Will it effect performance of two wheeler engiene if it is kept idle for many days and how often shold I change oil if kept idle

Keeping Gas Cleaned, drained is more important than your oil, if you question the oil, replace it.

Change oil before using bike for season.

I run my bike once a week and have put gas saver in it to keep gas from clogging jets.

If laying bike up for more than month, would drain all gas.

Good luck

Chuck