tacho flicking b/n 10-11,000rpm (zx7r)


For background info the engine has got 17,000kms on it, the carbies (not flatsides) are jetted (dynojet) and its fitted with a Yoshi can.
Any ideas engine gurus? Could it also need an ignition advancer?
thanx
Seanzx7r
ps it runs very sweet and powerful in the rest of the rev range