, you can either replace them or if they're still in good condition, remove them and flip them over. If the reed ends are tattered or worn looking, replace them.
http://www.boyesen.com/